mirror of
https://codeberg.org/ziglang/zig.git
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f50c647977
Implements deflate compression from scratch. A history window is kept in the writer's buffer for matching and a chained hash table is used to find matches. Tokens are accumulated until a threshold is reached and then outputted as a block. Flush is used to indicate end of stream. Additionally, two other deflate writers are provided: * `Raw` writes only in store blocks (the uncompressed bytes). It utilizes data vectors to efficiently send block headers and data. * `Huffman` only performs Huffman compression on data and no matching. The above are also able to take advantage of writer semantics since they do not need to keep a history. Literal and distance code parameters in `token` have also been reworked. Their parameters are now derived mathematically, however the more expensive ones are still obtained through a lookup table (expect on ReleaseSmall). Decompression bit reading has been greatly simplified, taking advantage of the ability to peek on the underlying reader. Additionally, a few bugs with limit handling have been fixed.
2550 lines
96 KiB
Zig
2550 lines
96 KiB
Zig
//! Allocates statically ~224K (128K lookup, 96K tokens).
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//!
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//! The source of an `error.WriteFailed` is always the backing writer. After an
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//! `error.WriteFailed`, the `.writer` becomes `.failing` and is unrecoverable.
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//! After a `flush`, the writer also becomes `.failing` since the stream has
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//! been finished. This behavior also applies to `Raw` and `Huffman`.
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// Implementation details:
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// A chained hash table is used to find matches. `drain` always preserves `flate.history_len`
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// bytes to use as a history and avoids tokenizing the final bytes since they can be part of
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// a longer match with unwritten bytes (unless it is a `flush`). The minimum match searched
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// for is of length `seq_bytes`. If a match is made, a longer match is also checked for at
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// the next byte (lazy matching) if the last match does not meet the `Options.lazy` threshold.
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//
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// Up to `block_token` tokens are accumalated in `buffered_tokens` and are outputted in
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// `write_block` which determines the optimal block type and frequencies.
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const builtin = @import("builtin");
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const std = @import("std");
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const mem = std.mem;
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const math = std.math;
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const assert = std.debug.assert;
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const Io = std.Io;
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const Writer = Io.Writer;
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const Compress = @This();
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const token = @import("token.zig");
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const flate = @import("../flate.zig");
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/// Until #104 is implemented, a ?u15 takes 4 bytes, which is unacceptable
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/// as it doubles the size of this already massive structure.
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///
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/// Also, there are no `to` / `from` methods because LLVM 21 does not
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/// optimize away the conversion from and to `?u15`.
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const PackedOptionalU15 = packed struct(u16) {
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value: u15,
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is_null: bool,
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pub fn int(p: PackedOptionalU15) u16 {
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return @bitCast(p);
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}
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pub const null_bit: PackedOptionalU15 = .{ .value = 0, .is_null = true };
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};
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/// After `flush` is called, all vtable calls with result in `error.WriteFailed.`
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writer: Writer,
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has_history: bool,
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bit_writer: BitWriter,
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buffered_tokens: struct {
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/// List of `TokenBufferEntryHeader`s and their trailing data.
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list: [@as(usize, block_tokens) * 3]u8,
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pos: u32,
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n: u16,
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lit_freqs: [286]u16,
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dist_freqs: [30]u16,
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pub const empty: @This() = .{
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.list = undefined,
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.pos = 0,
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.n = 0,
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.lit_freqs = @splat(0),
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.dist_freqs = @splat(0),
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};
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},
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lookup: struct {
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/// Indexes are the hashes of four-bytes sequences.
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///
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/// Values are the positions in `chain` of the previous four bytes with the same hash.
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head: [1 << lookup_hash_bits]PackedOptionalU15,
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/// Values are the non-zero number of bytes backwards in the history with the same hash.
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///
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/// The relationship of chain indexes and bytes relative to the latest history byte is
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/// `chain_pos -% chain_index = history_index`.
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chain: [32768]PackedOptionalU15,
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/// The index in `chain` which is of the newest byte of the history.
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chain_pos: u15,
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},
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container: flate.Container,
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hasher: flate.Container.Hasher,
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opts: Options,
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const BitWriter = struct {
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output: *Writer,
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buffered: u7,
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buffered_n: u3,
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pub fn init(w: *Writer) BitWriter {
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return .{
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.output = w,
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.buffered = 0,
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.buffered_n = 0,
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};
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}
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/// Asserts `bits` is zero-extended
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pub fn write(b: *BitWriter, bits: u56, n: u6) Writer.Error!void {
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assert(@as(u8, b.buffered) >> b.buffered_n == 0);
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assert(@as(u57, bits) >> n == 0); // n may be 56 so u57 is needed
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const combined = @shlExact(@as(u64, bits), b.buffered_n) | b.buffered;
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const combined_bits = @as(u6, b.buffered_n) + n;
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const out = try b.output.writableSliceGreedy(8);
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mem.writeInt(u64, out[0..8], combined, .little);
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b.output.advance(combined_bits / 8);
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b.buffered_n = @truncate(combined_bits);
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b.buffered = @intCast(combined >> (combined_bits - b.buffered_n));
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}
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/// Assserts one byte can be written to `b.otuput` without rebasing.
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pub fn byteAlign(b: *BitWriter) void {
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b.output.unusedCapacitySlice()[0] = b.buffered;
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b.output.advance(@intFromBool(b.buffered_n != 0));
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b.buffered = 0;
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b.buffered_n = 0;
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}
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pub fn writeClen(
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b: *BitWriter,
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hclen: u4,
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clen_values: []u8,
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clen_extra: []u8,
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clen_codes: [19]u16,
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clen_bits: [19]u4,
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) Writer.Error!void {
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// Write the first four clen entries seperately since they are always present,
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// and writing them all at once takes too many bits.
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try b.write(clen_bits[token.codegen_order[0]] |
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@shlExact(@as(u6, clen_bits[token.codegen_order[1]]), 3) |
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@shlExact(@as(u9, clen_bits[token.codegen_order[2]]), 6) |
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@shlExact(@as(u12, clen_bits[token.codegen_order[3]]), 9), 12);
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var i = hclen;
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var clen_bits_table: u45 = 0;
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while (i != 0) {
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i -= 1;
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clen_bits_table <<= 3;
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clen_bits_table |= clen_bits[token.codegen_order[4..][i]];
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}
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try b.write(clen_bits_table, @as(u6, hclen) * 3);
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for (clen_values, clen_extra) |value, extra| {
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try b.write(
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clen_codes[value] | @shlExact(@as(u16, extra), clen_bits[value]),
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clen_bits[value] + @as(u3, switch (value) {
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0...15 => 0,
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16 => 2,
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17 => 3,
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18 => 7,
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else => unreachable,
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}),
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);
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}
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}
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};
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/// Number of tokens to accumulate before outputing as a block.
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/// The maximum value is `math.maxInt(u16) - 1` since one token is reserved for end-of-block.
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const block_tokens: u16 = 1 << 15;
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const lookup_hash_bits = 15;
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const Hash = u16; // `u[lookup_hash_bits]` is not used due to worse optimization (with LLVM 21)
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const seq_bytes = 3; // not intended to be changed
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const Seq = std.meta.Int(.unsigned, seq_bytes * 8);
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const TokenBufferEntryHeader = packed struct(u16) {
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kind: enum(u1) {
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/// Followed by non-zero `data` byte literals.
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bytes,
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/// Followed by the length as a byte
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match,
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},
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data: u15,
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};
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const BlockHeader = packed struct(u3) {
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final: bool,
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kind: enum(u2) { stored, fixed, dynamic, _ },
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pub fn int(h: BlockHeader) u3 {
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return @bitCast(h);
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}
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pub const Dynamic = packed struct(u17) {
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regular: BlockHeader,
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hlit: u5,
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hdist: u5,
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hclen: u4,
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pub fn int(h: Dynamic) u17 {
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return @bitCast(h);
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}
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};
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};
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fn outputMatch(c: *Compress, dist: u15, len: u8) Writer.Error!void {
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// This must come first. Instead of ensuring a full block is never left buffered,
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// draining it is defered to allow end of stream to be indicated.
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if (c.buffered_tokens.n == block_tokens) {
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@branchHint(.unlikely); // LLVM 21 optimizes this branch as the more likely without
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try c.writeBlock(false);
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}
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const header: TokenBufferEntryHeader = .{ .kind = .match, .data = dist };
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c.buffered_tokens.list[c.buffered_tokens.pos..][0..2].* = @bitCast(header);
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c.buffered_tokens.list[c.buffered_tokens.pos + 2] = len;
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c.buffered_tokens.pos += 3;
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c.buffered_tokens.n += 1;
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c.buffered_tokens.lit_freqs[@as(usize, 257) + token.LenCode.fromVal(len).toInt()] += 1;
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c.buffered_tokens.dist_freqs[token.DistCode.fromVal(dist).toInt()] += 1;
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}
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fn outputBytes(c: *Compress, bytes: []const u8) Writer.Error!void {
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var remaining = bytes;
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while (remaining.len != 0) {
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if (c.buffered_tokens.n == block_tokens) {
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@branchHint(.unlikely); // LLVM 21 optimizes this branch as the more likely without
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try c.writeBlock(false);
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}
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const n = @min(remaining.len, block_tokens - c.buffered_tokens.n, math.maxInt(u15));
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assert(n != 0);
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const header: TokenBufferEntryHeader = .{ .kind = .bytes, .data = n };
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c.buffered_tokens.list[c.buffered_tokens.pos..][0..2].* = @bitCast(header);
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@memcpy(c.buffered_tokens.list[c.buffered_tokens.pos + 2 ..][0..n], remaining[0..n]);
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c.buffered_tokens.pos += @as(u32, 2) + n;
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c.buffered_tokens.n += n;
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for (remaining[0..n]) |b| {
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c.buffered_tokens.lit_freqs[b] += 1;
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}
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remaining = remaining[n..];
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}
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}
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fn hash(x: u32) Hash {
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return @intCast((x *% 0x9E3779B1) >> (32 - lookup_hash_bits));
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}
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/// Trades between speed and compression size.
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///
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/// Default paramaters are [taken from zlib]
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/// (https://github.com/madler/zlib/blob/v1.3.1/deflate.c#L112)
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pub const Options = struct {
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/// Perform less lookups when a match of at least this length has been found.
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good: u16,
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/// Stop when a match of at least this length has been found.
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nice: u16,
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/// Don't attempt a lazy match find when a match of at least this length has been found.
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lazy: u16,
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/// Check this many previous locations with the same hash for longer matches.
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chain: u16,
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// zig fmt: off
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pub const level_1: Options = .{ .good = 4, .nice = 8, .lazy = 0, .chain = 4 };
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pub const level_2: Options = .{ .good = 4, .nice = 16, .lazy = 0, .chain = 8 };
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pub const level_3: Options = .{ .good = 4, .nice = 32, .lazy = 0, .chain = 32 };
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pub const level_4: Options = .{ .good = 4, .nice = 16, .lazy = 4, .chain = 16 };
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pub const level_5: Options = .{ .good = 8, .nice = 32, .lazy = 16, .chain = 32 };
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pub const level_6: Options = .{ .good = 8, .nice = 128, .lazy = 16, .chain = 128 };
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pub const level_7: Options = .{ .good = 8, .nice = 128, .lazy = 32, .chain = 256 };
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pub const level_8: Options = .{ .good = 32, .nice = 258, .lazy = 128, .chain = 1024 };
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pub const level_9: Options = .{ .good = 32, .nice = 258, .lazy = 258, .chain = 4096 };
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// zig fmt: on
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pub const fastest = level_1;
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pub const default = level_6;
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pub const best = level_9;
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};
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/// It is asserted `buffer` is least `flate.max_history_len` bytes.
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/// It is asserted `output` has a capacity of at least 8 bytes.
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pub fn init(
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output: *Writer,
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buffer: []u8,
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container: flate.Container,
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opts: Options,
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) Writer.Error!Compress {
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assert(output.buffer.len > 8);
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assert(buffer.len >= flate.max_window_len);
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// note that disallowing some of these simplifies matching logic
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assert(opts.chain != 0); // use `Huffman`, disallowing this simplies matching
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assert(opts.good >= 3 and opts.nice >= 3); // a match will (usually) not be found
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assert(opts.good <= 258 and opts.nice <= 258); // a longer match will not be found
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assert(opts.lazy <= opts.nice); // a longer match will (usually) not be found
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if (opts.good <= opts.lazy) assert(opts.chain >= 1 << 2); // chain can be reduced to zero
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try output.writeAll(container.header());
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return .{
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.writer = .{
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.buffer = buffer,
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.vtable = &.{
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.drain = drain,
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.flush = flush,
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.rebase = rebase,
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},
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},
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.has_history = false,
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.bit_writer = .init(output),
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.buffered_tokens = .empty,
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.lookup = .{
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// init `value` is max so there is 0xff pattern
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.head = @splat(.{ .value = math.maxInt(u15), .is_null = true }),
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.chain = undefined,
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.chain_pos = math.maxInt(u15),
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},
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.container = container,
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.opts = opts,
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.hasher = .init(container),
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};
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}
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fn drain(w: *Writer, data: []const []const u8, splat: usize) Writer.Error!usize {
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errdefer w.* = .failing;
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// There may have not been enough space in the buffer and the write was sent directly here.
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// However, it is required that all data goes through the buffer to keep a history.
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//
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// Additionally, ensuring the buffer is always full ensures there is always a full history
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// after.
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const data_n = w.buffer.len - w.end;
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_ = w.fixedDrain(data, splat) catch {};
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assert(w.end == w.buffer.len);
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try rebaseInner(w, 0, 1, false);
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return data_n;
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}
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fn flush(w: *Writer) Writer.Error!void {
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defer w.* = .failing;
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const c: *Compress = @fieldParentPtr("writer", w);
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try rebaseInner(w, 0, w.buffer.len - flate.history_len, true);
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try c.bit_writer.output.rebase(0, 1);
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c.bit_writer.byteAlign();
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try c.hasher.writeFooter(c.bit_writer.output);
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}
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fn rebase(w: *Writer, preserve: usize, capacity: usize) Writer.Error!void {
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return rebaseInner(w, preserve, capacity, false);
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}
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pub const rebase_min_preserve = flate.history_len;
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pub const rebase_reserved_capacity = (token.max_length + 1) + seq_bytes;
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fn rebaseInner(w: *Writer, preserve: usize, capacity: usize, eos: bool) Writer.Error!void {
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if (!eos) {
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assert(@max(preserve, rebase_min_preserve) + (capacity + rebase_reserved_capacity) <= w.buffer.len);
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assert(w.end >= flate.history_len + rebase_reserved_capacity); // Above assert should
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// fail since rebase is only called when `capacity` is not present. This assertion is
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// important because a full history is required at the end.
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} else {
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assert(preserve == 0 and capacity == w.buffer.len - flate.history_len);
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}
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const c: *Compress = @fieldParentPtr("writer", w);
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const buffered = w.buffered();
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const start = @as(usize, flate.history_len) * @intFromBool(c.has_history);
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const lit_end: usize = if (!eos)
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buffered.len - rebase_reserved_capacity - (preserve -| flate.history_len)
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else
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buffered.len -| (seq_bytes - 1);
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var i = start;
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var last_unmatched = i;
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// Read from `w.buffer` instead of `buffered` since the latter may not
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// have enough bytes. If this is the case, this variable is not used.
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var seq: Seq = mem.readInt(
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std.meta.Int(.unsigned, (seq_bytes - 1) * 8),
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w.buffer[i..][0 .. seq_bytes - 1],
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.big,
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);
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if (buffered[i..].len < seq_bytes - 1) {
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@branchHint(.unlikely);
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assert(eos);
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seq = undefined;
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assert(i >= lit_end);
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}
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while (i < lit_end) {
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var match_start = i;
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seq <<= 8;
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seq |= buffered[i + (seq_bytes - 1)];
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var match = c.matchAndAddHash(i, hash(seq), token.min_length - 1, c.opts.chain, c.opts.good);
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i += 1;
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if (match.len < token.min_length) continue;
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var match_unadded = match.len - 1;
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lazy: {
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if (match.len >= c.opts.lazy) break :lazy;
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if (match.len >= c.writer.buffered()[i..].len) {
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@branchHint(.unlikely); // Only end of stream
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break :lazy;
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}
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var chain = c.opts.chain;
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var good = c.opts.good;
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if (match.len >= good) {
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chain >>= 2;
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good = math.maxInt(u8); // Reduce only once
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}
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seq <<= 8;
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seq |= buffered[i + (seq_bytes - 1)];
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const lazy = c.matchAndAddHash(i, hash(seq), match.len, chain, good);
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match_unadded -= 1;
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i += 1;
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if (lazy.len > match.len) {
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match_start += 1;
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match = lazy;
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match_unadded = match.len - 1;
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}
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}
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assert(i + match_unadded == match_start + match.len);
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assert(mem.eql(
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u8,
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buffered[match_start..][0..match.len],
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buffered[match_start - 1 - match.dist ..][0..match.len],
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)); // This assert also seems to help codegen.
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try c.outputBytes(buffered[last_unmatched..match_start]);
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try c.outputMatch(@intCast(match.dist), @intCast(match.len - 3));
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last_unmatched = match_start + match.len;
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if (last_unmatched + seq_bytes >= w.end) {
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@branchHint(.unlikely);
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assert(eos);
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i = undefined;
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break;
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}
|
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|
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while (true) {
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seq <<= 8;
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seq |= buffered[i + (seq_bytes - 1)];
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_ = c.addHash(i, hash(seq));
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i += 1;
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match_unadded -= 1;
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if (match_unadded == 0) break;
|
|
}
|
|
assert(i == match_start + match.len);
|
|
}
|
|
|
|
if (eos) {
|
|
i = undefined; // (from match hashing logic)
|
|
try c.outputBytes(buffered[last_unmatched..]);
|
|
c.hasher.update(buffered[start..]);
|
|
try c.writeBlock(true);
|
|
return;
|
|
}
|
|
|
|
try c.outputBytes(buffered[last_unmatched..i]);
|
|
c.hasher.update(buffered[start..i]);
|
|
|
|
const preserved = buffered[i - flate.history_len ..];
|
|
assert(preserved.len > @max(rebase_min_preserve, preserve));
|
|
@memmove(w.buffer[0..preserved.len], preserved);
|
|
w.end = preserved.len;
|
|
c.has_history = true;
|
|
}
|
|
|
|
fn addHash(c: *Compress, i: usize, h: Hash) void {
|
|
assert(h == hash(mem.readInt(Seq, c.writer.buffer[i..][0..seq_bytes], .big)));
|
|
|
|
const l = &c.lookup;
|
|
l.chain_pos +%= 1;
|
|
|
|
// Equivilent to the below, however LLVM 21 does not optimize `@subWithOverflow` well at all.
|
|
// const replaced_i, const no_replace = @subWithOverflow(i, flate.history_len);
|
|
// if (no_replace == 0) {
|
|
if (i >= flate.history_len) {
|
|
@branchHint(.likely);
|
|
const replaced_i = i - flate.history_len;
|
|
// The following is the same as the below except uses a 32-bit load to help optimizations
|
|
// const replaced_seq = mem.readInt(Seq, c.writer.buffer[replaced_i..][0..seq_bytes], .big);
|
|
comptime assert(@sizeOf(Seq) <= @sizeOf(u32));
|
|
const replaced_u32 = mem.readInt(u32, c.writer.buffered()[replaced_i..][0..4], .big);
|
|
const replaced_seq: Seq = @intCast(replaced_u32 >> (32 - @bitSizeOf(Seq)));
|
|
|
|
const replaced_h = hash(replaced_seq);
|
|
// The following is equivilent to the below since LLVM 21 doesn't optimize it well.
|
|
// l.head[replaced_h].is_null = l.head[replaced_h].is_null or
|
|
// l.head[replaced_h].int() == l.chain_pos;
|
|
const empty_head = l.head[replaced_h].int() == l.chain_pos;
|
|
const null_flag = PackedOptionalU15.int(.{ .is_null = empty_head, .value = 0 });
|
|
l.head[replaced_h] = @bitCast(l.head[replaced_h].int() | null_flag);
|
|
}
|
|
|
|
const prev_chain_index = l.head[h];
|
|
l.chain[l.chain_pos] = @bitCast((l.chain_pos -% prev_chain_index.value) |
|
|
(prev_chain_index.int() & PackedOptionalU15.null_bit.int())); // Preserves null
|
|
l.head[h] = .{ .value = l.chain_pos, .is_null = false };
|
|
}
|
|
|
|
/// If the match is shorter, the returned value can be any value `<= old`.
|
|
fn betterMatchLen(old: u16, prev: []const u8, bytes: []const u8) u16 {
|
|
assert(old < @min(bytes.len, token.max_length));
|
|
assert(prev.len >= bytes.len);
|
|
assert(bytes.len >= token.min_length);
|
|
|
|
var i: u16 = 0;
|
|
const Block = std.meta.Int(.unsigned, @min(math.divCeil(
|
|
comptime_int,
|
|
math.ceilPowerOfTwoAssert(usize, @bitSizeOf(usize)),
|
|
8,
|
|
) catch unreachable, 256) * 8);
|
|
|
|
if (bytes.len < token.max_length) {
|
|
@branchHint(.unlikely); // Only end of stream
|
|
|
|
while (bytes[i..].len >= @sizeOf(Block)) {
|
|
const a = mem.readInt(Block, prev[i..][0..@sizeOf(Block)], .little);
|
|
const b = mem.readInt(Block, bytes[i..][0..@sizeOf(Block)], .little);
|
|
const diff = a ^ b;
|
|
if (diff != 0) {
|
|
@branchHint(.likely);
|
|
i += @ctz(diff) / 8;
|
|
return i;
|
|
}
|
|
i += @sizeOf(Block);
|
|
}
|
|
|
|
while (i != bytes.len and prev[i] == bytes[i]) {
|
|
i += 1;
|
|
}
|
|
assert(i < token.max_length);
|
|
return i;
|
|
}
|
|
|
|
if (old >= @sizeOf(Block)) {
|
|
// Check that a longer end is present, otherwise the match is always worse
|
|
const a = mem.readInt(Block, prev[old + 1 - @sizeOf(Block) ..][0..@sizeOf(Block)], .little);
|
|
const b = mem.readInt(Block, bytes[old + 1 - @sizeOf(Block) ..][0..@sizeOf(Block)], .little);
|
|
if (a != b) return i;
|
|
}
|
|
|
|
while (true) {
|
|
const a = mem.readInt(Block, prev[i..][0..@sizeOf(Block)], .little);
|
|
const b = mem.readInt(Block, bytes[i..][0..@sizeOf(Block)], .little);
|
|
const diff = a ^ b;
|
|
if (diff != 0) {
|
|
i += @ctz(diff) / 8;
|
|
return i;
|
|
}
|
|
i += @sizeOf(Block);
|
|
if (i == 256) break;
|
|
}
|
|
|
|
const a = mem.readInt(u16, prev[i..][0..2], .little);
|
|
const b = mem.readInt(u16, bytes[i..][0..2], .little);
|
|
const diff = a ^ b;
|
|
i += @ctz(diff) / 8;
|
|
assert(i <= token.max_length);
|
|
return i;
|
|
}
|
|
|
|
test betterMatchLen {
|
|
try std.testing.fuzz({}, testFuzzedMatchLen, .{});
|
|
}
|
|
|
|
fn testFuzzedMatchLen(_: void, input: []const u8) !void {
|
|
@disableInstrumentation();
|
|
var r: Io.Reader = .fixed(input);
|
|
var buf: [1024]u8 = undefined;
|
|
var w: Writer = .fixed(&buf);
|
|
var old = r.takeLeb128(u9) catch 0;
|
|
var bytes_off = @max(1, r.takeLeb128(u10) catch 258);
|
|
const prev_back = @max(1, r.takeLeb128(u10) catch 258);
|
|
|
|
while (r.takeByte()) |byte| {
|
|
const op: packed struct(u8) {
|
|
kind: enum(u2) { splat, copy, insert_imm, insert },
|
|
imm: u6,
|
|
|
|
pub fn immOrByte(op_s: @This(), r_s: *Io.Reader) usize {
|
|
return if (op_s.imm == 0) op_s.imm else @as(usize, r_s.takeByte() catch 0) + 64;
|
|
}
|
|
} = @bitCast(byte);
|
|
(switch (op.kind) {
|
|
.splat => w.splatByteAll(r.takeByte() catch 0, op.immOrByte(&r)),
|
|
.copy => write: {
|
|
const start = w.buffered().len -| op.immOrByte(&r);
|
|
const len = @min(w.buffered().len - start, r.takeByte() catch 3);
|
|
break :write w.writeAll(w.buffered()[start..][0..len]);
|
|
},
|
|
.insert_imm => w.writeByte(op.imm),
|
|
.insert => w.writeAll(r.take(
|
|
@min(r.bufferedLen(), @as(usize, op.imm) + 1),
|
|
) catch unreachable),
|
|
}) catch break;
|
|
} else |_| {}
|
|
|
|
w.splatByteAll(0, (1 + 3) -| w.buffered().len) catch unreachable;
|
|
bytes_off = @min(bytes_off, @as(u10, @intCast(w.buffered().len - 3)));
|
|
const prev_off = bytes_off -| prev_back;
|
|
assert(prev_off < bytes_off);
|
|
const prev = w.buffered()[prev_off..];
|
|
const bytes = w.buffered()[bytes_off..];
|
|
old = @min(old, bytes.len - 1, token.max_length - 1);
|
|
|
|
const diff_index = mem.indexOfDiff(u8, prev, bytes).?; // unwrap since lengths are not same
|
|
const expected_len = @min(diff_index, 258);
|
|
errdefer std.debug.print(
|
|
\\prev : '{any}'
|
|
\\bytes: '{any}'
|
|
\\old : {}
|
|
\\expected: {?}
|
|
\\actual : {}
|
|
++ "\n", .{
|
|
prev, bytes, old,
|
|
if (old < expected_len) expected_len else null, betterMatchLen(old, prev, bytes),
|
|
});
|
|
if (old < expected_len) {
|
|
try std.testing.expectEqual(expected_len, betterMatchLen(old, prev, bytes));
|
|
} else {
|
|
try std.testing.expect(betterMatchLen(old, prev, bytes) <= old);
|
|
}
|
|
}
|
|
|
|
fn matchAndAddHash(c: *Compress, i: usize, h: Hash, gt: u16, max_chain: u16, good_: u16) struct {
|
|
dist: u16,
|
|
len: u16,
|
|
} {
|
|
const l = &c.lookup;
|
|
const buffered = c.writer.buffered();
|
|
|
|
var chain_limit = max_chain;
|
|
var best_dist: u16 = undefined;
|
|
var best_len = gt;
|
|
const nice = @min(c.opts.nice, buffered[i..].len);
|
|
var good = good_;
|
|
|
|
search: {
|
|
if (l.head[h].is_null) break :search;
|
|
// Actually a u15, but LLVM 21 does not optimize that as well (it truncates it each use).
|
|
var dist: u16 = l.chain_pos -% l.head[h].value;
|
|
while (true) {
|
|
chain_limit -= 1;
|
|
|
|
const match_len = betterMatchLen(best_len, buffered[i - 1 - dist ..], buffered[i..]);
|
|
if (match_len > best_len) {
|
|
best_dist = dist;
|
|
best_len = match_len;
|
|
if (best_len >= nice) break;
|
|
if (best_len >= good) {
|
|
chain_limit >>= 2;
|
|
good = math.maxInt(u8); // Reduce only once
|
|
}
|
|
}
|
|
|
|
if (chain_limit == 0) break;
|
|
const next_chain_index = l.chain_pos -% @as(u15, @intCast(dist));
|
|
// Equivilent to the below, however LLVM 21 optimizes the below worse.
|
|
// if (l.chain[next_chain_index].is_null) break;
|
|
// dist, const out_of_window = @addWithOverflow(dist, l.chain[next_chain_index].value);
|
|
// if (out_of_window == 1) break;
|
|
dist +%= l.chain[next_chain_index].int(); // wrapping for potential null bit
|
|
comptime assert(flate.history_len == PackedOptionalU15.int(.null_bit));
|
|
// Also, doing >= flate.history_len gives worse codegen with LLVM 21.
|
|
if ((dist | l.chain[next_chain_index].int()) & flate.history_len != 0) break;
|
|
}
|
|
}
|
|
|
|
c.addHash(i, h);
|
|
return .{ .dist = best_dist, .len = best_len };
|
|
}
|
|
|
|
fn clenHlen(freqs: [19]u16) u4 {
|
|
// Note that the first four codes (16, 17, 18, and 0) are always present.
|
|
if (builtin.mode != .ReleaseSmall and (std.simd.suggestVectorLength(u16) orelse 1) >= 8) {
|
|
const V = @Vector(16, u16);
|
|
const hlen_mul: V = comptime m: {
|
|
var hlen_mul: [16]u16 = undefined;
|
|
for (token.codegen_order[3..], 0..) |i, hlen| {
|
|
hlen_mul[i] = hlen;
|
|
}
|
|
break :m hlen_mul;
|
|
};
|
|
const encoded = freqs[0..16].* != @as(V, @splat(0));
|
|
return @intCast(@reduce(.Max, @intFromBool(encoded) * hlen_mul));
|
|
} else {
|
|
var max: u4 = 0;
|
|
for (token.codegen_order[4..], 1..) |i, len| {
|
|
max = if (freqs[i] == 0) max else @intCast(len);
|
|
}
|
|
return max;
|
|
}
|
|
}
|
|
|
|
test clenHlen {
|
|
var freqs: [19]u16 = @splat(0);
|
|
try std.testing.expectEqual(0, clenHlen(freqs));
|
|
for (token.codegen_order, 1..) |i, len| {
|
|
freqs[i] = 1;
|
|
try std.testing.expectEqual(len -| 4, clenHlen(freqs));
|
|
freqs[i] = 0;
|
|
}
|
|
}
|
|
|
|
/// Returns the number of values followed by the bitsize of the extra bits.
|
|
fn buildClen(
|
|
dyn_bits: []const u4,
|
|
out_values: []u8,
|
|
out_extra: []u8,
|
|
out_freqs: *[19]u16,
|
|
) struct { u16, u16 } {
|
|
assert(dyn_bits.len <= out_values.len);
|
|
assert(out_values.len == out_extra.len);
|
|
|
|
var len: u16 = 0;
|
|
var extra_bitsize: u16 = 0;
|
|
|
|
var remaining_bits = dyn_bits;
|
|
var prev: u4 = 0;
|
|
while (true) {
|
|
const b = remaining_bits[0];
|
|
const n_max = @min(@as(u8, if (b != 0)
|
|
if (b != prev) 1 else 6
|
|
else
|
|
138), remaining_bits.len);
|
|
prev = b;
|
|
|
|
var n: u8 = 0;
|
|
while (true) {
|
|
remaining_bits = remaining_bits[1..];
|
|
n += 1;
|
|
if (n == n_max or remaining_bits[0] != b) break;
|
|
}
|
|
const code, const extra, const xsize = switch (n) {
|
|
0 => unreachable,
|
|
1...2 => .{ b, 0, 0 },
|
|
3...10 => .{
|
|
@as(u8, 16) + @intFromBool(b == 0),
|
|
n - 3,
|
|
@as(u8, 2) + @intFromBool(b == 0),
|
|
},
|
|
11...138 => .{ 18, n - 11, 7 },
|
|
else => unreachable,
|
|
};
|
|
while (true) {
|
|
out_values[len] = code;
|
|
out_extra[len] = extra;
|
|
out_freqs[code] += 1;
|
|
extra_bitsize += xsize;
|
|
len += 1;
|
|
if (n != 2) {
|
|
@branchHint(.likely);
|
|
break;
|
|
}
|
|
// Code needs outputted once more
|
|
n = 1;
|
|
}
|
|
if (remaining_bits.len == 0) break;
|
|
}
|
|
|
|
return .{ len, extra_bitsize };
|
|
}
|
|
|
|
test buildClen {
|
|
//dyn_bits: []u4,
|
|
//out_values: *[288 + 30]u8,
|
|
//out_extra: *[288 + 30]u8,
|
|
//out_freqs: *[19]u16,
|
|
//struct { u16, u16 }
|
|
var out_values: [288 + 30]u8 = undefined;
|
|
var out_extra: [288 + 30]u8 = undefined;
|
|
var out_freqs: [19]u16 = @splat(0);
|
|
const len, const extra_bitsize = buildClen(&([_]u4{
|
|
1, // A
|
|
2, 2, // B
|
|
3, 3, 3, // C
|
|
4, 4, 4, 4, // D
|
|
5, // E
|
|
5, 5, 5, 5, 5, 5, //
|
|
5, 5, 5, 5, 5, 5,
|
|
5, 5,
|
|
0, 1, // F
|
|
0, 0, 1, // G
|
|
} ++ @as([138 + 10]u4, @splat(0)) // H
|
|
), &out_values, &out_extra, &out_freqs);
|
|
try std.testing.expectEqualSlices(u8, &.{
|
|
1, // A
|
|
2, 2, // B
|
|
3, 3, 3, // C
|
|
4, 16, // D
|
|
5, 16, 16, 5, 5, // E
|
|
0, 1, // F
|
|
0, 0, 1, // G
|
|
18, 17, // H
|
|
}, out_values[0..len]);
|
|
try std.testing.expectEqualSlices(u8, &.{
|
|
0, // A
|
|
0, 0, // B
|
|
0, 0, 0, // C
|
|
0, (0), // D
|
|
0, (3), (3), 0, 0, // E
|
|
0, 0, // F
|
|
0, 0, 0, // G
|
|
(127), (7), // H
|
|
}, out_extra[0..len]);
|
|
try std.testing.expectEqual(2 + 2 + 2 + 7 + 3, extra_bitsize);
|
|
try std.testing.expectEqualSlices(u16, &.{
|
|
3, 3, 2, 3, 1, 3, 0, 0,
|
|
0, 0, 0, 0, 0, 0, 0, 0,
|
|
3, 1, 1,
|
|
}, &out_freqs);
|
|
}
|
|
|
|
fn writeBlock(c: *Compress, eos: bool) Writer.Error!void {
|
|
const toks = &c.buffered_tokens;
|
|
if (!eos) assert(toks.n == block_tokens);
|
|
assert(toks.lit_freqs[256] == 0);
|
|
toks.lit_freqs[256] = 1;
|
|
|
|
var dyn_codes_buf: [286 + 30]u16 = undefined;
|
|
var dyn_bits_buf: [286 + 30]u4 = @splat(0);
|
|
|
|
const dyn_lit_codes_bitsize, const dyn_last_lit = huffman.build(
|
|
&toks.lit_freqs,
|
|
dyn_codes_buf[0..286],
|
|
dyn_bits_buf[0..286],
|
|
15,
|
|
true,
|
|
);
|
|
const dyn_lit_len = @max(257, dyn_last_lit + 1);
|
|
|
|
const dyn_dist_codes_bitsize, const dyn_last_dist = huffman.build(
|
|
&toks.dist_freqs,
|
|
dyn_codes_buf[dyn_lit_len..][0..30],
|
|
dyn_bits_buf[dyn_lit_len..][0..30],
|
|
15,
|
|
true,
|
|
);
|
|
const dyn_dist_len = @max(1, dyn_last_dist + 1);
|
|
|
|
var clen_values: [288 + 30]u8 = undefined;
|
|
var clen_extra: [288 + 30]u8 = undefined;
|
|
var clen_freqs: [19]u16 = @splat(0);
|
|
const clen_len, const clen_extra_bitsize = buildClen(
|
|
dyn_bits_buf[0 .. dyn_lit_len + dyn_dist_len],
|
|
&clen_values,
|
|
&clen_extra,
|
|
&clen_freqs,
|
|
);
|
|
|
|
var clen_codes: [19]u16 = undefined;
|
|
var clen_bits: [19]u4 = @splat(0);
|
|
const clen_codes_bitsize, _ = huffman.build(
|
|
&clen_freqs,
|
|
&clen_codes,
|
|
&clen_bits,
|
|
7,
|
|
false,
|
|
);
|
|
const hclen = clenHlen(clen_freqs);
|
|
|
|
const dynamic_bitsize = @as(u32, 14) +
|
|
(4 + @as(u6, hclen)) * 3 + clen_codes_bitsize + clen_extra_bitsize +
|
|
dyn_lit_codes_bitsize + dyn_dist_codes_bitsize;
|
|
const fixed_bitsize = n: {
|
|
const freq7 = 1; // eos
|
|
var freq8: u16 = 0;
|
|
var freq9: u16 = 0;
|
|
var freq12: u16 = 0; // 7 + 5 - match freqs always have corresponding 5-bit dist freq
|
|
var freq13: u16 = 0; // 8 + 5
|
|
for (toks.lit_freqs[0..144]) |f| freq8 += f;
|
|
for (toks.lit_freqs[144..256]) |f| freq9 += f;
|
|
assert(toks.lit_freqs[256] == 1);
|
|
for (toks.lit_freqs[257..280]) |f| freq12 += f;
|
|
for (toks.lit_freqs[280..286]) |f| freq13 += f;
|
|
break :n @as(u32, freq7) * 7 +
|
|
@as(u32, freq8) * 8 + @as(u32, freq9) * 9 +
|
|
@as(u32, freq12) * 12 + @as(u32, freq13) * 13;
|
|
};
|
|
|
|
stored: {
|
|
for (toks.dist_freqs) |n| if (n != 0) break :stored;
|
|
// No need to check len frequencies since they each have a corresponding dist frequency
|
|
assert(for (toks.lit_freqs[257..]) |f| (if (f != 0) break false) else true);
|
|
|
|
// No matches. If the stored size is smaller than the huffman-encoded version, it will be
|
|
// outputed in a store block. This is not done with matches since the original input would
|
|
// need to be stored since the window may slid, and it may also exceed 65535 bytes. This
|
|
// should be OK since most inputs with matches should be more compressable anyways.
|
|
const stored_align_bits = -%(c.bit_writer.buffered_n +% 3);
|
|
const stored_bitsize = stored_align_bits + @as(u32, 32) + @as(u32, toks.n) * 8;
|
|
if (@min(dynamic_bitsize, fixed_bitsize) < stored_bitsize) break :stored;
|
|
|
|
try c.bit_writer.write(BlockHeader.int(.{ .kind = .stored, .final = eos }), 3);
|
|
try c.bit_writer.output.rebase(0, 5);
|
|
c.bit_writer.byteAlign();
|
|
c.bit_writer.output.writeInt(u16, c.buffered_tokens.n, .little) catch unreachable;
|
|
c.bit_writer.output.writeInt(u16, ~c.buffered_tokens.n, .little) catch unreachable;
|
|
|
|
// Relatively small buffer since regular draining will
|
|
// always consume slightly less than 2 << 15 bytes.
|
|
var vec_buf: [4][]const u8 = undefined;
|
|
var vec_n: usize = 0;
|
|
var i: usize = 0;
|
|
|
|
assert(c.buffered_tokens.pos != 0);
|
|
while (i != c.buffered_tokens.pos) {
|
|
const h: TokenBufferEntryHeader = @bitCast(toks.list[i..][0..2].*);
|
|
assert(h.kind == .bytes);
|
|
|
|
i += 2;
|
|
vec_buf[vec_n] = toks.list[i..][0..h.data];
|
|
i += h.data;
|
|
|
|
vec_n += 1;
|
|
if (i == c.buffered_tokens.pos or vec_n == vec_buf.len) {
|
|
try c.bit_writer.output.writeVecAll(vec_buf[0..vec_n]);
|
|
vec_n = 0;
|
|
}
|
|
}
|
|
|
|
toks.* = .empty;
|
|
return;
|
|
}
|
|
|
|
const lit_codes, const lit_bits, const dist_codes, const dist_bits =
|
|
if (dynamic_bitsize < fixed_bitsize) codes: {
|
|
try c.bit_writer.write(BlockHeader.Dynamic.int(.{
|
|
.regular = .{ .final = eos, .kind = .dynamic },
|
|
.hlit = @intCast(dyn_lit_len - 257),
|
|
.hdist = @intCast(dyn_dist_len - 1),
|
|
.hclen = hclen,
|
|
}), 17);
|
|
try c.bit_writer.writeClen(
|
|
hclen,
|
|
clen_values[0..clen_len],
|
|
clen_extra[0..clen_len],
|
|
clen_codes,
|
|
clen_bits,
|
|
);
|
|
break :codes .{
|
|
dyn_codes_buf[0..dyn_lit_len],
|
|
dyn_bits_buf[0..dyn_lit_len],
|
|
dyn_codes_buf[dyn_lit_len..][0..dyn_dist_len],
|
|
dyn_bits_buf[dyn_lit_len..][0..dyn_dist_len],
|
|
};
|
|
} else codes: {
|
|
try c.bit_writer.write(BlockHeader.int(.{ .final = eos, .kind = .fixed }), 3);
|
|
break :codes .{
|
|
&token.fixed_lit_codes,
|
|
&token.fixed_lit_bits,
|
|
&token.fixed_dist_codes,
|
|
&token.fixed_dist_bits,
|
|
};
|
|
};
|
|
|
|
var i: usize = 0;
|
|
while (i != toks.pos) {
|
|
const h: TokenBufferEntryHeader = @bitCast(toks.list[i..][0..2].*);
|
|
i += 2;
|
|
if (h.kind == .bytes) {
|
|
for (toks.list[i..][0..h.data]) |b| {
|
|
try c.bit_writer.write(lit_codes[b], lit_bits[b]);
|
|
}
|
|
i += h.data;
|
|
} else {
|
|
const dist = h.data;
|
|
const len = toks.list[i];
|
|
i += 1;
|
|
const dist_code = token.DistCode.fromVal(dist);
|
|
const len_code = token.LenCode.fromVal(len);
|
|
const dist_val = dist_code.toInt();
|
|
const lit_val = @as(u16, 257) + len_code.toInt();
|
|
|
|
var out: u48 = lit_codes[lit_val];
|
|
var out_bits: u6 = lit_bits[lit_val];
|
|
out |= @shlExact(@as(u20, len - len_code.base()), @intCast(out_bits));
|
|
out_bits += len_code.extraBits();
|
|
|
|
out |= @shlExact(@as(u35, dist_codes[dist_val]), out_bits);
|
|
out_bits += dist_bits[dist_val];
|
|
out |= @shlExact(@as(u48, dist - dist_code.base()), out_bits);
|
|
out_bits += dist_code.extraBits();
|
|
|
|
try c.bit_writer.write(out, out_bits);
|
|
}
|
|
}
|
|
try c.bit_writer.write(lit_codes[256], lit_bits[256]);
|
|
|
|
toks.* = .empty;
|
|
}
|
|
|
|
/// Huffman tree construction.
|
|
///
|
|
/// The approach for building the huffman tree is [taken from zlib]
|
|
/// (https://github.com/madler/zlib/blob/v1.3.1/trees.c#L625) with some modifications.
|
|
const huffman = struct {
|
|
const max_leafs = 286;
|
|
const max_nodes = max_leafs * 2;
|
|
|
|
const Node = struct {
|
|
freq: u16,
|
|
depth: u16,
|
|
|
|
pub const Index = u16;
|
|
|
|
pub fn smaller(a: Node, b: Node) bool {
|
|
return if (a.freq != b.freq) a.freq < b.freq else a.depth < b.depth;
|
|
}
|
|
};
|
|
|
|
fn heapSiftDown(nodes: []Node, heap: []Node.Index, start: usize) void {
|
|
var i = start;
|
|
while (true) {
|
|
var min = i;
|
|
const l = i * 2 + 1;
|
|
const r = l + 1;
|
|
min = if (l < heap.len and nodes[heap[l]].smaller(nodes[heap[min]])) l else min;
|
|
min = if (r < heap.len and nodes[heap[r]].smaller(nodes[heap[min]])) r else min;
|
|
if (i == min) break;
|
|
mem.swap(Node.Index, &heap[i], &heap[min]);
|
|
i = min;
|
|
}
|
|
}
|
|
|
|
fn heapRemoveRoot(nodes: []Node, heap: []Node.Index) void {
|
|
heap[0] = heap[heap.len - 1];
|
|
heapSiftDown(nodes, heap[0 .. heap.len - 1], 0);
|
|
}
|
|
|
|
/// Returns the total bits to encode `freqs` followed by the index of the last non-zero bits.
|
|
/// For `freqs[i]` == 0, `out_codes[i]` will be undefined.
|
|
/// It is asserted `out_bits` is zero-filled.
|
|
/// It is asserted `out_bits.len` is at least a length of
|
|
/// one if ncomplete trees are allowed and two otherwise.
|
|
pub fn build(
|
|
freqs: []const u16,
|
|
out_codes: []u16,
|
|
out_bits: []u4,
|
|
max_bits: u4,
|
|
incomplete_allowed: bool,
|
|
) struct { u32, u16 } {
|
|
assert(out_codes.len - 1 >= @intFromBool(incomplete_allowed));
|
|
// freqs and out_codes are in the loop to assert they are all the same length
|
|
for (freqs, out_codes, out_bits) |_, _, n| assert(n == 0);
|
|
assert(out_codes.len <= @as(u16, 1) << max_bits);
|
|
|
|
// Indexes 0..freqs are leafs, indexes max_leafs.. are internal nodes.
|
|
var tree_nodes: [max_nodes]Node = undefined;
|
|
var tree_parent_nodes: [max_nodes]Node.Index = undefined;
|
|
var nodes_end: u16 = max_leafs;
|
|
// Dual-purpose buffer. Nodes are ordered by least frequency or when equal, least depth.
|
|
// The start is a min heap of level-zero nodes.
|
|
// The end is a sorted buffer of nodes with the greatest first.
|
|
var node_buf: [max_nodes]Node.Index = undefined;
|
|
var heap_end: u16 = 0;
|
|
var sorted_start: u16 = node_buf.len;
|
|
|
|
for (0.., freqs) |n, freq| {
|
|
tree_nodes[n] = .{ .freq = freq, .depth = 0 };
|
|
node_buf[heap_end] = @intCast(n);
|
|
heap_end += @intFromBool(freq != 0);
|
|
}
|
|
|
|
// There must be at least one code at minimum,
|
|
node_buf[heap_end] = 0;
|
|
heap_end += @intFromBool(heap_end == 0);
|
|
// and at least two if incomplete must be avoided.
|
|
if (heap_end == 1 and incomplete_allowed) {
|
|
@branchHint(.unlikely); // LLVM 21 optimizes this branch as the more likely without
|
|
|
|
// Codes must have at least one-bit, so this is a special case.
|
|
out_bits[node_buf[0]] = 1;
|
|
out_codes[node_buf[0]] = 0;
|
|
return .{ freqs[node_buf[0]], node_buf[0] };
|
|
}
|
|
const last_nonzero = @max(node_buf[heap_end - 1], 1); // For heap_end > 1, last is not be 0
|
|
node_buf[heap_end] = @intFromBool(node_buf[0] == 0);
|
|
heap_end += @intFromBool(heap_end == 1);
|
|
|
|
// Heapify the array of frequencies
|
|
const heapify_final = heap_end - 1;
|
|
const heapify_start = (heapify_final - 1) / 2; // Parent of final node
|
|
var heapify_i = heapify_start;
|
|
while (true) {
|
|
heapSiftDown(&tree_nodes, node_buf[0..heap_end], heapify_i);
|
|
if (heapify_i == 0) break;
|
|
heapify_i -= 1;
|
|
}
|
|
|
|
// Build optimal tree. `max_bits` is not enforced yet.
|
|
while (heap_end > 1) {
|
|
const a = node_buf[0];
|
|
heapRemoveRoot(&tree_nodes, node_buf[0..heap_end]);
|
|
heap_end -= 1;
|
|
const b = node_buf[0];
|
|
|
|
sorted_start -= 2;
|
|
node_buf[sorted_start..][0..2].* = .{ b, a };
|
|
|
|
tree_nodes[nodes_end] = .{
|
|
.freq = tree_nodes[a].freq + tree_nodes[b].freq,
|
|
.depth = @max(tree_nodes[a].depth, tree_nodes[b].depth) + 1,
|
|
};
|
|
defer nodes_end += 1;
|
|
tree_parent_nodes[a] = nodes_end;
|
|
tree_parent_nodes[b] = nodes_end;
|
|
|
|
node_buf[0] = nodes_end;
|
|
heapSiftDown(&tree_nodes, node_buf[0..heap_end], 0);
|
|
}
|
|
sorted_start -= 1;
|
|
node_buf[sorted_start] = node_buf[0];
|
|
|
|
var bit_counts: [16]u16 = @splat(0);
|
|
buildBits(out_bits, &bit_counts, &tree_parent_nodes, node_buf[sorted_start..], max_bits);
|
|
return .{ buildValues(freqs, out_codes, out_bits, bit_counts), last_nonzero };
|
|
}
|
|
|
|
fn buildBits(
|
|
out_bits: []u4,
|
|
bit_counts: *[16]u16,
|
|
parent_nodes: *[max_nodes]Node.Index,
|
|
sorted: []Node.Index,
|
|
max_bits: u4,
|
|
) void {
|
|
var internal_node_bits: [max_nodes - max_leafs]u4 = undefined;
|
|
var overflowed: u16 = 0;
|
|
|
|
internal_node_bits[sorted[0] - max_leafs] = 0; // root
|
|
for (sorted[1..]) |i| {
|
|
const parent_bits = internal_node_bits[parent_nodes[i] - max_leafs];
|
|
overflowed += @intFromBool(parent_bits == max_bits);
|
|
const bits = parent_bits + @intFromBool(parent_bits != max_bits);
|
|
bit_counts[bits] += @intFromBool(i < max_leafs);
|
|
(if (i >= max_leafs) &internal_node_bits[i - max_leafs] else &out_bits[i]).* = bits;
|
|
}
|
|
|
|
if (overflowed == 0) {
|
|
@branchHint(.likely);
|
|
return;
|
|
}
|
|
|
|
outer: while (true) {
|
|
var deepest: u4 = max_bits - 1;
|
|
while (bit_counts[deepest] == 0) deepest -= 1;
|
|
while (overflowed != 0) {
|
|
// Insert an internal node under the leaf and move an overflow as its sibling
|
|
bit_counts[deepest] -= 1;
|
|
bit_counts[deepest + 1] += 2;
|
|
// Only overflow moved. Its sibling's depth is one less, however is still >= depth.
|
|
bit_counts[max_bits] -= 1;
|
|
overflowed -= 2;
|
|
|
|
if (overflowed == 0) break :outer;
|
|
deepest += 1;
|
|
if (deepest == max_bits) continue :outer;
|
|
}
|
|
}
|
|
|
|
// Reassign bit lengths
|
|
assert(bit_counts[0] == 0);
|
|
var i: usize = 0;
|
|
for (1.., bit_counts[1..]) |bits, all| {
|
|
var remaining = all;
|
|
while (remaining != 0) {
|
|
defer i += 1;
|
|
if (sorted[i] >= max_leafs) continue;
|
|
out_bits[sorted[i]] = @intCast(bits);
|
|
remaining -= 1;
|
|
}
|
|
}
|
|
assert(for (sorted[i..]) |n| { // all leafs consumed
|
|
if (n < max_leafs) break false;
|
|
} else true);
|
|
}
|
|
|
|
fn buildValues(freqs: []const u16, out_codes: []u16, bits: []u4, bit_counts: [16]u16) u32 {
|
|
var code: u16 = 0;
|
|
var base: [16]u16 = undefined;
|
|
assert(bit_counts[0] == 0);
|
|
for (bit_counts[1..], base[1..]) |c, *b| {
|
|
b.* = code;
|
|
code +%= c;
|
|
code <<= 1;
|
|
}
|
|
var freq_sums: [16]u16 = @splat(0);
|
|
for (out_codes, bits, freqs) |*c, b, f| {
|
|
c.* = @bitReverse(base[b]) >> -%b;
|
|
base[b] += 1; // For `b == 0` this is fine since v is specified to be undefined.
|
|
freq_sums[b] += f;
|
|
}
|
|
return @reduce(.Add, @as(@Vector(16, u32), freq_sums) * std.simd.iota(u32, 16));
|
|
}
|
|
|
|
test build {
|
|
var codes: [8]u16 = undefined;
|
|
var bits: [8]u4 = undefined;
|
|
|
|
const regular_freqs: [8]u16 = .{ 1, 1, 0, 8, 8, 0, 2, 4 };
|
|
// The optimal tree for the above frequencies is
|
|
// 4 1 1
|
|
// \ /
|
|
// 3 2 #
|
|
// \ /
|
|
// 2 8 8 4 #
|
|
// \ / \ /
|
|
// 1 # #
|
|
// \ /
|
|
// 0 #
|
|
bits = @splat(0);
|
|
var n, var lnz = build(®ular_freqs, &codes, &bits, 15, true);
|
|
codes[2] = 0;
|
|
codes[5] = 0;
|
|
try std.testing.expectEqualSlices(u4, &.{ 4, 4, 0, 2, 2, 0, 3, 2 }, &bits);
|
|
try std.testing.expectEqualSlices(u16, &.{
|
|
0b0111, 0b1111, 0, 0b00, 0b10, 0, 0b011, 0b01,
|
|
}, &codes);
|
|
try std.testing.expectEqual(54, n);
|
|
try std.testing.expectEqual(7, lnz);
|
|
// When constrained to 3 bits, it becomes
|
|
// 3 1 1 2 4
|
|
// \ / \ /
|
|
// 2 8 8 # #
|
|
// \ / \ /
|
|
// 1 # #
|
|
// \ /
|
|
// 0 #
|
|
bits = @splat(0);
|
|
n, lnz = build(®ular_freqs, &codes, &bits, 3, true);
|
|
codes[2] = 0;
|
|
codes[5] = 0;
|
|
try std.testing.expectEqualSlices(u4, &.{ 3, 3, 0, 2, 2, 0, 3, 3 }, &bits);
|
|
try std.testing.expectEqualSlices(u16, &.{
|
|
0b001, 0b101, 0, 0b00, 0b10, 0, 0b011, 0b111,
|
|
}, &codes);
|
|
try std.testing.expectEqual(56, n);
|
|
try std.testing.expectEqual(7, lnz);
|
|
|
|
// Empty tree. At least one code should be present
|
|
bits = @splat(0);
|
|
n, lnz = build(&.{ 0, 0 }, codes[0..2], bits[0..2], 15, true);
|
|
try std.testing.expectEqualSlices(u4, &.{ 1, 0 }, bits[0..2]);
|
|
try std.testing.expectEqual(0b0, codes[0]);
|
|
try std.testing.expectEqual(0, n);
|
|
try std.testing.expectEqual(0, lnz);
|
|
|
|
// Check all incompletable frequencies are completed
|
|
for ([_][2]u16{ .{ 0, 0 }, .{ 0, 1 }, .{ 1, 0 } }) |incomplete| {
|
|
// Empty tree. Both codes should be present to prevent incomplete trees
|
|
bits = @splat(0);
|
|
n, lnz = build(&incomplete, codes[0..2], bits[0..2], 15, false);
|
|
try std.testing.expectEqualSlices(u4, &.{ 1, 1 }, bits[0..2]);
|
|
try std.testing.expectEqualSlices(u16, &.{ 0b0, 0b1 }, codes[0..2]);
|
|
try std.testing.expectEqual(incomplete[0] + incomplete[1], n);
|
|
try std.testing.expectEqual(1, lnz);
|
|
}
|
|
|
|
try std.testing.fuzz({}, checkFuzzedBuildFreqs, .{});
|
|
}
|
|
|
|
fn checkFuzzedBuildFreqs(_: void, freqs: []const u8) !void {
|
|
@disableInstrumentation();
|
|
var r: Io.Reader = .fixed(freqs);
|
|
var freqs_limit: u16 = 65535;
|
|
var freqs_buf: [max_leafs]u16 = undefined;
|
|
var nfreqs: u15 = 0;
|
|
|
|
const params: packed struct(u8) {
|
|
max_bits: u4,
|
|
_: u3,
|
|
incomplete_allowed: bool,
|
|
} = @bitCast(r.takeByte() catch 255);
|
|
while (nfreqs != freqs_buf.len) {
|
|
const leb = r.takeLeb128(u16);
|
|
const f = if (leb) |f| @min(f, freqs_limit) else |e| switch (e) {
|
|
error.ReadFailed => unreachable,
|
|
error.EndOfStream => 0,
|
|
error.Overflow => freqs_limit,
|
|
};
|
|
freqs_buf[nfreqs] = f;
|
|
nfreqs += 1;
|
|
freqs_limit -= f;
|
|
if (leb == error.EndOfStream and nfreqs - 1 > @intFromBool(params.incomplete_allowed))
|
|
break;
|
|
}
|
|
|
|
var codes_buf: [max_leafs]u16 = undefined;
|
|
var bits_buf: [max_leafs]u4 = @splat(0);
|
|
const total_bits, const last_nonzero = build(
|
|
freqs_buf[0..nfreqs],
|
|
codes_buf[0..nfreqs],
|
|
bits_buf[0..nfreqs],
|
|
@max(math.log2_int_ceil(u15, nfreqs), params.max_bits),
|
|
params.incomplete_allowed,
|
|
);
|
|
|
|
var has_bitlen_one: bool = false;
|
|
var expected_total_bits: u32 = 0;
|
|
var expected_last_nonzero: ?u16 = null;
|
|
var weighted_sum: u32 = 0;
|
|
for (freqs_buf[0..nfreqs], bits_buf[0..nfreqs], 0..) |f, nb, i| {
|
|
has_bitlen_one = has_bitlen_one or nb == 1;
|
|
weighted_sum += @shlExact(@as(u16, 1), 15 - nb) & ((1 << 15) - 1);
|
|
expected_total_bits += @as(u32, f) * nb;
|
|
if (nb != 0) expected_last_nonzero = @intCast(i);
|
|
}
|
|
|
|
errdefer std.log.err(
|
|
\\ params: {}
|
|
\\ freqs: {any}
|
|
\\ bits: {any}
|
|
\\ # freqs: {}
|
|
\\ max bits: {}
|
|
\\ weighted sum: {}
|
|
\\ has_bitlen_one: {}
|
|
\\ expected/actual total bits: {}/{}
|
|
\\ expected/actual last nonzero: {?}/{}
|
|
++ "\n", .{
|
|
params,
|
|
freqs_buf[0..nfreqs],
|
|
bits_buf[0..nfreqs],
|
|
nfreqs,
|
|
@max(math.log2_int_ceil(u15, nfreqs), params.max_bits),
|
|
weighted_sum,
|
|
has_bitlen_one,
|
|
expected_total_bits,
|
|
total_bits,
|
|
expected_last_nonzero,
|
|
last_nonzero,
|
|
});
|
|
|
|
try std.testing.expectEqual(expected_total_bits, total_bits);
|
|
try std.testing.expectEqual(expected_last_nonzero, last_nonzero);
|
|
if (weighted_sum > 1 << 15)
|
|
return error.OversubscribedHuffmanTree;
|
|
if (weighted_sum < 1 << 15 and
|
|
!(params.incomplete_allowed and has_bitlen_one and weighted_sum == 1 << 14))
|
|
return error.IncompleteHuffmanTree;
|
|
}
|
|
};
|
|
|
|
test {
|
|
_ = huffman;
|
|
}
|
|
|
|
/// [0] is a gradient where the probability of lower values decreases across it
|
|
/// [1] is completely random and hence uncompressable
|
|
fn testingFreqBufs() !*[2][65536]u8 {
|
|
const fbufs = try std.testing.allocator.create([2][65536]u8);
|
|
var prng: std.Random.DefaultPrng = .init(std.testing.random_seed);
|
|
prng.random().bytes(&fbufs[0]);
|
|
prng.random().bytes(&fbufs[1]);
|
|
for (0.., &fbufs[0], fbufs[1]) |i, *grad, rand| {
|
|
const prob = @as(u8, @intCast(255 - i / (fbufs[0].len * 256)));
|
|
grad.* /= @max(1, rand / @max(1, prob));
|
|
}
|
|
return fbufs;
|
|
}
|
|
|
|
fn testingCheckDecompressedMatches(
|
|
flate_bytes: []const u8,
|
|
expected_size: u32,
|
|
expected_hash: flate.Container.Hasher,
|
|
) !void {
|
|
const container: flate.Container = expected_hash;
|
|
var data_hash: flate.Container.Hasher = .init(container);
|
|
var data_size: u32 = 0;
|
|
var flate_r: Io.Reader = .fixed(flate_bytes);
|
|
var deflate_buf: [flate.max_window_len]u8 = undefined;
|
|
var deflate: flate.Decompress = .init(&flate_r, container, &deflate_buf);
|
|
|
|
while (deflate.reader.peekGreedy(1)) |bytes| {
|
|
data_size += @intCast(bytes.len);
|
|
data_hash.update(bytes);
|
|
deflate.reader.toss(bytes.len);
|
|
} else |e| switch (e) {
|
|
error.ReadFailed => return deflate.err.?,
|
|
error.EndOfStream => {},
|
|
}
|
|
|
|
try testingCheckContainerHash(
|
|
expected_size,
|
|
expected_hash,
|
|
data_hash,
|
|
data_size,
|
|
deflate.container_metadata,
|
|
);
|
|
}
|
|
|
|
fn testingCheckContainerHash(
|
|
expected_size: u32,
|
|
expected_hash: flate.Container.Hasher,
|
|
actual_hash: flate.Container.Hasher,
|
|
actual_size: u32,
|
|
actual_meta: flate.Container.Metadata,
|
|
) !void {
|
|
try std.testing.expectEqual(expected_size, actual_size);
|
|
switch (actual_hash) {
|
|
.raw => {},
|
|
.gzip => |gz| {
|
|
const expected_crc = expected_hash.gzip.crc.final();
|
|
try std.testing.expectEqual(expected_size, actual_meta.gzip.count);
|
|
try std.testing.expectEqual(expected_crc, gz.crc.final());
|
|
try std.testing.expectEqual(expected_crc, actual_meta.gzip.crc);
|
|
},
|
|
.zlib => |zl| {
|
|
const expected_adler = expected_hash.zlib.adler;
|
|
try std.testing.expectEqual(expected_adler, zl.adler);
|
|
try std.testing.expectEqual(expected_adler, actual_meta.zlib.adler);
|
|
},
|
|
}
|
|
}
|
|
|
|
const PackedContainer = packed struct(u2) {
|
|
raw: bool,
|
|
other: enum(u1) { gzip, zlib },
|
|
|
|
pub fn val(c: @This()) flate.Container {
|
|
return if (c.raw) .raw else switch (c.other) {
|
|
.gzip => .gzip,
|
|
.zlib => .zlib,
|
|
};
|
|
}
|
|
};
|
|
|
|
test Compress {
|
|
const fbufs = try testingFreqBufs();
|
|
defer if (!builtin.fuzz) std.testing.allocator.destroy(fbufs);
|
|
try std.testing.fuzz(fbufs, testFuzzedCompressInput, .{});
|
|
}
|
|
|
|
fn testFuzzedCompressInput(fbufs: *const [2][65536]u8, input: []const u8) !void {
|
|
var in: Io.Reader = .fixed(input);
|
|
var opts: packed struct(u51) {
|
|
container: PackedContainer,
|
|
buf_size: u16,
|
|
good: u8,
|
|
nice: u8,
|
|
lazy: u8,
|
|
/// Not a `u16` to limit it for performance
|
|
chain: u9,
|
|
} = @bitCast(in.takeLeb128(u51) catch 0);
|
|
var expected_hash: flate.Container.Hasher = .init(opts.container.val());
|
|
var expected_size: u32 = 0;
|
|
|
|
var flate_buf: [128 * 1024]u8 = undefined;
|
|
var flate_w: Writer = .fixed(&flate_buf);
|
|
var deflate_buf: [flate.max_window_len * 2]u8 = undefined;
|
|
var deflate_w = try Compress.init(
|
|
&flate_w,
|
|
deflate_buf[0 .. flate.max_window_len + @as(usize, opts.buf_size)],
|
|
opts.container.val(),
|
|
.{
|
|
.good = @as(u16, opts.good) + 3,
|
|
.nice = @as(u16, opts.nice) + 3,
|
|
.lazy = @as(u16, @min(opts.lazy, opts.nice)) + 3,
|
|
.chain = @max(1, opts.chain, @as(u8, 4) * @intFromBool(opts.good <= opts.lazy)),
|
|
},
|
|
);
|
|
|
|
// It is ensured that more bytes are not written then this to ensure this run
|
|
// does not take too long and that `flate_buf` does not run out of space.
|
|
const flate_buf_blocks = flate_buf.len / block_tokens;
|
|
// Allow a max overhead of 64 bytes per block since the implementation does not gaurauntee it
|
|
// writes store blocks when optimal. This comes from taking less than 32 bytes to write an
|
|
// optimal dynamic block header of mostly bitlen 8 codes and the end of block literal plus
|
|
// `(65536 / 256) / 8`, which is is the maximum number of extra bytes from bitlen 9 codes. An
|
|
// extra 32 bytes is reserved on top of that for container headers and footers.
|
|
const max_size = flate_buf.len - (flate_buf_blocks * 64 + 32);
|
|
|
|
while (true) {
|
|
const data: packed struct(u36) {
|
|
is_rebase: bool,
|
|
is_bytes: bool,
|
|
params: packed union {
|
|
copy: packed struct(u34) {
|
|
len_lo: u5,
|
|
dist: u15,
|
|
len_hi: u4,
|
|
_: u10,
|
|
},
|
|
bytes: packed struct(u34) {
|
|
kind: enum(u1) { gradient, random },
|
|
off_hi: u4,
|
|
len_lo: u10,
|
|
off_mi: u4,
|
|
len_hi: u5,
|
|
off_lo: u8,
|
|
_: u2,
|
|
},
|
|
rebase: packed struct(u34) {
|
|
preserve: u17,
|
|
capacity: u17,
|
|
},
|
|
},
|
|
} = @bitCast(in.takeLeb128(u36) catch |e| switch (e) {
|
|
error.ReadFailed => unreachable,
|
|
error.Overflow => 0,
|
|
error.EndOfStream => break,
|
|
});
|
|
|
|
const buffered = deflate_w.writer.buffered();
|
|
// Required for repeating patterns and since writing from `buffered` is illegal
|
|
var copy_buf: [512]u8 = undefined;
|
|
|
|
if (data.is_rebase) {
|
|
const usable_capacity = deflate_w.writer.buffer.len - rebase_reserved_capacity;
|
|
const preserve = @min(data.params.rebase.preserve, usable_capacity);
|
|
const capacity = @min(data.params.rebase.capacity, usable_capacity -
|
|
@max(rebase_min_preserve, preserve));
|
|
try deflate_w.writer.rebase(preserve, capacity);
|
|
continue;
|
|
}
|
|
|
|
const max_bytes = max_size -| expected_size;
|
|
const bytes = if (!data.is_bytes and buffered.len != 0) bytes: {
|
|
const dist = @min(buffered.len, @as(u32, data.params.copy.dist) + 1);
|
|
const len = @min(
|
|
@max(@shlExact(@as(u9, data.params.copy.len_hi), 5) | data.params.copy.len_lo, 1),
|
|
max_bytes,
|
|
);
|
|
// Reuse the implementation's history. Otherwise our own would need maintained.
|
|
const bytes_start = buffered[buffered.len - dist ..];
|
|
const history_bytes = bytes_start[0..@min(bytes_start.len, len)];
|
|
|
|
@memcpy(copy_buf[0..history_bytes.len], history_bytes);
|
|
const new_history = len - history_bytes.len;
|
|
if (history_bytes.len != len) for ( // check needed for `- dist`
|
|
copy_buf[history_bytes.len..][0..new_history],
|
|
copy_buf[history_bytes.len - dist ..][0..new_history],
|
|
) |*next, prev| {
|
|
next.* = prev;
|
|
};
|
|
break :bytes copy_buf[0..len];
|
|
} else bytes: {
|
|
const off = @shlExact(@as(u16, data.params.bytes.off_hi), 12) |
|
|
@shlExact(@as(u16, data.params.bytes.off_mi), 8) |
|
|
data.params.bytes.off_lo;
|
|
const len = @shlExact(@as(u16, data.params.bytes.len_hi), 10) |
|
|
data.params.bytes.len_lo;
|
|
const fbuf = &fbufs[@intFromEnum(data.params.bytes.kind)];
|
|
break :bytes fbuf[off..][0..@min(len, fbuf.len - off, max_bytes)];
|
|
};
|
|
assert(bytes.len <= max_bytes);
|
|
try deflate_w.writer.writeAll(bytes);
|
|
expected_hash.update(bytes);
|
|
expected_size += @intCast(bytes.len);
|
|
}
|
|
|
|
try deflate_w.writer.flush();
|
|
try testingCheckDecompressedMatches(flate_w.buffered(), expected_size, expected_hash);
|
|
}
|
|
|
|
/// Does not compress data
|
|
pub const Raw = struct {
|
|
/// After `flush` is called, all vtable calls with result in `error.WriteFailed.`
|
|
writer: Writer,
|
|
output: *Writer,
|
|
hasher: flate.Container.Hasher,
|
|
|
|
const max_block_size: u16 = 65535;
|
|
const full_header: [5]u8 = .{
|
|
BlockHeader.int(.{ .final = false, .kind = .stored }),
|
|
255,
|
|
255,
|
|
0,
|
|
0,
|
|
};
|
|
|
|
/// While there is no minimum buffer size, it is recommended
|
|
/// to be at least `flate.max_window_len` for optimal output.
|
|
pub fn init(output: *Writer, buffer: []u8, container: flate.Container) Writer.Error!Raw {
|
|
try output.writeAll(container.header());
|
|
return .{
|
|
.writer = .{
|
|
.buffer = buffer,
|
|
.vtable = &.{
|
|
.drain = Raw.drain,
|
|
.flush = Raw.flush,
|
|
.rebase = Raw.rebase,
|
|
},
|
|
},
|
|
.output = output,
|
|
.hasher = .init(container),
|
|
};
|
|
}
|
|
|
|
fn drain(w: *Writer, data: []const []const u8, splat: usize) Writer.Error!usize {
|
|
errdefer w.* = .failing;
|
|
const r: *Raw = @fieldParentPtr("writer", w);
|
|
const min_block = @min(w.buffer.len, max_block_size);
|
|
const pattern = data[data.len - 1];
|
|
var partial_header: [5]u8 = undefined;
|
|
|
|
var vecs: [16][]const u8 = undefined;
|
|
var vecs_n: usize = 0;
|
|
const data_bytes = Writer.countSplat(data, splat);
|
|
const total_bytes = w.end + data_bytes;
|
|
var rem_bytes = total_bytes;
|
|
var rem_splat = splat;
|
|
var rem_data = data;
|
|
var rem_data_elem: []const u8 = w.buffered();
|
|
|
|
assert(rem_bytes > min_block);
|
|
while (rem_bytes > min_block) { // not >= to allow `min_block` blocks to be marked as final
|
|
// also, it handles the case of `min_block` being zero (no buffer)
|
|
const block_size: u16 = @min(rem_bytes, max_block_size);
|
|
rem_bytes -= block_size;
|
|
|
|
if (vecs_n == vecs.len) {
|
|
try r.output.writeVecAll(&vecs);
|
|
vecs_n = 0;
|
|
}
|
|
vecs[vecs_n] = if (block_size == 65535)
|
|
&full_header
|
|
else header: {
|
|
partial_header[0] = BlockHeader.int(.{ .final = false, .kind = .stored });
|
|
mem.writeInt(u16, partial_header[1..3], block_size, .little);
|
|
mem.writeInt(u16, partial_header[3..5], ~block_size, .little);
|
|
break :header &partial_header;
|
|
};
|
|
vecs_n += 1;
|
|
|
|
var block_limit: Io.Limit = .limited(block_size);
|
|
while (true) {
|
|
if (vecs_n == vecs.len) {
|
|
try r.output.writeVecAll(&vecs);
|
|
vecs_n = 0;
|
|
}
|
|
|
|
const vec = block_limit.sliceConst(rem_data_elem);
|
|
vecs[vecs_n] = vec;
|
|
vecs_n += 1;
|
|
r.hasher.update(vec);
|
|
|
|
const is_pattern = rem_splat != splat and vec.len == pattern.len;
|
|
if (is_pattern) assert(pattern.len != 0); // exceeded countSplat
|
|
|
|
if (!is_pattern or rem_splat == 0 or pattern.len > @intFromEnum(block_limit) / 2) {
|
|
rem_data_elem = rem_data_elem[vec.len..];
|
|
block_limit = block_limit.subtract(vec.len).?;
|
|
|
|
if (rem_data_elem.len == 0) {
|
|
rem_data_elem = rem_data[0];
|
|
if (rem_data.len != 1) {
|
|
rem_data = rem_data[1..];
|
|
} else if (rem_splat != 0) {
|
|
rem_splat -= 1;
|
|
} else {
|
|
// All of `data` has been consumed.
|
|
assert(block_limit == .nothing);
|
|
assert(rem_bytes == 0);
|
|
// Since `rem_bytes` and `block_limit` are zero, these won't be used.
|
|
rem_data = undefined;
|
|
rem_data_elem = undefined;
|
|
rem_splat = undefined;
|
|
}
|
|
}
|
|
if (block_limit == .nothing) break;
|
|
} else {
|
|
const out_splat = @intFromEnum(block_limit) / pattern.len;
|
|
assert(out_splat >= 2);
|
|
|
|
try r.output.writeSplatAll(vecs[0..vecs_n], out_splat);
|
|
for (1..out_splat) |_| r.hasher.update(vec);
|
|
|
|
vecs_n = 0;
|
|
block_limit = block_limit.subtract(pattern.len * out_splat).?;
|
|
if (rem_splat >= out_splat) {
|
|
// `out_splat` contains `rem_data`, however one more needs subtracted
|
|
// anyways since the next pattern is also being taken.
|
|
rem_splat -= out_splat;
|
|
} else {
|
|
// All of `data` has been consumed.
|
|
assert(block_limit == .nothing);
|
|
assert(rem_bytes == 0);
|
|
// Since `rem_bytes` and `block_limit` are zero, these won't be used.
|
|
rem_data = undefined;
|
|
rem_data_elem = undefined;
|
|
rem_splat = undefined;
|
|
}
|
|
if (block_limit == .nothing) break;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (vecs_n != 0) { // can be the case if a splat was sent
|
|
try r.output.writeVecAll(vecs[0..vecs_n]);
|
|
}
|
|
|
|
if (rem_bytes > data_bytes) {
|
|
assert(rem_bytes - data_bytes == rem_data_elem.len);
|
|
assert(&rem_data_elem[0] == &w.buffer[total_bytes - rem_bytes]);
|
|
}
|
|
return w.consume(total_bytes - rem_bytes);
|
|
}
|
|
|
|
fn flush(w: *Writer) Writer.Error!void {
|
|
defer w.* = .failing;
|
|
try Raw.rebaseInner(w, 0, w.buffer.len, true);
|
|
}
|
|
|
|
fn rebase(w: *Writer, preserve: usize, capacity: usize) Writer.Error!void {
|
|
errdefer w.* = .failing;
|
|
try Raw.rebaseInner(w, preserve, capacity, false);
|
|
}
|
|
|
|
fn rebaseInner(w: *Writer, preserve: usize, capacity: usize, eos: bool) Writer.Error!void {
|
|
const r: *Raw = @fieldParentPtr("writer", w);
|
|
assert(preserve + capacity <= w.buffer.len);
|
|
if (eos) assert(capacity == w.buffer.len);
|
|
|
|
var partial_header: [5]u8 = undefined;
|
|
var footer_buf: [8]u8 = undefined;
|
|
const preserved = @min(w.end, preserve);
|
|
var remaining = w.buffer[0 .. w.end - preserved];
|
|
|
|
var vecs: [16][]const u8 = undefined;
|
|
var vecs_n: usize = 0;
|
|
while (remaining.len > max_block_size) { // not >= so there is always a block down below
|
|
if (vecs_n == vecs.len) {
|
|
try r.output.writeVecAll(&vecs);
|
|
vecs_n = 0;
|
|
}
|
|
vecs[vecs_n + 0] = &full_header;
|
|
vecs[vecs_n + 1] = remaining[0..max_block_size];
|
|
r.hasher.update(vecs[vecs_n + 1]);
|
|
vecs_n += 2;
|
|
remaining = remaining[max_block_size..];
|
|
}
|
|
|
|
// eos check required for empty block
|
|
if (w.buffer.len - (remaining.len + preserved) < capacity or eos) {
|
|
// A partial write is necessary to reclaim enough buffer space
|
|
const block_size: u16 = @intCast(remaining.len);
|
|
partial_header[0] = BlockHeader.int(.{ .final = eos, .kind = .stored });
|
|
mem.writeInt(u16, partial_header[1..3], block_size, .little);
|
|
mem.writeInt(u16, partial_header[3..5], ~block_size, .little);
|
|
|
|
if (vecs_n == vecs.len) {
|
|
try r.output.writeVecAll(&vecs);
|
|
vecs_n = 0;
|
|
}
|
|
vecs[vecs_n + 0] = &partial_header;
|
|
vecs[vecs_n + 1] = remaining[0..block_size];
|
|
r.hasher.update(vecs[vecs_n + 1]);
|
|
vecs_n += 2;
|
|
remaining = remaining[block_size..];
|
|
assert(remaining.len == 0);
|
|
|
|
if (eos and r.hasher != .raw) {
|
|
// the footer is done here instead of `flush` so it can be included in the vector
|
|
var footer_w: Writer = .fixed(&footer_buf);
|
|
r.hasher.writeFooter(&footer_w) catch unreachable;
|
|
assert(footer_w.end != 0);
|
|
|
|
if (vecs_n == vecs.len) {
|
|
try r.output.writeVecAll(&vecs);
|
|
return r.output.writeAll(footer_w.buffered());
|
|
} else {
|
|
vecs[vecs_n] = footer_w.buffered();
|
|
vecs_n += 1;
|
|
}
|
|
}
|
|
}
|
|
|
|
try r.output.writeVecAll(vecs[0..vecs_n]);
|
|
_ = w.consume(w.end - preserved - remaining.len);
|
|
}
|
|
};
|
|
|
|
test Raw {
|
|
const data_buf = try std.testing.allocator.create([4 * 65536]u8);
|
|
defer if (!builtin.fuzz) std.testing.allocator.destroy(data_buf);
|
|
var prng: std.Random.DefaultPrng = .init(std.testing.random_seed);
|
|
prng.random().bytes(data_buf);
|
|
try std.testing.fuzz(data_buf, testFuzzedRawInput, .{});
|
|
}
|
|
|
|
fn countVec(data: []const []const u8) usize {
|
|
var bytes: usize = 0;
|
|
for (data) |d| bytes += d.len;
|
|
return bytes;
|
|
}
|
|
|
|
fn testFuzzedRawInput(data_buf: *const [4 * 65536]u8, input: []const u8) !void {
|
|
const HashedStoreWriter = struct {
|
|
writer: Writer,
|
|
state: enum {
|
|
header,
|
|
block_header,
|
|
block_body,
|
|
final_block_body,
|
|
footer,
|
|
end,
|
|
},
|
|
block_remaining: u16,
|
|
container: flate.Container,
|
|
data_hash: flate.Container.Hasher,
|
|
data_size: usize,
|
|
footer_hash: u32,
|
|
footer_size: u32,
|
|
|
|
pub fn init(buf: []u8, container: flate.Container) @This() {
|
|
return .{
|
|
.writer = .{
|
|
.vtable = &.{
|
|
.drain = @This().drain,
|
|
.flush = @This().flush,
|
|
},
|
|
.buffer = buf,
|
|
},
|
|
.state = .header,
|
|
.block_remaining = 0,
|
|
.container = container,
|
|
.data_hash = .init(container),
|
|
.data_size = 0,
|
|
.footer_hash = undefined,
|
|
.footer_size = undefined,
|
|
};
|
|
}
|
|
|
|
/// Note that this implementation is somewhat dependent on the implementation of
|
|
/// `Raw` by expecting headers / footers to be continous in data elements. It
|
|
/// also expects the header to be the same as `flate.Container.header` and not
|
|
/// for multiple streams to be concatenated.
|
|
fn drain(w: *Writer, data: []const []const u8, splat: usize) Writer.Error!usize {
|
|
errdefer w.* = .failing;
|
|
var h: *@This() = @fieldParentPtr("writer", w);
|
|
|
|
var rem_splat = splat;
|
|
var rem_data = data;
|
|
var rem_data_elem: []const u8 = w.buffered();
|
|
|
|
data_loop: while (true) {
|
|
const wanted = switch (h.state) {
|
|
.header => h.container.headerSize(),
|
|
.block_header => 5,
|
|
.block_body, .final_block_body => h.block_remaining,
|
|
.footer => h.container.footerSize(),
|
|
.end => 1,
|
|
};
|
|
|
|
if (wanted != 0) {
|
|
while (rem_data_elem.len == 0) {
|
|
rem_data_elem = rem_data[0];
|
|
if (rem_data.len != 1) {
|
|
rem_data = rem_data[1..];
|
|
} else {
|
|
if (rem_splat == 0) {
|
|
break :data_loop;
|
|
} else {
|
|
rem_splat -= 1;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
const bytes = Io.Limit.limited(wanted).sliceConst(rem_data_elem);
|
|
rem_data_elem = rem_data_elem[bytes.len..];
|
|
|
|
switch (h.state) {
|
|
.header => {
|
|
if (bytes.len < wanted)
|
|
return error.WriteFailed; // header eos
|
|
if (!mem.eql(u8, bytes, h.container.header()))
|
|
return error.WriteFailed; // wrong header
|
|
h.state = .block_header;
|
|
},
|
|
.block_header => {
|
|
if (bytes.len < wanted)
|
|
return error.WriteFailed; // store block header eos
|
|
const header: BlockHeader = @bitCast(@as(u3, @truncate(bytes[0])));
|
|
if (header.kind != .stored)
|
|
return error.WriteFailed; // non-store block
|
|
const len = mem.readInt(u16, bytes[1..3], .little);
|
|
const nlen = mem.readInt(u16, bytes[3..5], .little);
|
|
if (nlen != ~len)
|
|
return error.WriteFailed; // wrong nlen
|
|
h.block_remaining = len;
|
|
h.state = if (!header.final) .block_body else .final_block_body;
|
|
},
|
|
.block_body, .final_block_body => {
|
|
h.data_hash.update(bytes);
|
|
h.data_size += bytes.len;
|
|
h.block_remaining -= @intCast(bytes.len);
|
|
if (h.block_remaining == 0) {
|
|
h.state = if (h.state != .final_block_body) .block_header else .footer;
|
|
}
|
|
},
|
|
.footer => {
|
|
if (bytes.len < wanted)
|
|
return error.WriteFailed; // footer eos
|
|
switch (h.container) {
|
|
.raw => {},
|
|
.gzip => {
|
|
h.footer_hash = mem.readInt(u32, bytes[0..4], .little);
|
|
h.footer_size = mem.readInt(u32, bytes[4..8], .little);
|
|
},
|
|
.zlib => {
|
|
h.footer_hash = mem.readInt(u32, bytes[0..4], .big);
|
|
},
|
|
}
|
|
h.state = .end;
|
|
},
|
|
.end => return error.WriteFailed, // data past end
|
|
}
|
|
}
|
|
|
|
w.end = 0;
|
|
return Writer.countSplat(data, splat);
|
|
}
|
|
|
|
fn flush(w: *Writer) Writer.Error!void {
|
|
defer w.* = .failing; // Clears buffer even if state hasn't reached `end`
|
|
_ = try @This().drain(w, &.{""}, 0);
|
|
}
|
|
};
|
|
|
|
var in: Io.Reader = .fixed(input);
|
|
const opts: packed struct(u19) {
|
|
container: PackedContainer,
|
|
buf_len: u17,
|
|
} = @bitCast(in.takeLeb128(u19) catch 0);
|
|
var output: HashedStoreWriter = .init(&.{}, opts.container.val());
|
|
var r_buf: [2 * 65536]u8 = undefined;
|
|
var r: Raw = try .init(
|
|
&output.writer,
|
|
r_buf[0 .. opts.buf_len +% flate.max_window_len],
|
|
opts.container.val(),
|
|
);
|
|
|
|
var data_base: u18 = 0;
|
|
var expected_hash: flate.Container.Hasher = .init(opts.container.val());
|
|
var expected_size: u32 = 0;
|
|
var vecs: [32][]const u8 = undefined;
|
|
var vecs_n: usize = 0;
|
|
|
|
while (in.seek != in.end) {
|
|
const VecInfo = packed struct(u58) {
|
|
output: bool,
|
|
/// If set, `data_len` and `splat` are reinterpreted as `capacity`
|
|
/// and `preserve_len` respectively and `output` is treated as set.
|
|
rebase: bool,
|
|
block_aligning_len: bool,
|
|
block_aligning_splat: bool,
|
|
data_len: u18,
|
|
splat: u18,
|
|
data_off: u18,
|
|
};
|
|
var vec_info: VecInfo = @bitCast(in.takeLeb128(u58) catch |e| switch (e) {
|
|
error.ReadFailed => unreachable,
|
|
error.Overflow, error.EndOfStream => 0,
|
|
});
|
|
|
|
{
|
|
const buffered = r.writer.buffered().len + countVec(vecs[0..vecs_n]);
|
|
const to_align = mem.alignForwardAnyAlign(usize, buffered, Raw.max_block_size) - buffered;
|
|
assert((buffered + to_align) % Raw.max_block_size == 0);
|
|
|
|
if (vec_info.block_aligning_len) {
|
|
vec_info.data_len = @intCast(to_align);
|
|
} else if (vec_info.block_aligning_splat and vec_info.data_len != 0 and
|
|
to_align % vec_info.data_len == 0)
|
|
{
|
|
vec_info.splat = @divExact(@as(u18, @intCast(to_align)), vec_info.data_len) -% 1;
|
|
}
|
|
}
|
|
|
|
var splat = if (vec_info.output and !vec_info.rebase) vec_info.splat +% 1 else 1;
|
|
add_vec: {
|
|
if (vec_info.rebase) break :add_vec;
|
|
if (expected_size +| math.mulWide(u18, vec_info.data_len, splat) >
|
|
10 * (1 << 16))
|
|
{
|
|
// Skip this vector to avoid this test taking too long.
|
|
// 10 maximum sized blocks is choosen as the limit since it is two more
|
|
// than the maximum the implementation can output in one drain.
|
|
splat = 1;
|
|
break :add_vec;
|
|
}
|
|
|
|
vecs[vecs_n] = data_buf[@min(
|
|
data_base +% vec_info.data_off,
|
|
data_buf.len - vec_info.data_len,
|
|
)..][0..vec_info.data_len];
|
|
|
|
data_base +%= vec_info.data_len +% 3; // extra 3 to help catch aliasing bugs
|
|
|
|
for (0..splat) |_| expected_hash.update(vecs[vecs_n]);
|
|
expected_size += @as(u32, @intCast(vecs[vecs_n].len)) * splat;
|
|
vecs_n += 1;
|
|
}
|
|
|
|
const want_drain = vecs_n == vecs.len or vec_info.output or vec_info.rebase or
|
|
in.seek == in.end;
|
|
if (want_drain and vecs_n != 0) {
|
|
try r.writer.writeSplatAll(vecs[0..vecs_n], splat);
|
|
vecs_n = 0;
|
|
} else assert(splat == 1);
|
|
|
|
if (vec_info.rebase) {
|
|
try r.writer.rebase(vec_info.data_len, @min(
|
|
r.writer.buffer.len -| vec_info.data_len,
|
|
vec_info.splat,
|
|
));
|
|
}
|
|
}
|
|
|
|
try r.writer.flush();
|
|
try output.writer.flush();
|
|
|
|
try std.testing.expectEqual(.end, output.state);
|
|
try std.testing.expectEqual(expected_size, output.data_size);
|
|
switch (output.data_hash) {
|
|
.raw => {},
|
|
.gzip => |gz| {
|
|
const expected_crc = expected_hash.gzip.crc.final();
|
|
try std.testing.expectEqual(expected_crc, gz.crc.final());
|
|
try std.testing.expectEqual(expected_crc, output.footer_hash);
|
|
try std.testing.expectEqual(expected_size, output.footer_size);
|
|
},
|
|
.zlib => |zl| {
|
|
const expected_adler = expected_hash.zlib.adler;
|
|
try std.testing.expectEqual(expected_adler, zl.adler);
|
|
try std.testing.expectEqual(expected_adler, output.footer_hash);
|
|
},
|
|
}
|
|
}
|
|
|
|
/// Only performs huffman compression on data, does no matching.
|
|
pub const Huffman = struct {
|
|
writer: Writer,
|
|
bit_writer: BitWriter,
|
|
hasher: flate.Container.Hasher,
|
|
|
|
const max_tokens: u16 = 65535 - 1; // one is reserved for EOF
|
|
|
|
/// While there is no minimum buffer size, it is recommended
|
|
/// to be at least `flate.max_window_len` to improve compression.
|
|
///
|
|
/// It is asserted `output` has a capacity of at least 8 bytes.
|
|
pub fn init(output: *Writer, buffer: []u8, container: flate.Container) Writer.Error!Huffman {
|
|
assert(output.buffer.len > 8);
|
|
|
|
try output.writeAll(container.header());
|
|
return .{
|
|
.writer = .{
|
|
.buffer = buffer,
|
|
.vtable = &.{
|
|
.drain = Huffman.drain,
|
|
.flush = Huffman.flush,
|
|
.rebase = Huffman.rebase,
|
|
},
|
|
},
|
|
.bit_writer = .init(output),
|
|
.hasher = .init(container),
|
|
};
|
|
}
|
|
|
|
fn drain(w: *Writer, data: []const []const u8, splat: usize) Writer.Error!usize {
|
|
{
|
|
//std.debug.print("drain {} (buffered)", .{w.buffered().len});
|
|
//for (data) |d| std.debug.print("\n\t+ {}", .{d.len});
|
|
//std.debug.print(" x {}\n\n", .{splat});
|
|
}
|
|
|
|
const h: *Huffman = @fieldParentPtr("writer", w);
|
|
const min_block = @min(w.buffer.len, max_tokens);
|
|
const pattern = data[data.len - 1];
|
|
|
|
const data_bytes = Writer.countSplat(data, splat);
|
|
const total_bytes = w.end + data_bytes;
|
|
var rem_bytes = total_bytes;
|
|
var rem_splat = splat;
|
|
var rem_data = data;
|
|
var rem_data_elem: []const u8 = w.buffered();
|
|
|
|
assert(rem_bytes > min_block);
|
|
while (rem_bytes > min_block) { // not >= to allow `min_block` blocks to be marked as final
|
|
// also, it handles the case of `min_block` being zero (no buffer)
|
|
const block_size: u16 = @min(rem_bytes, max_tokens);
|
|
rem_bytes -= block_size;
|
|
|
|
// Count frequencies
|
|
comptime assert(max_tokens != 65535);
|
|
var freqs: [257]u16 = @splat(0);
|
|
freqs[256] = 1;
|
|
|
|
const start_splat = rem_splat;
|
|
const start_data = rem_data;
|
|
const start_data_elem = rem_data_elem;
|
|
|
|
var block_limit: Io.Limit = .limited(block_size);
|
|
while (true) {
|
|
const bytes = block_limit.sliceConst(rem_data_elem);
|
|
const is_pattern = rem_splat != splat and bytes.len == pattern.len;
|
|
|
|
const mul = if (!is_pattern) 1 else @intFromEnum(block_limit) / pattern.len;
|
|
assert(mul != 0);
|
|
if (is_pattern) assert(mul <= rem_splat + 1); // one more for `rem_data`
|
|
|
|
for (bytes) |b| freqs[b] += @intCast(mul);
|
|
rem_data_elem = rem_data_elem[bytes.len..];
|
|
block_limit = block_limit.subtract(bytes.len * mul).?;
|
|
|
|
if (rem_data_elem.len == 0) {
|
|
rem_data_elem = rem_data[0];
|
|
if (rem_data.len != 1) {
|
|
rem_data = rem_data[1..];
|
|
} else if (rem_splat >= mul) {
|
|
// if the counter was not the pattern, `mul` is always one, otherwise,
|
|
// `mul` contains `rem_data`, however one more needs subtracted anyways
|
|
// since the next pattern is also being taken.
|
|
rem_splat -= mul;
|
|
} else {
|
|
// All of `data` has been consumed.
|
|
assert(block_limit == .nothing);
|
|
assert(rem_bytes == 0);
|
|
// Since `rem_bytes` and `block_limit` are zero, these won't be used.
|
|
rem_data = undefined;
|
|
rem_data_elem = undefined;
|
|
rem_splat = undefined;
|
|
}
|
|
}
|
|
if (block_limit == .nothing) break;
|
|
}
|
|
|
|
// Output block
|
|
rem_splat = start_splat;
|
|
rem_data = start_data;
|
|
rem_data_elem = start_data_elem;
|
|
block_limit = .limited(block_size);
|
|
|
|
var codes_buf: CodesBuf = .init;
|
|
if (try h.outputHeader(&freqs, &codes_buf, block_size, false)) |table| {
|
|
while (true) {
|
|
const bytes = block_limit.sliceConst(rem_data_elem);
|
|
rem_data_elem = rem_data_elem[bytes.len..];
|
|
block_limit = block_limit.subtract(bytes.len).?;
|
|
|
|
h.hasher.update(bytes);
|
|
for (bytes) |b| {
|
|
try h.bit_writer.write(table.codes[b], table.bits[b]);
|
|
}
|
|
|
|
if (rem_data_elem.len == 0) {
|
|
rem_data_elem = rem_data[0];
|
|
if (rem_data.len != 1) {
|
|
rem_data = rem_data[1..];
|
|
} else if (rem_splat != 0) {
|
|
rem_splat -= 1;
|
|
} else {
|
|
// All of `data` has been consumed.
|
|
assert(block_limit == .nothing);
|
|
assert(rem_bytes == 0);
|
|
// Since `rem_bytes` and `block_limit` are zero, these won't be used.
|
|
rem_data = undefined;
|
|
rem_data_elem = undefined;
|
|
rem_splat = undefined;
|
|
}
|
|
}
|
|
if (block_limit == .nothing) break;
|
|
}
|
|
try h.bit_writer.write(table.codes[256], table.bits[256]);
|
|
} else while (true) {
|
|
// Store block
|
|
|
|
// Write data that is not a full vector element
|
|
const in_pattern = rem_splat != splat;
|
|
const vec_elem_i, const in_data =
|
|
@subWithOverflow(data.len - (rem_data.len - @intFromBool(in_pattern)), 1);
|
|
const is_elem = in_data == 0 and data[vec_elem_i].len == rem_data_elem.len;
|
|
|
|
if (!is_elem or rem_data_elem.len > @intFromEnum(block_limit)) {
|
|
block_limit = block_limit.subtract(rem_data_elem.len) orelse {
|
|
try h.bit_writer.output.writeAll(rem_data_elem[0..@intFromEnum(block_limit)]);
|
|
h.hasher.update(rem_data_elem[0..@intFromEnum(block_limit)]);
|
|
rem_data_elem = rem_data_elem[@intFromEnum(block_limit)..];
|
|
assert(rem_data_elem.len != 0);
|
|
break;
|
|
};
|
|
try h.bit_writer.output.writeAll(rem_data_elem);
|
|
h.hasher.update(rem_data_elem);
|
|
} else {
|
|
// Put `rem_data_elem` back in `rem_data`
|
|
if (!in_pattern) {
|
|
rem_data = data[vec_elem_i..];
|
|
} else {
|
|
rem_splat += 1;
|
|
}
|
|
}
|
|
rem_data_elem = undefined; // it is always updated below
|
|
|
|
// Send through as much of the original vector as possible
|
|
var vec_n: usize = 0;
|
|
var vlimit = block_limit;
|
|
const vec_splat = while (rem_data[vec_n..].len != 1) {
|
|
vlimit = vlimit.subtract(rem_data[vec_n].len) orelse break 1;
|
|
vec_n += 1;
|
|
} else vec_splat: {
|
|
// For `pattern.len == 0`, the value of `vec_splat` does not matter.
|
|
const vec_splat = @intFromEnum(vlimit) / @max(1, pattern.len);
|
|
if (pattern.len != 0) assert(vec_splat <= rem_splat + 1);
|
|
vlimit = vlimit.subtract(pattern.len * vec_splat).?;
|
|
vec_n += 1;
|
|
break :vec_splat vec_splat;
|
|
};
|
|
|
|
const n = if (vec_n != 0) n: {
|
|
assert(@intFromEnum(block_limit) - @intFromEnum(vlimit) ==
|
|
Writer.countSplat(rem_data[0..vec_n], vec_splat));
|
|
break :n try h.bit_writer.output.writeSplat(rem_data[0..vec_n], vec_splat);
|
|
} else 0; // Still go into the case below to advance the vector
|
|
block_limit = block_limit.subtract(n).?;
|
|
var consumed: Io.Limit = .limited(n);
|
|
|
|
while (rem_data.len != 1) {
|
|
const elem = rem_data[0];
|
|
rem_data = rem_data[1..];
|
|
consumed = consumed.subtract(elem.len) orelse {
|
|
h.hasher.update(elem[0..@intFromEnum(consumed)]);
|
|
rem_data_elem = elem[@intFromEnum(consumed)..];
|
|
break;
|
|
};
|
|
h.hasher.update(elem);
|
|
} else {
|
|
if (pattern.len == 0) {
|
|
// All of `data` has been consumed. However, the general
|
|
// case below does not work since it divides by zero.
|
|
assert(consumed == .nothing);
|
|
assert(block_limit == .nothing);
|
|
assert(rem_bytes == 0);
|
|
// Since `rem_bytes` and `block_limit` are zero, these won't be used.
|
|
rem_splat = undefined;
|
|
rem_data = undefined;
|
|
rem_data_elem = undefined;
|
|
break;
|
|
}
|
|
|
|
const splatted = @intFromEnum(consumed) / pattern.len;
|
|
const partial = @intFromEnum(consumed) % pattern.len;
|
|
for (0..splatted) |_| h.hasher.update(pattern);
|
|
h.hasher.update(pattern[0..partial]);
|
|
|
|
const taken_splat = splatted + 1;
|
|
if (rem_splat >= taken_splat) {
|
|
rem_splat -= taken_splat;
|
|
rem_data_elem = pattern[partial..];
|
|
} else {
|
|
// All of `data` has been consumed.
|
|
assert(partial == 0);
|
|
assert(block_limit == .nothing);
|
|
assert(rem_bytes == 0);
|
|
// Since `rem_bytes` and `block_limit` are zero, these won't be used.
|
|
rem_data = undefined;
|
|
rem_data_elem = undefined;
|
|
rem_splat = undefined;
|
|
}
|
|
}
|
|
|
|
if (block_limit == .nothing) break;
|
|
}
|
|
}
|
|
|
|
if (rem_bytes > data_bytes) {
|
|
assert(rem_bytes - data_bytes == rem_data_elem.len);
|
|
assert(&rem_data_elem[0] == &w.buffer[total_bytes - rem_bytes]);
|
|
}
|
|
return w.consume(total_bytes - rem_bytes);
|
|
}
|
|
|
|
fn flush(w: *Writer) Writer.Error!void {
|
|
defer w.* = .failing;
|
|
const h: *Huffman = @fieldParentPtr("writer", w);
|
|
try Huffman.rebaseInner(w, 0, w.buffer.len, true);
|
|
try h.bit_writer.output.rebase(0, 1);
|
|
h.bit_writer.byteAlign();
|
|
try h.hasher.writeFooter(h.bit_writer.output);
|
|
}
|
|
|
|
fn rebase(w: *Writer, preserve: usize, capacity: usize) Writer.Error!void {
|
|
errdefer w.* = .failing;
|
|
try Huffman.rebaseInner(w, preserve, capacity, false);
|
|
}
|
|
|
|
fn rebaseInner(w: *Writer, preserve: usize, capacity: usize, eos: bool) Writer.Error!void {
|
|
const h: *Huffman = @fieldParentPtr("writer", w);
|
|
assert(preserve + capacity <= w.buffer.len);
|
|
if (eos) assert(capacity == w.buffer.len);
|
|
|
|
const preserved = @min(w.end, preserve);
|
|
var remaining = w.buffer[0 .. w.end - preserved];
|
|
while (remaining.len > max_tokens) { // not >= so there is always a block down below
|
|
const bytes = remaining[0..max_tokens];
|
|
remaining = remaining[max_tokens..];
|
|
try h.outputBytes(bytes, false);
|
|
}
|
|
|
|
// eos check required for empty block
|
|
if (w.buffer.len - (remaining.len + preserved) < capacity or eos) {
|
|
const bytes = remaining;
|
|
remaining = &.{};
|
|
try h.outputBytes(bytes, eos);
|
|
}
|
|
|
|
_ = w.consume(w.end - preserved - remaining.len);
|
|
}
|
|
|
|
fn outputBytes(h: *Huffman, bytes: []const u8, eos: bool) Writer.Error!void {
|
|
comptime assert(max_tokens != 65535);
|
|
assert(bytes.len <= max_tokens);
|
|
var freqs: [257]u16 = @splat(0);
|
|
freqs[256] = 1;
|
|
for (bytes) |b| freqs[b] += 1;
|
|
h.hasher.update(bytes);
|
|
|
|
var codes_buf: CodesBuf = .init;
|
|
if (try h.outputHeader(&freqs, &codes_buf, @intCast(bytes.len), eos)) |table| {
|
|
for (bytes) |b| {
|
|
try h.bit_writer.write(table.codes[b], table.bits[b]);
|
|
}
|
|
try h.bit_writer.write(table.codes[256], table.bits[256]);
|
|
} else {
|
|
try h.bit_writer.output.writeAll(bytes);
|
|
}
|
|
}
|
|
|
|
const CodesBuf = struct {
|
|
dyn_codes: [258]u16,
|
|
dyn_bits: [258]u4,
|
|
|
|
pub const init: CodesBuf = .{
|
|
.dyn_codes = @as([257]u16, undefined) ++ .{0},
|
|
.dyn_bits = @as([257]u4, @splat(0)) ++ .{1},
|
|
};
|
|
};
|
|
|
|
/// Returns null if the block is stored.
|
|
fn outputHeader(
|
|
h: *Huffman,
|
|
freqs: *const [257]u16,
|
|
buf: *CodesBuf,
|
|
bytes: u16,
|
|
eos: bool,
|
|
) Writer.Error!?struct {
|
|
codes: *const [257]u16,
|
|
bits: *const [257]u4,
|
|
} {
|
|
assert(freqs[256] == 1);
|
|
const dyn_codes_bitsize, _ = huffman.build(
|
|
freqs,
|
|
buf.dyn_codes[0..257],
|
|
buf.dyn_bits[0..257],
|
|
15,
|
|
true,
|
|
);
|
|
|
|
var clen_values: [258]u8 = undefined;
|
|
var clen_extra: [258]u8 = undefined;
|
|
var clen_freqs: [19]u16 = @splat(0);
|
|
const clen_len, const clen_extra_bitsize = buildClen(
|
|
&buf.dyn_bits,
|
|
&clen_values,
|
|
&clen_extra,
|
|
&clen_freqs,
|
|
);
|
|
|
|
var clen_codes: [19]u16 = undefined;
|
|
var clen_bits: [19]u4 = @splat(0);
|
|
const clen_codes_bitsize, _ = huffman.build(
|
|
&clen_freqs,
|
|
&clen_codes,
|
|
&clen_bits,
|
|
7,
|
|
false,
|
|
);
|
|
const hclen = clenHlen(clen_freqs);
|
|
|
|
const dynamic_bitsize = @as(u32, 14) +
|
|
(4 + @as(u6, hclen)) * 3 + clen_codes_bitsize + clen_extra_bitsize +
|
|
dyn_codes_bitsize;
|
|
const fixed_bitsize = n: {
|
|
const freq7 = 1; // eos
|
|
var freq9: u16 = 0;
|
|
for (freqs[144..256]) |f| freq9 += f;
|
|
const freq8: u16 = bytes - freq9;
|
|
break :n @as(u32, freq7) * 7 + @as(u32, freq8) * 8 + @as(u32, freq9) * 9;
|
|
};
|
|
const stored_bitsize = n: {
|
|
const stored_align_bits = -%(h.bit_writer.buffered_n +% 3);
|
|
break :n stored_align_bits + @as(u32, 32) + @as(u32, bytes) * 8;
|
|
};
|
|
|
|
//std.debug.print("@ {}{{{}}} ", .{ h.bit_writer.output.end, h.bit_writer.buffered_n });
|
|
//std.debug.print("#{} -> s {} f {} d {}\n", .{ bytes, stored_bitsize, fixed_bitsize, dynamic_bitsize });
|
|
|
|
if (stored_bitsize <= @min(dynamic_bitsize, fixed_bitsize)) {
|
|
try h.bit_writer.write(BlockHeader.int(.{ .kind = .stored, .final = eos }), 3);
|
|
try h.bit_writer.output.rebase(0, 5);
|
|
h.bit_writer.byteAlign();
|
|
h.bit_writer.output.writeInt(u16, bytes, .little) catch unreachable;
|
|
h.bit_writer.output.writeInt(u16, ~bytes, .little) catch unreachable;
|
|
return null;
|
|
}
|
|
|
|
if (fixed_bitsize <= dynamic_bitsize) {
|
|
try h.bit_writer.write(BlockHeader.int(.{ .final = eos, .kind = .fixed }), 3);
|
|
return .{
|
|
.codes = token.fixed_lit_codes[0..257],
|
|
.bits = token.fixed_lit_bits[0..257],
|
|
};
|
|
} else {
|
|
try h.bit_writer.write(BlockHeader.Dynamic.int(.{
|
|
.regular = .{ .final = eos, .kind = .dynamic },
|
|
.hlit = 0,
|
|
.hdist = 0,
|
|
.hclen = hclen,
|
|
}), 17);
|
|
try h.bit_writer.writeClen(
|
|
hclen,
|
|
clen_values[0..clen_len],
|
|
clen_extra[0..clen_len],
|
|
clen_codes,
|
|
clen_bits,
|
|
);
|
|
return .{ .codes = buf.dyn_codes[0..257], .bits = buf.dyn_bits[0..257] };
|
|
}
|
|
}
|
|
};
|
|
|
|
test Huffman {
|
|
const fbufs = try testingFreqBufs();
|
|
defer if (!builtin.fuzz) std.testing.allocator.destroy(fbufs);
|
|
try std.testing.fuzz(fbufs, testFuzzedHuffmanInput, .{});
|
|
}
|
|
|
|
/// This function is derived from `testFuzzedRawInput` with a few changes for fuzzing `Huffman`.
|
|
fn testFuzzedHuffmanInput(fbufs: *const [2][65536]u8, input: []const u8) !void {
|
|
var in: Io.Reader = .fixed(input);
|
|
const opts: packed struct(u19) {
|
|
container: PackedContainer,
|
|
buf_len: u17,
|
|
} = @bitCast(in.takeLeb128(u19) catch 0);
|
|
var flate_buf: [2 * 65536]u8 = undefined;
|
|
var flate_w: Writer = .fixed(&flate_buf);
|
|
var h_buf: [2 * 65536]u8 = undefined;
|
|
var h: Huffman = try .init(
|
|
&flate_w,
|
|
h_buf[0 .. opts.buf_len +% flate.max_window_len],
|
|
opts.container.val(),
|
|
);
|
|
|
|
var expected_hash: flate.Container.Hasher = .init(opts.container.val());
|
|
var expected_size: u32 = 0;
|
|
var vecs: [32][]const u8 = undefined;
|
|
var vecs_n: usize = 0;
|
|
|
|
while (in.seek != in.end) {
|
|
const VecInfo = packed struct(u55) {
|
|
output: bool,
|
|
/// If set, `data_len` and `splat` are reinterpreted as `capacity`
|
|
/// and `preserve_len` respectively and `output` is treated as set.
|
|
rebase: bool,
|
|
block_aligning_len: bool,
|
|
block_aligning_splat: bool,
|
|
data_off_hi: u8,
|
|
random_data: u1,
|
|
data_len: u16,
|
|
splat: u18,
|
|
/// This is less useful as each value is part of the same gradient 'step'
|
|
data_off_lo: u8,
|
|
};
|
|
var vec_info: VecInfo = @bitCast(in.takeLeb128(u55) catch |e| switch (e) {
|
|
error.ReadFailed => unreachable,
|
|
error.Overflow, error.EndOfStream => 0,
|
|
});
|
|
|
|
{
|
|
const buffered = h.writer.buffered().len + countVec(vecs[0..vecs_n]);
|
|
const to_align = mem.alignForwardAnyAlign(usize, buffered, Huffman.max_tokens) - buffered;
|
|
assert((buffered + to_align) % Huffman.max_tokens == 0);
|
|
|
|
if (vec_info.block_aligning_len) {
|
|
vec_info.data_len = @intCast(to_align);
|
|
} else if (vec_info.block_aligning_splat and vec_info.data_len != 0 and
|
|
to_align % vec_info.data_len == 0)
|
|
{
|
|
vec_info.splat = @divExact(@as(u18, @intCast(to_align)), vec_info.data_len) -% 1;
|
|
}
|
|
}
|
|
|
|
var splat = if (vec_info.output and !vec_info.rebase) vec_info.splat +% 1 else 1;
|
|
add_vec: {
|
|
if (vec_info.rebase) break :add_vec;
|
|
if (expected_size +| math.mulWide(u18, vec_info.data_len, splat) > 4 * (1 << 16)) {
|
|
// Skip this vector to avoid this test taking too long.
|
|
splat = 1;
|
|
break :add_vec;
|
|
}
|
|
|
|
const data_buf = &fbufs[vec_info.random_data];
|
|
vecs[vecs_n] = data_buf[@min(
|
|
(@as(u16, vec_info.data_off_hi) << 8) | vec_info.data_off_lo,
|
|
data_buf.len - vec_info.data_len,
|
|
)..][0..vec_info.data_len];
|
|
|
|
for (0..splat) |_| expected_hash.update(vecs[vecs_n]);
|
|
expected_size += @as(u32, @intCast(vecs[vecs_n].len)) * splat;
|
|
vecs_n += 1;
|
|
}
|
|
|
|
const want_drain = vecs_n == vecs.len or vec_info.output or vec_info.rebase or
|
|
in.seek == in.end;
|
|
if (want_drain and vecs_n != 0) {
|
|
var n = h.writer.buffered().len + Writer.countSplat(vecs[0..vecs_n], splat);
|
|
const oos = h.writer.writeSplatAll(vecs[0..vecs_n], splat) == error.WriteFailed;
|
|
n -= h.writer.buffered().len;
|
|
const block_lim = math.divCeil(usize, n, Huffman.max_tokens) catch unreachable;
|
|
const lim = flate_w.end + 6 * block_lim + n; // 6 since block header may span two bytes
|
|
if (flate_w.end > lim) return error.OverheadTooLarge;
|
|
if (oos) return;
|
|
|
|
vecs_n = 0;
|
|
} else assert(splat == 1);
|
|
|
|
if (vec_info.rebase) {
|
|
const old_end = flate_w.end;
|
|
var n = h.writer.buffered().len;
|
|
const oos = h.writer.rebase(vec_info.data_len, @min(
|
|
h.writer.buffer.len -| vec_info.data_len,
|
|
vec_info.splat,
|
|
)) == error.WriteFailed;
|
|
n -= h.writer.buffered().len;
|
|
const block_lim = math.divCeil(usize, n, Huffman.max_tokens) catch unreachable;
|
|
const lim = old_end + 6 * block_lim + n; // 6 since block header may span two bytes
|
|
if (flate_w.end > lim) return error.OverheadTooLarge;
|
|
if (oos) return;
|
|
}
|
|
}
|
|
|
|
{
|
|
const old_end = flate_w.end;
|
|
const n = h.writer.buffered().len;
|
|
const oos = h.writer.flush() == error.WriteFailed;
|
|
assert(h.writer.buffered().len == 0);
|
|
const block_lim = @max(1, math.divCeil(usize, n, Huffman.max_tokens) catch unreachable);
|
|
const lim = old_end + 6 * block_lim + n + opts.container.val().footerSize();
|
|
if (flate_w.end > lim) return error.OverheadTooLarge;
|
|
if (oos) return;
|
|
}
|
|
|
|
try testingCheckDecompressedMatches(flate_w.buffered(), expected_size, expected_hash);
|
|
}
|