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https://codeberg.org/ziglang/zig.git
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b31a91bbef
Also, accepting `align(1)` pointers ensures that the alignment is safety checked rather than assumed.
52 lines
2 KiB
Zig
52 lines
2 KiB
Zig
const std = @import("std");
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const builtin = @import("builtin");
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const common = @import("common.zig");
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const udivmod = @import("udivmodei4.zig").divmod;
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comptime {
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@export(&__divei4, .{ .name = "__divei4", .linkage = common.linkage, .visibility = common.visibility });
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@export(&__modei4, .{ .name = "__modei4", .linkage = common.linkage, .visibility = common.visibility });
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}
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const endian = builtin.cpu.arch.endian();
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inline fn limb(x: []u32, i: usize) *u32 {
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return if (endian == .little) &x[i] else &x[x.len - 1 - i];
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}
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inline fn neg(x: []u32) void {
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var ov: u1 = 1;
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for (0..x.len) |limb_index| {
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const l = limb(x, limb_index);
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l.*, ov = @addWithOverflow(~l.*, ov);
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}
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}
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/// Mutates the arguments!
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fn divmod(q: ?[]u32, r: ?[]u32, u: []u32, v: []u32) !void {
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const u_sign: i32 = @bitCast(u[u.len - 1]);
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const v_sign: i32 = @bitCast(v[v.len - 1]);
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if (u_sign < 0) neg(u);
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if (v_sign < 0) neg(v);
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try @call(.always_inline, udivmod, .{ q, r, u, v });
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if (q) |x| if (u_sign ^ v_sign < 0) neg(x);
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if (r) |x| if (u_sign < 0) neg(x);
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}
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pub fn __divei4(q_p: [*]u8, u_p: [*]u8, v_p: [*]u8, bits: usize) callconv(.c) void {
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@setRuntimeSafety(builtin.is_test);
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const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
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const q: []u32 = @ptrCast(@alignCast(q_p[0..byte_size]));
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const u: []u32 = @ptrCast(@alignCast(u_p[0..byte_size]));
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const v: []u32 = @ptrCast(@alignCast(v_p[0..byte_size]));
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@call(.always_inline, divmod, .{ q, null, u, v }) catch unreachable;
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}
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pub fn __modei4(r_p: [*]u8, u_p: [*]u8, v_p: [*]u8, bits: usize) callconv(.c) void {
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@setRuntimeSafety(builtin.is_test);
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const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
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const r: []u32 = @ptrCast(@alignCast(r_p[0..byte_size]));
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const u: []u32 = @ptrCast(@alignCast(u_p[0..byte_size]));
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const v: []u32 = @ptrCast(@alignCast(v_p[0..byte_size]));
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@call(.always_inline, divmod, .{ null, r, u, v }) catch unreachable;
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}
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