mirror of
https://codeberg.org/ziglang/zig.git
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ec95e00e28
stage2: change logic for detecting whether the main package is inside
the std package. Previously it relied on realpath() which is not portable.
This uses resolve() which is how imports already work.
* stage2: fix cleanup bug when creating Module
* flatten lib/std/special/* to lib/*
- this was motivated by making main_pkg_is_inside_std false for
compiler_rt & friends.
* rename "mini libc" to "universal libc"
72 lines
2.2 KiB
Zig
72 lines
2.2 KiB
Zig
const builtin = @import("builtin");
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const std = @import("std");
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const math = std.math;
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// mulo - multiplication overflow
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// * return a*%b.
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// * return if a*b overflows => 1 else => 0
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// - muloXi4_genericSmall as default
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// - muloXi4_genericFast for 2*bitsize <= usize
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inline fn muloXi4_genericSmall(comptime ST: type, a: ST, b: ST, overflow: *c_int) ST {
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@setRuntimeSafety(builtin.is_test);
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overflow.* = 0;
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const min = math.minInt(ST);
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var res: ST = a *% b;
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// Hacker's Delight section Overflow subsection Multiplication
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// case a=-2^{31}, b=-1 problem, because
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// on some machines a*b = -2^{31} with overflow
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// Then -2^{31}/-1 overflows and any result is possible.
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// => check with a<0 and b=-2^{31}
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if ((a < 0 and b == min) or (a != 0 and @divTrunc(res, a) != b))
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overflow.* = 1;
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return res;
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}
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inline fn muloXi4_genericFast(comptime ST: type, a: ST, b: ST, overflow: *c_int) ST {
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@setRuntimeSafety(builtin.is_test);
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overflow.* = 0;
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const EST = switch (ST) {
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i32 => i64,
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i64 => i128,
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i128 => i256,
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else => unreachable,
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};
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const min = math.minInt(ST);
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const max = math.maxInt(ST);
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var res: EST = @as(EST, a) * @as(EST, b);
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//invariant: -2^{bitwidth(EST)} < res < 2^{bitwidth(EST)-1}
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if (res < min or max < res)
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overflow.* = 1;
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return @truncate(ST, res);
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}
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pub fn __mulosi4(a: i32, b: i32, overflow: *c_int) callconv(.C) i32 {
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if (2 * @bitSizeOf(i32) <= @bitSizeOf(usize)) {
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return muloXi4_genericFast(i32, a, b, overflow);
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} else {
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return muloXi4_genericSmall(i32, a, b, overflow);
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}
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}
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pub fn __mulodi4(a: i64, b: i64, overflow: *c_int) callconv(.C) i64 {
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if (2 * @bitSizeOf(i64) <= @bitSizeOf(usize)) {
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return muloXi4_genericFast(i64, a, b, overflow);
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} else {
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return muloXi4_genericSmall(i64, a, b, overflow);
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}
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}
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pub fn __muloti4(a: i128, b: i128, overflow: *c_int) callconv(.C) i128 {
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if (2 * @bitSizeOf(i128) <= @bitSizeOf(usize)) {
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return muloXi4_genericFast(i128, a, b, overflow);
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} else {
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return muloXi4_genericSmall(i128, a, b, overflow);
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}
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}
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test {
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_ = @import("mulosi4_test.zig");
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_ = @import("mulodi4_test.zig");
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_ = @import("muloti4_test.zig");
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}
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