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d29871977f
We already have a LICENSE file that covers the Zig Standard Library. We no longer need to remind everyone that the license is MIT in every single file. Previously this was introduced to clarify the situation for a fork of Zig that made Zig's LICENSE file harder to find, and replaced it with their own license that required annual payments to their company. However that fork now appears to be dead. So there is no need to reinforce the copyright notice in every single file.
57 lines
1.6 KiB
Zig
57 lines
1.6 KiB
Zig
const std = @import("std");
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const is_test = std.builtin.is_test;
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const native_endian = std.Target.current.cpu.arch.endian();
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// Ported from
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// https://github.com/llvm/llvm-project/blob/llvmorg-9.0.0/compiler-rt/lib/builtins/muldi3.c
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const dwords = extern union {
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all: i64,
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s: switch (native_endian) {
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.Little => extern struct {
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low: u32,
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high: u32,
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},
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.Big => extern struct {
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high: u32,
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low: u32,
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},
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},
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};
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fn __muldsi3(a: u32, b: u32) i64 {
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@setRuntimeSafety(is_test);
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const bits_in_word_2 = @sizeOf(i32) * 8 / 2;
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const lower_mask = (~@as(u32, 0)) >> bits_in_word_2;
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var r: dwords = undefined;
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r.s.low = (a & lower_mask) *% (b & lower_mask);
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var t: u32 = r.s.low >> bits_in_word_2;
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r.s.low &= lower_mask;
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t += (a >> bits_in_word_2) *% (b & lower_mask);
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r.s.low +%= (t & lower_mask) << bits_in_word_2;
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r.s.high = t >> bits_in_word_2;
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t = r.s.low >> bits_in_word_2;
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r.s.low &= lower_mask;
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t +%= (b >> bits_in_word_2) *% (a & lower_mask);
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r.s.low +%= (t & lower_mask) << bits_in_word_2;
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r.s.high +%= t >> bits_in_word_2;
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r.s.high +%= (a >> bits_in_word_2) *% (b >> bits_in_word_2);
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return r.all;
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}
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pub fn __muldi3(a: i64, b: i64) callconv(.C) i64 {
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@setRuntimeSafety(is_test);
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const x = dwords{ .all = a };
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const y = dwords{ .all = b };
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var r = dwords{ .all = __muldsi3(x.s.low, y.s.low) };
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r.s.high +%= x.s.high *% y.s.low +% x.s.low *% y.s.high;
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return r.all;
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}
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test "import muldi3" {
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_ = @import("muldi3_test.zig");
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}
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