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const builtin = @import("builtin");
const compiler_rt = @import("../compiler_rt.zig");
// Ported from git@github.com:llvm-project/llvm-project-20170507.git
// ae684fad6d34858c014c94da69c15e7774a633c3
// 2018-08-13
pub extern fn __multi3(a: i128, b: i128) i128 {
@setRuntimeSafety(builtin.is_test);
const x = twords{ .all = a };
const y = twords{ .all = b };
var r = twords{ .all = __mulddi3(x.s.low, y.s.low) };
r.s.high +%= x.s.high *% y.s.low +% x.s.low *% y.s.high;
return r.all;
}
const v128 = @Vector(2, u64);
pub extern fn __multi3_windows_x86_64(a: v128, b: v128) v128 {
return @bitCast(v128, @inlineCall(__multi3, @bitCast(i128, a), @bitCast(i128, b)));
}
fn __mulddi3(a: u64, b: u64) i128 {
const bits_in_dword_2 = (@sizeOf(i64) * 8) / 2;
const lower_mask = ~u64(0) >> bits_in_dword_2;
var r: twords = undefined;
r.s.low = (a & lower_mask) *% (b & lower_mask);
var t: u64 = r.s.low >> bits_in_dword_2;
r.s.low &= lower_mask;
t +%= (a >> bits_in_dword_2) *% (b & lower_mask);
r.s.low +%= (t & lower_mask) << bits_in_dword_2;
r.s.high = t >> bits_in_dword_2;
t = r.s.low >> bits_in_dword_2;
r.s.low &= lower_mask;
t +%= (b >> bits_in_dword_2) *% (a & lower_mask);
r.s.low +%= (t & lower_mask) << bits_in_dword_2;
r.s.high +%= t >> bits_in_dword_2;
r.s.high +%= (a >> bits_in_dword_2) *% (b >> bits_in_dword_2);
return r.all;
}
const twords = extern union {
all: i128,
s: S,
const S = if (builtin.endian == builtin.Endian.Little)
struct {
low: u64,
high: u64,
}
else
struct {
high: u64,
low: u64,
};
};
test "import multi3" {
_ = @import("multi3_test.zig");
}
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