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const builtin = @import("builtin");
const std = @import("std");
const testing = std.testing;
const common = @import("common.zig");
const native_endian = builtin.cpu.arch.endian();
pub const panic = common.panic;
comptime {
@export(&__mulsi3, .{ .name = "__mulsi3", .linkage = common.linkage, .visibility = common.visibility });
if (common.want_aeabi) {
@export(&__aeabi_lmul, .{ .name = "__aeabi_lmul", .linkage = common.linkage, .visibility = common.visibility });
} else {
@export(&__muldi3, .{ .name = "__muldi3", .linkage = common.linkage, .visibility = common.visibility });
}
if (common.want_windows_v2u64_abi) {
@export(&__multi3_windows_x86_64, .{ .name = "__multi3", .linkage = common.linkage, .visibility = common.visibility });
} else {
@export(&__multi3, .{ .name = "__multi3", .linkage = common.linkage, .visibility = common.visibility });
}
}
pub fn __mulsi3(a: i32, b: i32) callconv(.c) i32 {
var ua: u32 = @bitCast(a);
var ub: u32 = @bitCast(b);
var r: u32 = 0;
while (ua > 0) {
if ((ua & 1) != 0) r +%= ub;
ua >>= 1;
ub <<= 1;
}
return @bitCast(r);
}
pub fn __muldi3(a: i64, b: i64) callconv(.c) i64 {
return mulX(i64, a, b);
}
fn __aeabi_lmul(a: i64, b: i64) callconv(.{ .arm_aapcs = .{} }) i64 {
return mulX(i64, a, b);
}
inline fn mulX(comptime T: type, a: T, b: T) T {
const word_t = common.HalveInt(T, false);
const x = word_t{ .all = a };
const y = word_t{ .all = b };
var r = switch (T) {
i64, i128 => word_t{ .all = muldXi(word_t.HalfT, x.s.low, y.s.low) },
else => unreachable,
};
r.s.high +%= x.s.high *% y.s.low +% x.s.low *% y.s.high;
return r.all;
}
fn DoubleInt(comptime T: type) type {
return switch (T) {
u32 => i64,
u64 => i128,
i32 => i64,
i64 => i128,
else => unreachable,
};
}
fn muldXi(comptime T: type, a: T, b: T) DoubleInt(T) {
const DT = DoubleInt(T);
const word_t = common.HalveInt(DT, false);
const bits_in_word_2 = @sizeOf(T) * 8 / 2;
const lower_mask = (~@as(T, 0)) >> bits_in_word_2;
var r: word_t = undefined;
r.s.low = (a & lower_mask) *% (b & lower_mask);
var t: T = r.s.low >> bits_in_word_2;
r.s.low &= lower_mask;
t += (a >> bits_in_word_2) *% (b & lower_mask);
r.s.low +%= (t & lower_mask) << bits_in_word_2;
r.s.high = t >> bits_in_word_2;
t = r.s.low >> bits_in_word_2;
r.s.low &= lower_mask;
t +%= (b >> bits_in_word_2) *% (a & lower_mask);
r.s.low +%= (t & lower_mask) << bits_in_word_2;
r.s.high +%= t >> bits_in_word_2;
r.s.high +%= (a >> bits_in_word_2) *% (b >> bits_in_word_2);
return r.all;
}
pub fn __multi3(a: i128, b: i128) callconv(.c) i128 {
return mulX(i128, a, b);
}
const v2u64 = @Vector(2, u64);
fn __multi3_windows_x86_64(a: v2u64, b: v2u64) callconv(.c) v2u64 {
return @bitCast(mulX(i128, @as(i128, @bitCast(a)), @as(i128, @bitCast(b))));
}
test {
_ = @import("mulXi3_test.zig");
}
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