cosmopolitan/third_party/compiler_rt/multi3.c
Justine Tunney 7e0a09feec
Mint APE Loader v1.5
This change ports APE Loader to Linux AARCH64, so that Raspberry Pi
users can run programs like redbean, without the executable needing
to modify itself. Progress has also slipped into this change on the
issue of making progress better conforming to user expectations and
industry standards regarding which symbols we're allowed to declare
2023-07-26 13:54:49 -07:00

61 lines
1.7 KiB
C

/* clang-format off */
/* ===-- multi3.c - Implement __multi3 -------------------------------------===
*
* The LLVM Compiler Infrastructure
*
* This file is dual licensed under the MIT and the University of Illinois Open
* Source Licenses. See LICENSE.TXT for details.
*
* ===----------------------------------------------------------------------===
__static_yoink("huge_compiler_rt_license");
* This file implements __multi3 for the compiler_rt library.
*
* ===----------------------------------------------------------------------===
*/
#include "third_party/compiler_rt/int_lib.h"
#ifdef CRT_HAS_128BIT
/* Returns: a * b */
static
ti_int
__mulddi3(du_int a, du_int b)
{
twords r;
const int bits_in_dword_2 = (int)(sizeof(di_int) * CHAR_BIT) / 2;
const du_int lower_mask = (du_int)~0 >> bits_in_dword_2;
r.s.low = (a & lower_mask) * (b & lower_mask);
du_int t = 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;
}
/* Returns: a * b */
COMPILER_RT_ABI ti_int
__multi3(ti_int a, ti_int b)
{
twords x;
x.all = a;
twords y;
y.all = b;
twords r;
r.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;
}
#endif /* CRT_HAS_128BIT */