cosmopolitan/third_party/compiler_rt/muldi3.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 */
/* ===-- muldi3.c - Implement __muldi3 -------------------------------------===
*
* 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.
*
* ===----------------------------------------------------------------------===
*
* This file implements __muldi3 for the compiler_rt library.
*
* ===----------------------------------------------------------------------===
*/
__static_yoink("huge_compiler_rt_license");
#include "third_party/compiler_rt/int_lib.h"
/* Returns: a * b */
static
di_int
__muldsi3(su_int a, su_int b)
{
dwords r;
const int bits_in_word_2 = (int)(sizeof(si_int) * CHAR_BIT) / 2;
const su_int lower_mask = (su_int)~0 >> bits_in_word_2;
r.s.low = (a & lower_mask) * (b & lower_mask);
su_int 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;
}
/* Returns: a * b */
COMPILER_RT_ABI di_int
__muldi3(di_int a, di_int b)
{
dwords x;
x.all = a;
dwords y;
y.all = b;
dwords r;
r.all = __muldsi3(x.s.low, y.s.low);
r.s.high += x.s.high * y.s.low + x.s.low * y.s.high;
return r.all;
}
#if defined(__ARM_EABI__)
AEABI_RTABI di_int __aeabi_lmul(di_int a, di_int b) COMPILER_RT_ALIAS(__muldi3);
#endif