cosmopolitan/third_party/compiler_rt/fixxfti.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

58 lines
1.7 KiB
C

/* clang-format off */
/* ===-- fixxfti.c - Implement __fixxfti -----------------------------------===
*
* 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 __fixxfti for the compiler_rt library.
*
* ===----------------------------------------------------------------------===
*/
#include "libc/math.h"
#if !(LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024)
__static_yoink("huge_compiler_rt_license");
#include "third_party/compiler_rt/int_lib.h"
#ifdef CRT_HAS_128BIT
/* Returns: convert a to a signed long long, rounding toward zero. */
/* Assumption: long double is an intel 80 bit floating point type padded with 6 bytes
* ti_int is a 128 bit integral type
* value in long double is representable in ti_int
*/
/* gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee eeee |
* 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm
*/
COMPILER_RT_ABI ti_int
__fixxfti(long double a)
{
const ti_int ti_max = (ti_int)((~(tu_int)0) / 2);
const ti_int ti_min = -ti_max - 1;
long_double_bits fb;
fb.f = a;
int e = (fb.u.high.s.low & 0x00007FFF) - 16383;
if (e < 0)
return 0;
ti_int s = -(si_int)((fb.u.high.s.low & 0x00008000) >> 15);
ti_int r = fb.u.low.all;
if ((unsigned)e >= sizeof(ti_int) * CHAR_BIT)
return a > 0 ? ti_max : ti_min;
if (e > 63)
r <<= (e - 63);
else
r >>= (63 - e);
return (r ^ s) - s;
}
#endif /* CRT_HAS_128BIT */
#endif /* long double is long */