cosmopolitan/third_party/compiler_rt/fixxfdi.c

52 lines
1.6 KiB
C

/* clang-format off */
/* ===-- fixxfdi.c - Implement __fixxfdi -----------------------------------===
*
* 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 __fixxfdi for the compiler_rt library.
*
* ===----------------------------------------------------------------------===
*/
STATIC_YOINK("huge_compiler_rt_license");
#if !_ARCH_PPC
#include "third_party/compiler_rt/int_lib.h"
/* 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
* di_int is a 64 bit integral type
* value in long double is representable in di_int (no range checking performed)
*/
/* 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 di_int
__fixxfdi(long double a)
{
const di_int di_max = (di_int)((~(du_int)0) / 2);
const di_int di_min = -di_max - 1;
long_double_bits fb;
fb.f = a;
int e = (fb.u.high.s.low & 0x00007FFF) - 16383;
if (e < 0)
return 0;
if ((unsigned)e >= sizeof(di_int) * CHAR_BIT)
return a > 0 ? di_max : di_min;
di_int s = -(si_int)((fb.u.high.s.low & 0x00008000) >> 15);
di_int r = fb.u.low.all;
r = (du_int)r >> (63 - e);
return (r ^ s) - s;
}
#endif /* !_ARCH_PPC */