cosmopolitan/third_party/compiler_rt/fixunsxfsi.c

49 lines
1.5 KiB
C

/* clang-format off */
/* ===-- fixunsxfsi.c - Implement __fixunsxfsi -----------------------------===
*
* 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 __fixunsxfsi 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 unsigned int, rounding toward zero.
* Negative values all become zero.
*/
/* Assumption: long double is an intel 80 bit floating point type padded with 6 bytes
* su_int is a 32 bit integral type
* value in long double is representable in su_int or is negative
*/
/* 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 su_int
__fixunsxfsi(long double a)
{
long_double_bits fb;
fb.f = a;
int e = (fb.u.high.s.low & 0x00007FFF) - 16383;
if (e < 0 || (fb.u.high.s.low & 0x00008000))
return 0;
if ((unsigned)e > sizeof(su_int) * CHAR_BIT)
return ~(su_int)0;
return fb.u.low.s.high >> (31 - e);
}
#endif /* !_ARCH_PPC */