glibc/sysdeps/ieee754/flt-32/s_llrintf.c
Xiaolin Tang a1981ecbfd Use GCC builtins for llrint functions if desired.
This patch is using the corresponding GCC builtin for llrintf, llrint,
llrintl and llrintf128 if the USE_FUNCTION_BUILTIN macros are defined to one
in math-use-builtins-function.h.

Co-Authored-By: Xi Ruoyao <xry111@xry111.site>
2022-11-29 16:00:28 +08:00

94 lines
2.3 KiB
C

/* Round argument to nearest integral value according to current rounding
direction.
Copyright (C) 1997-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <fenv.h>
#include <limits.h>
#include <math.h>
#include <math-narrow-eval.h>
#include <math_private.h>
#include <libm-alias-float.h>
#include <fix-fp-int-convert-overflow.h>
#include <math-use-builtins.h>
long long int
__llrintf (float x)
{
#if USE_LLRINTF_BUILTIN
return __builtin_llrintf (x);
#else
/* Use generic implementation. */
static const float two23[2] =
{
8.3886080000e+06, /* 0x4B000000 */
-8.3886080000e+06, /* 0xCB000000 */
};
int32_t j0;
uint32_t i0;
float w;
float t;
long long int result;
int sx;
GET_FLOAT_WORD (i0, x);
sx = i0 >> 31;
j0 = ((i0 >> 23) & 0xff) - 0x7f;
i0 &= 0x7fffff;
i0 |= 0x800000;
if (j0 < (int32_t) (sizeof (long long int) * 8) - 1)
{
if (j0 >= 23)
result = (long long int) i0 << (j0 - 23);
else
{
w = math_narrow_eval (two23[sx] + x);
t = w - two23[sx];
GET_FLOAT_WORD (i0, t);
j0 = ((i0 >> 23) & 0xff) - 0x7f;
i0 &= 0x7fffff;
i0 |= 0x800000;
result = (j0 < 0 ? 0 : i0 >> (23 - j0));
}
}
else
{
#ifdef FE_INVALID
/* The number is too large. Unless it rounds to LLONG_MIN,
FE_INVALID must be raised and the return value is
unspecified. */
if (FIX_FLT_LLONG_CONVERT_OVERFLOW && x != (float) LLONG_MIN)
{
feraiseexcept (FE_INVALID);
return sx == 0 ? LLONG_MAX : LLONG_MIN;
}
#endif
return (long long int) x;
}
return sx ? -result : result;
#endif /* ! USE_LLRINTF_BUILTIN */
}
libm_alias_float (__llrint, llrint)