glibc/sysdeps/ieee754/flt-32/s_truncf.c
Stefan Liebler 1ac9c1cf87 Use GCC builtins for trunc functions if desired.
This patch is using the corresponding GCC builtin for truncf, trunc,
truncl and truncf128 if the USE_FUNCTION_BUILTIN macros are defined to one
in math-use-builtins.h.

This is the case for s390 if build with at least --march=z196 --mzarch.
Otherwise the generic implementation is used.  The code of the generic
implementation is not changed.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
2019-12-11 15:12:17 +01:00

62 lines
1.6 KiB
C

/* Truncate argument to nearest integral value not larger than the argument.
Copyright (C) 1997-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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/>. */
#define NO_MATH_REDIRECT
#include <math.h>
#include <math_private.h>
#include <libm-alias-float.h>
#include <math-use-builtins.h>
float
__truncf (float x)
{
#if USE_TRUNCF_BUILTIN
return __builtin_truncf (x);
#else
/* Use generic implementation. */
int32_t i0, j0;
int sx;
GET_FLOAT_WORD (i0, x);
sx = i0 & 0x80000000;
j0 = ((i0 >> 23) & 0xff) - 0x7f;
if (j0 < 23)
{
if (j0 < 0)
/* The magnitude of the number is < 1 so the result is +-0. */
SET_FLOAT_WORD (x, sx);
else
SET_FLOAT_WORD (x, sx | (i0 & ~(0x007fffff >> j0)));
}
else
{
if (j0 == 0x80)
/* x is inf or NaN. */
return x + x;
}
return x;
#endif /* ! USE_TRUNCF_BUILTIN */
}
#ifndef __truncf
libm_alias_float (__trunc, trunc)
#endif