glibc/sysdeps/ieee754/flt-32/s_floorf.c
Stefan Liebler 6c1b6a5e8c Use GCC builtins for floor functions if desired.
This patch is using the corresponding GCC builtin for floorf, floor,
floorl and floorf128 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 15:12:16 +01:00

63 lines
1.4 KiB
C

/* s_floorf.c -- float version of s_floor.c.
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
*/
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/*
* floorf(x)
* Return x rounded toward -inf to integral value
* Method:
* Bit twiddling.
*/
#define NO_MATH_REDIRECT
#include <math.h>
#include <math_private.h>
#include <libm-alias-float.h>
#include <math-use-builtins.h>
float
__floorf(float x)
{
#if USE_FLOORF_BUILTIN
return __builtin_floorf (x);
#else
/* Use generic implementation. */
int32_t i0,j0;
uint32_t i;
GET_FLOAT_WORD(i0,x);
j0 = ((i0>>23)&0xff)-0x7f;
if(j0<23) {
if(j0<0) {
/* return 0*sign(x) if |x|<1 */
if(i0>=0) {i0=0;}
else if((i0&0x7fffffff)!=0)
{ i0=0xbf800000;}
} else {
i = (0x007fffff)>>j0;
if((i0&i)==0) return x; /* x is integral */
if(i0<0) i0 += (0x00800000)>>j0;
i0 &= (~i);
}
} else {
if(__builtin_expect(j0==0x80, 0)) return x+x; /* inf or NaN */
else return x; /* x is integral */
}
SET_FLOAT_WORD(x,i0);
return x;
#endif /* ! USE_FLOORF_BUILTIN */
}
#ifndef __floorf
libm_alias_float (__floor, floor)
#endif