mirror of
https://github.com/KolibriOS/kolibrios.git
synced 2024-12-16 03:42:35 +03:00
846fce0120
git-svn-id: svn://kolibrios.org@4874 a494cfbc-eb01-0410-851d-a64ba20cac60
63 lines
1.5 KiB
C
63 lines
1.5 KiB
C
/* 2009 for Newlib: Sun's sf_ilogb.c converted to be sf_logb.c. */
|
|
/*
|
|
* ====================================================
|
|
* 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.
|
|
* ====================================================
|
|
*/
|
|
|
|
/* float logb(float x)
|
|
* return the binary exponent of non-zero x
|
|
* logbf(0) = -inf, raise divide-by-zero floating point exception
|
|
* logbf(+inf|-inf) = +inf (no signal is raised)
|
|
* logbf(NaN) = NaN (no signal is raised)
|
|
* Per C99 recommendation, a NaN argument is returned unchanged.
|
|
*/
|
|
|
|
#include "fdlibm.h"
|
|
|
|
float
|
|
#ifdef __STDC__
|
|
logbf(float x)
|
|
#else
|
|
logbf(x)
|
|
float x;
|
|
#endif
|
|
{
|
|
__int32_t hx,ix;
|
|
|
|
GET_FLOAT_WORD(hx,x);
|
|
hx &= 0x7fffffff;
|
|
if(FLT_UWORD_IS_ZERO(hx)) {
|
|
float xx;
|
|
/* arg==0: return -inf and raise divide-by-zero exception */
|
|
SET_FLOAT_WORD(xx,hx); /* +0.0 */
|
|
return -1./xx; /* logbf(0) = -inf */
|
|
}
|
|
if(FLT_UWORD_IS_SUBNORMAL(hx)) {
|
|
for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1;
|
|
return (float) ix;
|
|
}
|
|
else if (FLT_UWORD_IS_INFINITE(hx)) return HUGE_VALF; /* x==+|-inf */
|
|
else if (FLT_UWORD_IS_NAN(hx)) return x;
|
|
else return (float) ((hx>>23)-127);
|
|
}
|
|
|
|
#ifdef _DOUBLE_IS_32BITS
|
|
|
|
#ifdef __STDC__
|
|
double logb(double x)
|
|
#else
|
|
double logb(x)
|
|
double x;
|
|
#endif
|
|
{
|
|
return (double) logbf((float) x);
|
|
}
|
|
|
|
#endif /* defined(_DOUBLE_IS_32BITS) */
|