49 lines
1.0 KiB
C
49 lines
1.0 KiB
C
/* sf_logb.c -- float version of s_logb.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.
|
|
* ====================================================
|
|
*/
|
|
|
|
#include "fdlibm.h"
|
|
|
|
#ifdef __STDC__
|
|
float logbf(float x)
|
|
#else
|
|
float logbf(x)
|
|
float x;
|
|
#endif
|
|
{
|
|
__int32_t ix;
|
|
GET_FLOAT_WORD(ix,x);
|
|
ix &= 0x7fffffff; /* high |x| */
|
|
if(ix==0) return (float)-1.0/fabsf(x);
|
|
if(ix>=0x7f800000) return x*x;
|
|
if((ix>>=23)==0) /* IEEE 754 logb */
|
|
return -126.0;
|
|
else
|
|
return (float) (ix-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) */
|