src/math/s_logbf.c


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/* s_logbf.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 <math.h>
#include "math_private.h"

float
logbf(float x)
{
        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);
}