42 lines
1.1 KiB
C
42 lines
1.1 KiB
C
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/* s_logbf.c -- float version of s_logb.c.
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* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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*/
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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#ifndef lint
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static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_logbf.c,v 1.8 2005/12/03 11:57:19 bde Exp $";
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#endif
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#include "math.h"
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#include "math_private.h"
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static const float
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two25 = 3.355443200e+07; /* 0x4c000000 */
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float
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logbf(float x)
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{
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int32_t ix;
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GET_FLOAT_WORD(ix,x);
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ix &= 0x7fffffff; /* high |x| */
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if(ix==0) return (float)-1.0/fabsf(x);
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if(ix>=0x7f800000) return x*x;
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if(ix<0x00800000) {
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x *= two25; /* convert subnormal x to normal */
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GET_FLOAT_WORD(ix,x);
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ix &= 0x7fffffff;
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return (float) ((ix>>23)-127-25);
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} else
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return (float) ((ix>>23)-127);
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}
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