44 lines
1.1 KiB
C
44 lines
1.1 KiB
C
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/* s_ilogbf.c -- float version of s_ilogb.c.
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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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#if defined(LIBM_SCCS) && !defined(lint)
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static char rcsid[] = "$NetBSD: s_ilogbf.c,v 1.4 1995/05/10 20:47:31 jtc Exp $";
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#endif
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#include <limits.h>
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#include <math.h>
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#include <math_private.h>
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int __ieee754_ilogbf(float x)
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{
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int32_t hx,ix;
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GET_FLOAT_WORD(hx,x);
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hx &= 0x7fffffff;
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if(hx<0x00800000) {
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if(hx==0)
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return FP_ILOGB0; /* ilogb(0) = FP_ILOGB0 */
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else /* subnormal x */
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for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1;
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return ix;
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}
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else if (hx<0x7f800000) return (hx>>23)-127;
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else if (FP_ILOGBNAN != INT_MAX) {
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/* ISO C99 requires ilogbf(+-Inf) == INT_MAX. */
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if (hx==0x7f800000)
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return INT_MAX;
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}
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return FP_ILOGBNAN;
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}
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