author | William Roberts <williamr@symbian.org> |
Thu, 22 Jul 2010 16:48:56 +0100 | |
branch | GCC_SURGE |
changeset 45 | 4b03adbd26ca |
parent 0 | e4d67989cc36 |
permissions | -rw-r--r-- |
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/*-------------------------------------------------------------------- |
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*© Portions copyright (c) 2006 Nokia Corporation. All rights reserved. |
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*-------------------------------------------------------------------- |
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*/ |
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/* @(#)s_ilogb.c 5.1 93/09/24 */ |
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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 __SYMBIAN32__ |
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#ifndef lint |
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static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_ilogb.c,v 1.9 2004/10/09 17:14:28 stefanf Exp $"; |
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#endif |
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#endif //__SYMBIAN32__ |
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|
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/* ilogb(double x) |
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* return the binary exponent of non-zero x |
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* ilogb(0) = FP_ILOGB0 |
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* ilogb(NaN) = FP_ILOGBNAN (no signal is raised) |
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* ilogb(inf) = INT_MAX (no signal is raised) |
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*/ |
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|
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#include <limits.h> |
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|
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#include <math.h> |
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#include "math_private.h" |
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EXPORT_C int ilogb(double x) |
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{ |
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int32_t hx,lx,ix; |
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EXTRACT_WORDS(hx,lx,x); |
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hx &= 0x7fffffff; |
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if(hx<0x00100000) { |
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if((hx|lx)==0) |
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return FP_ILOGB0; |
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else /* subnormal x */ |
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if(hx==0) { |
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for (ix = -1043; lx>0; lx<<=1) ix -=1; |
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} else { |
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for (ix = -1022,hx<<=11; hx>0; hx<<=1) ix -=1; |
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} |
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return ix; |
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} |
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else if (hx<0x7ff00000) return (hx>>20)-1023; |
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else if (hx>0x7ff00000 || lx!=0) return FP_ILOGBNAN; |
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else return INT_MAX; |
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} |