author | Jan Vrany <jan.vrany@fit.cvut.cz> |
Tue, 11 Jun 2019 22:03:11 +0100 | |
changeset 3914 | 35aa88fa58c1 |
parent 2380 | 9195eccdcbd9 |
permissions | -rw-r--r-- |
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/* @(#)s_ilogb.c 1.3 95/01/18 */ |
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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 SunSoft, 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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|
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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) = 0x80000001 |
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* ilogb(inf/NaN) = 0x7fffffff (no signal is raised) |
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*/ |
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|
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#include "fdlibm.h" |
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|
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#ifdef __STDC__ |
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int ilogb(double x) |
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#else |
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int ilogb(x) |
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double x; |
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#endif |
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{ |
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int hx,lx,ix; |
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hx = (__HI(x))&0x7fffffff; /* high word of x */ |
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if(hx<0x00100000) { |
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lx = __LO(x); |
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if((hx|lx)==0) |
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return 0x80000001; /* ilogb(0) = 0x80000001 */ |
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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 return 0x7fffffff; |
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} |