451a8eb09a
* libm/common/s_ilogb.c: Adjust documentation to reflect new returns
(see next items) and that ilogb() and ilogbf() are C99/POSIX.
* libm/common/s_ilogb.c (ilogb): Use C99/POSIX FP_ILOGB0 and
FP_ILOGBNAN returns for 0 and NAN arguments, respectively, instead of
the prior -INT_MAX and INT_MAX. The FP_ILOGBx defines in math.h
presently match the prior hard-codes, so no functional change is
actually introduced. (Not at this time, nor planned, but the values
are permitted to be different, so subsequent edits of math.h could
possibly cause a functional change.)
* libm/common/sf_ilogb.c (ilogbf): Ditto.
56 lines
1.2 KiB
C
56 lines
1.2 KiB
C
/* sf_ilogb.c -- float version of s_ilogb.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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#include <limits.h>
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#include "fdlibm.h"
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#ifdef __STDC__
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int ilogbf(float x)
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#else
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int ilogbf(x)
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float x;
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#endif
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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(FLT_UWORD_IS_ZERO(hx))
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return FP_ILOGB0; /* ilogb(0) = special case error */
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if(FLT_UWORD_IS_SUBNORMAL(hx)) {
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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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#if FP_ILOGBNAN != INT_MAX
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else if (FLT_UWORD_IS_NAN(hx)) return FP_ILOGBNAN; /* NAN */
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#endif
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else if (!FLT_UWORD_IS_FINITE(hx)) return INT_MAX;
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else return (hx>>23)-127;
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}
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#ifdef _DOUBLE_IS_32BITS
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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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return ilogbf((float) x);
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}
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#endif /* defined(_DOUBLE_IS_32BITS) */
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