136 lines
3.0 KiB
C
136 lines
3.0 KiB
C
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/* @(#)s_isnan.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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/*
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FUNCTION
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<<isnan>>, <<isnanf>>, <<isinf>>, <<isinff>>, <<finite>>, <<finitef>>---test for exceptional numbers
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INDEX
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isnan
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INDEX
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isinf
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INDEX
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finite
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INDEX
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isnanf
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INDEX
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isinff
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INDEX
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finitef
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ANSI_SYNOPSIS
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#include <ieeefp.h>
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int isnan(double <[arg]>);
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int isinf(double <[arg]>);
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int finite(double <[arg]>);
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int isnanf(float <[arg]>);
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int isinff(float <[arg]>);
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int finitef(float <[arg]>);
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TRAD_SYNOPSIS
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#include <ieeefp.h>
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int isnan(<[arg]>)
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double <[arg]>;
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int isinf(<[arg]>)
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double <[arg]>;
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int finite(<[arg]>);
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double <[arg]>;
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int isnanf(<[arg]>);
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float <[arg]>;
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int isinff(<[arg]>);
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float <[arg]>;
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int finitef(<[arg]>);
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float <[arg]>;
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DESCRIPTION
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These functions provide information on the floating-point
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argument supplied.
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There are five major number formats:
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o+
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o zero
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A number which contains all zero bits.
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o subnormal
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A number with a zero exponent but a nonzero fraction.
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o normal
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A number with an exponent and a fraction.
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o infinity
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A number with an all 1's exponent and a zero fraction.
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o NAN
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A number with an all 1's exponent and a nonzero fraction.
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o-
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<<isnan>> returns 1 if the argument is a nan. <<isinf>>
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returns 1 if the argument is infinity. <<finite>> returns 1 if the
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argument is zero, subnormal or normal.
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The <<isnanf>>, <<isinff>> and <<finitef>> functions perform the same
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operations as their <<isnan>>, <<isinf>> and <<finite>>
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counterparts, but on single-precision floating-point numbers.
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It should be noted that the C99 standard dictates that <<isnan>>
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and <<isinf>> are macros that operate on multiple types of
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floating-point. The SUSv2 standard declares <<isnan>> as
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a function taking double. Newlib has decided to declare
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them both as macros in math.h and as functions in ieeefp.h.
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QUICKREF
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isnan - pure
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QUICKREF
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isinf - pure
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QUICKREF
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finite - pure
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QUICKREF
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isnan - pure
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QUICKREF
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isinf - pure
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QUICKREF
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finite - pure
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*/
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/*
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* isnan(x) returns 1 is x is nan, else 0;
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* no branching!
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*
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* The C99 standard dictates that isnan is a macro taking
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* multiple floating-point types while the SUSv2 standard
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* notes it is a function taking a double argument. Newlib
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* has chosen to implement it as a macro in <math.h> and
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* declare it as a function in <ieeefp.h>.
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*/
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#include "fdlibm.h"
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#include <ieeefp.h>
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#ifndef _DOUBLE_IS_32BITS
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#ifdef __STDC__
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int isnan(double x)
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#else
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int isnan(x)
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double x;
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#endif
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{
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__int32_t hx,lx;
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EXTRACT_WORDS(hx,lx,x);
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hx &= 0x7fffffff;
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hx |= (__uint32_t)(lx|(-lx))>>31;
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hx = 0x7ff00000 - hx;
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return (int)(((__uint32_t)(hx))>>31);
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}
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#endif /* _DOUBLE_IS_32BITS */
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