125 lines
2.7 KiB
C
125 lines
2.7 KiB
C
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/* @(#)z_isnan.c 1.0 98/08/13 */
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/*
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FUNCTION
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<<isnan>>, <<isnanf>>, <<isinf>>, <<isinff>>, <<finite>>, <<finitef>>---test
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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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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
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*
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* Input:
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* x - pointer to a floating-point value
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*
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* Output:
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* An integer that indicates if the number is NaN.
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*
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* Description:
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* This routine returns an integer that indicates if the number
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* passed in is NaN (1) or is finite (0).
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*
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*****************************************************************/
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#include "fdlibm.h"
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#include "zmath.h"
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#ifndef _DOUBLE_IS_32BITS
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int isnan (double x)
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{
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__uint32_t lx, hx;
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int exp;
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EXTRACT_WORDS (hx, lx, x);
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exp = (hx & 0x7ff00000) >> 20;
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if ((exp == 0x7ff) && (hx & 0xf0000 || lx))
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return (1);
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else
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return (0);
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}
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#endif /* _DOUBLE_IS_32BITS */
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