113 lines
2.9 KiB
C
113 lines
2.9 KiB
C
/* modf.c - separate floating-point number into integer and fraction parts */
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/* Copyright 1992-1993 Wind River Systems, Inc. */
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/*
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modification history
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--------------------
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01j,19mar95,dvs removed TRON ifdef - no longer supported.
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01i,05feb93,jdi doc changes based on kdl review.
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01h,02dec92,jdi doc tweaks.
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01g,28oct92,jdi documentation cleanup.
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01f,20sep92,smb documentation additions
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01e,10sep92,wmd changed dummy function for i960KB from printf to bcopy.
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01d,04sep92,wmd restored to rev 1b, instead modified mathP.h using _BYTE_ORDER
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conditionals to flip the contents of struct DOUBLE. Added a dummy
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printf() in order to force compiler to compile code correctly for i960kb.
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01c,03sep92,wmd modified modf() for the i960, word order for DOUBLE is reversed.
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01b,25jul92,kdl replaced modf() routine contents with version from floatLib.c;
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deleted isnan(), iszero(), isinf(), _d_type().
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01a,08jul92,smb documentation.
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*/
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/*
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DESCRIPTION
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SEE ALSO: American National Standard X3.159-1989
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NOMANUAL
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*/
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#include "vxWorks.h"
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#include "math.h"
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#include "stddef.h"
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#include "errno.h"
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#include "private/mathP.h"
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/*******************************************************************************
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*
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* modf - separate a floating-point number into integer and fraction parts (ANSI)
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*
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* This routine stores the integer portion of <value>
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* in <pIntPart> and returns the fractional portion.
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* Both parts are double precision and will have the same sign as <value>.
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*
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* INCLUDE FILES: math.h
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*
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* RETURNS: The double-precision fractional portion of <value>.
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*
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* SEE ALSO: frexp(), ldexp()
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*/
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double modf
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(
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double value, /* value to split */
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double *pIntPart /* where integer portion is stored */
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)
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{
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DOUBLE dat;
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FAST int exp;
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FAST double fracPart;
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FAST double intPart;
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int negflag = (value < 0);
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if (negflag)
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value = -value; /* make it positive */
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dat.ddat = value;
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/* Separate the exponent, and change it from biased to 2's comp. */
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exp = ((dat.ldat.l1 & 0x7ff00000) >> 20) - 1023;
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#if CPU==I960KB
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bcopy ((char *)&negflag, (char *)&negflag, 0);
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#endif /* CPU==I960KB - to force gcc960 to compile correct code for the i960kb */
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if (exp <= -1)
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{
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/* If exponent is negative, fracPart == |value|, and intPart == 0. */
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fracPart = value;
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intPart = 0.;
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}
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/* clear the fractional part in dat */
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else if (exp <= 20)
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{
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dat.ldat.l1 &= (-1 << (20 - exp));
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dat.ldat.l2 = 0;
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intPart = dat.ddat;
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fracPart = value - intPart;
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}
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else if (exp <= 52)
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{
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dat.ldat.l2 &= (-1 << (52 - exp));
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intPart = dat.ddat;
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fracPart = value - intPart;
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}
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else
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{
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fracPart = 0.;
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intPart = value;
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}
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*pIntPart = (negflag ? -intPart : intPart);
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return (negflag ? -fracPart : fracPart);
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}
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