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121 lines
3.5 KiB
121 lines
3.5 KiB
/* This file has been modified by Hongjiu Lu (Feb 1992).
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*/
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/* This file may have been modified by DJ Delorie (Jan 1991). If so,
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** these modifications are Coyright (C) 1991 DJ Delorie, 24 Kirsten Ave,
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** Rochester NH, 03867-2954, USA.
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*/
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/*-
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Sean Eric Fagan
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*
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* Redistribution and use in source and binary forms are permitted
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* provided that: (1) source distributions retain this entire copyright
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* notice and comment, and (2) distributions including binaries display
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* the following acknowledgement: ``This product includes software
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* developed by the University of California, Berkeley and its contributors''
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* in the documentation or other materials provided with the distribution
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* and in all advertising materials mentioning features or use of this
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* software. Neither the name of the University nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#ifndef SOFT_387
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)modf.c 5.1 (Berkeley) 4/23/90";
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#endif /* LIBC_SCCS and not lint */
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/*
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* modf(value, iptr): return fractional part of value, and stores the
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* integral part into iptr (a pointer to double).
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*
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* Written by Sean Eric Fagan (sef@kithrup.COM)
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* Sun Mar 11 20:27:30 PST 1990
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*/
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/* With CHOP mode on, frndint behaves as TRUNC does. Useful. */
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double
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modf(double value, double *iptr)
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{
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double temp;
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volatile short i87flag, i87temp;
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__asm ("fnstcw %0" : "=m" (i87flag) : );
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i87temp = i87flag | 0xc00 ; /* turn on chop mode [truncation] */
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__asm ("fldcw %0" : : "m" (i87temp));
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#ifdef PRE_GCC_2
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__asm ("frndint" : "=t" (temp) : "0" (value)); /* temp = int of value */
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#else
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__asm ("frndint" : "=f" (temp) : "0" (value)); /* temp = int of value */
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#endif
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__asm ("fldcw %0" : : "m" (i87flag));
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*iptr = temp;
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return (value - temp);
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}
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#else
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#include "soft.h"
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#define shiftleft(dp,n) { /* n = 0 to 32 */ \
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dp->mant1 = ((dp->mant1 << (n)) + (dp->mant2 >> (32-(n)))) \
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& 0x0FFFFF; dp->mant2 <<= (n); dp->exp -= (n); }
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/* Returns fractional part of d, stores integer part in *integ
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*/
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double modf(double d, double *integ)
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{
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struct bitdouble *dp = (struct bitdouble *)&d;
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struct bitdouble *ip = (struct bitdouble *)integ;
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int e = dp->exp - BIAS;
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if (e < 0) { /* no integer part */
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*integ = 0;
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return d;
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}
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/* compute integer: clear fractional part where necessary
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*/
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*integ = d;
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if (e <= 20) {
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ip->mant1 &= (-1L << (20-e)); /* split in mant1... */
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ip->mant2 = 0;
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}
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else
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if (e <= 52)
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ip->mant2 &= (-1L << (52-e)); /* split in mant2 */
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else return 0; /* no fractional part */
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/* compute fractional part: shift left over integer part
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*/
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if (e)
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if (e <= 32)
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shiftleft(dp,e)
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else {
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dp->mant1 = (dp->mant2 << (e-32)) & 0x0FFFFF;
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dp->mant2 = 0;
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dp->exp -= e;
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}
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/* adjust fractional part shifting left...
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*/
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if (dp->mant1==0 && dp->mant2==0) /* fraction is zero */
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return 0;
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while (!(dp->mant1 & 0x080000)) /* stack to the left */
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shiftleft(dp,1);
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shiftleft(dp,1); /* lose 'invisible bit' */
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return d;
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}
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#endif
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