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git-svn-id: file:///Users/olsen/Code/migration-svn-zu-git/logical-line-staging/clib2/trunk@15079 87f5fb63-7c3d-0410-a384-fd976d0f7a62
137 lines
4.2 KiB
C
137 lines
4.2 KiB
C
/*
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* $Id: math_modff.c,v 1.3 2006-01-08 12:04:23 obarthel Exp $
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*
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* :ts=4
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*
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* Portable ISO 'C' (1994) runtime library for the Amiga computer
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* Copyright (c) 2002-2006 by Olaf Barthel <olsen (at) sourcery.han.de>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* - Neither the name of Olaf Barthel nor the names of contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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*
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* PowerPC math library based in part on work by Sun Microsystems
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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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* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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*/
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#ifndef _MATH_HEADERS_H
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#include "math_headers.h"
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#endif /* _MATH_HEADERS_H */
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/****************************************************************************/
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#if defined(FLOATING_POINT_SUPPORT)
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/****************************************************************************/
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static const float one = 1.0, Zero[] = {0.0, -0.0,};
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float
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fmodf(float x, float y)
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{
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LONG n,hx,hy,hz,ix,iy,sx,i;
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GET_FLOAT_WORD(hx,x);
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GET_FLOAT_WORD(hy,y);
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sx = hx&0x80000000U; /* sign of x */
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hx ^=sx; /* |x| */
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hy &= 0x7fffffff; /* |y| */
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/* purge off exception values */
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if(hy==0||(hx>=0x7f800000)|| /* y=0,or x not finite */
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(hy>0x7f800000)) /* or y is NaN */
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return (x*y)/(x*y);
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if(hx<hy) return x; /* |x|<|y| return x */
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if(hx==hy)
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return Zero[(ULONG)sx>>31]; /* |x|=|y| return x*0*/
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/* determine ix = ilogb(x) */
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if(hx<0x00800000) { /* subnormal x */
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for (ix = -126,i=(hx<<8); i>0; i<<=1) ix -=1;
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} else ix = (hx>>23)-127;
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/* determine iy = ilogb(y) */
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if(hy<0x00800000) { /* subnormal y */
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for (iy = -126,i=(hy<<8); i>=0; i<<=1) iy -=1;
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} else iy = (hy>>23)-127;
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/* set up {hx,lx}, {hy,ly} and align y to x */
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if(ix >= -126)
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hx = 0x00800000|(0x007fffff&hx);
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else { /* subnormal x, shift x to normal */
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n = -126-ix;
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hx = hx<<n;
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}
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if(iy >= -126)
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hy = 0x00800000|(0x007fffff&hy);
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else { /* subnormal y, shift y to normal */
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n = -126-iy;
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hy = hy<<n;
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}
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/* fix point fmod */
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n = ix - iy;
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while(n--) {
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hz=hx-hy;
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if(hz<0){hx = hx+hx;}
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else {
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if(hz==0) /* return sign(x)*0 */
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return Zero[(ULONG)sx>>31];
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hx = hz+hz;
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}
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}
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hz=hx-hy;
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if(hz>=0) {hx=hz;}
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/* convert back to floating value and restore the sign */
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if(hx==0) /* return sign(x)*0 */
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return Zero[(ULONG)sx>>31];
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while(hx<0x00800000) { /* normalize x */
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hx = hx+hx;
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iy -= 1;
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}
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if(iy>= -126) { /* normalize output */
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hx = ((hx-0x00800000)|((iy+127)<<23));
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SET_FLOAT_WORD(x,hx|sx);
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} else { /* subnormal output */
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n = -126 - iy;
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hx >>= n;
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SET_FLOAT_WORD(x,hx|sx);
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x *= one; /* create necessary signal */
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}
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return x; /* exact output */
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}
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/****************************************************************************/
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#endif /* FLOATING_POINT_SUPPORT */
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