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3c220c3939
- Ported acosf(), asinf(), atan2f(), atanf(), ceilf(), expf(), floorf(), fmodf(), frexpf(), ldexpf(), log10f(), logbf(), logf(), modff(), powf(), sqrtf(), scalbn() and scalbnf() for C99. - Ported cbrt(), cbrtf(), erf(), erff(), erfc(), erfcf(), expm1(), expm1f(), ilogb(), ilogbf(), log1p() and log1pf() for C99. git-svn-id: file:///Users/olsen/Code/migration-svn-zu-git/logical-line-staging/clib2/trunk@14963 87f5fb63-7c3d-0410-a384-fd976d0f7a62
127 lines
3.6 KiB
C
127 lines
3.6 KiB
C
/*
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* $Id: math_sqrtf.c,v 1.2 2005-05-29 14:45:32 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) 2002-2005 by Olaf Barthel <olsen@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, tiny=1.0e-30;
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float
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sqrtf(float x)
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{
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volatile float z; /* to prevent GCC from optimizing it away */
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LONG sign = (LONG)0x80000000U;
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ULONG r;
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LONG ix,s,q,m,t,i;
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GET_FLOAT_WORD(ix,x);
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/* take care of Inf and NaN */
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if((ix&0x7f800000)==0x7f800000) {
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return x*x+x; /* sqrt(NaN)=NaN, sqrt(+inf)=+inf
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sqrt(-inf)=sNaN */
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}
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/* take care of zero */
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if(ix<=0) {
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if((ix&(~sign))==0) return x;/* sqrt(+-0) = +-0 */
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else if(ix<0)
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return (x-x)/(x-x); /* sqrt(-ve) = sNaN */
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}
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/* normalize x */
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m = (ix>>23);
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if(m==0) { /* subnormal x */
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for(i=0;(ix&0x00800000)==0;i++) ix<<=1;
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m -= i-1;
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}
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m -= 127; /* unbias exponent */
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ix = (ix&0x007fffff)|0x00800000;
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if(m&1) /* odd m, double x to make it even */
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ix += ix;
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m >>= 1; /* m = [m/2] */
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/* generate sqrt(x) bit by bit */
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ix += ix;
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q = s = 0; /* q = sqrt(x) */
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r = 0x01000000; /* r = moving bit from right to left */
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while(r!=0) {
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t = s+r;
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if(t<=ix) {
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s = t+r;
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ix -= t;
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q += r;
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}
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ix += ix;
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r>>=1;
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}
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/* use floating add to find out rounding direction */
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if(ix!=0) {
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z = one-tiny; /* trigger inexact flag */
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if (z>=one) {
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z = one+tiny;
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if (z>one)
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q += 2;
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else
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q += (q&1);
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}
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}
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ix = (q>>1)+0x3f000000;
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ix += (m <<23);
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SET_FLOAT_WORD(z,ix);
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return z;
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}
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/****************************************************************************/
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#endif /* FLOATING_POINT_SUPPORT */
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