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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
138 lines
4.4 KiB
C
138 lines
4.4 KiB
C
/*
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* $Id: math_log1pf.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
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ln2_hi = 6.9313812256e-01, /* 0x3f317180 */
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ln2_lo = 9.0580006145e-06, /* 0x3717f7d1 */
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two25 = 3.355443200e+07, /* 0x4c000000 */
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Lp1 = 6.6666668653e-01, /* 3F2AAAAB */
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Lp2 = 4.0000000596e-01, /* 3ECCCCCD */
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Lp3 = 2.8571429849e-01, /* 3E924925 */
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Lp4 = 2.2222198546e-01, /* 3E638E29 */
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Lp5 = 1.8183572590e-01, /* 3E3A3325 */
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Lp6 = 1.5313838422e-01, /* 3E1CD04F */
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Lp7 = 1.4798198640e-01; /* 3E178897 */
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static const float zero = 0.0;
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float
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log1pf(float x)
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{
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float hfsq,f=0.0,c=0.0,s,z,R;
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volatile float u; /* so GCC doesn't optimize it away */
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LONG k,hx,hu=0.0,ax;
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GET_FLOAT_WORD(hx,x);
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ax = hx&0x7fffffff;
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k = 1;
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if (hx < 0x3ed413d7) { /* x < 0.41422 */
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if(ax>=0x3f800000) /* x <= -1.0 */
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return logf(1+x); /* log1p(x<=-1) */
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if(ax<0x31000000) { /* |x| < 2**-29 */
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if(two25+x>zero /* raise inexact */
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&&ax<0x24800000) /* |x| < 2**-54 */
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return x;
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else
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return x - x*x*(float)0.5;
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}
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if(hx>0||hx<=((LONG)0xbe95f61fU)) {
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k=0;f=x;hu=1;} /* -0.2929<x<0.41422 */
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}
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if (hx >= 0x7f800000) return x+x;
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if(k!=0) {
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if(hx<0x5a000000) {
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u = (float)1.0+x;
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GET_FLOAT_WORD(hu,u);
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k = (hu>>23)-127;
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/* correction term */
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c = (k>0)? (float)1.0-(u-x):x-(u-(float)1.0);
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c /= u;
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} else {
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u = x;
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GET_FLOAT_WORD(hu,u);
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k = (hu>>23)-127;
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c = 0;
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}
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hu &= 0x007fffff;
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if(hu<0x3504f7) {
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SET_FLOAT_WORD(u,hu|0x3f800000);/* normalize u */
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} else {
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k += 1;
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SET_FLOAT_WORD(u,hu|0x3f000000); /* normalize u/2 */
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hu = (0x00800000-hu)>>2;
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}
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f = u-(float)1.0;
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}
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hfsq=(float)0.5*f*f;
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if(hu==0) { /* |f| < 2**-20 */
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if(f==zero) { if(k==0) return zero;
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else {c += k*ln2_lo; return k*ln2_hi+c;}
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}
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R = hfsq*((float)1.0-(float)0.66666666666666666*f);
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if(k==0) return f-R; else
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return k*ln2_hi-((R-(k*ln2_lo+c))-f);
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}
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s = f/((float)2.0+f);
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z = s*s;
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R = z*(Lp1+z*(Lp2+z*(Lp3+z*(Lp4+z*(Lp5+z*(Lp6+z*Lp7))))));
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if(k==0) return f-(hfsq-s*(hfsq+R)); else
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return k*ln2_hi-((hfsq-(s*(hfsq+R)+(k*ln2_lo+c)))-f);
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}
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/****************************************************************************/
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#endif /* FLOATING_POINT_SUPPORT */
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