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git-svn-id: file:///Users/olsen/Code/migration-svn-zu-git/logical-line-staging/clib2/trunk@14685 87f5fb63-7c3d-0410-a384-fd976d0f7a62
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Olaf Barthel
252
library/math_exp.c
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252
library/math_exp.c
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/*
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* $Id: math_exp.c,v 1.1.1.1 2004-07-26 16:30:41 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) 2002-2004 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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#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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#if defined(IEEE_FLOATING_POINT_SUPPORT)
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/****************************************************************************/
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#if defined(__GNUC__)
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/****************************************************************************/
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#if defined(SMALL_DATA)
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#define A4(x) "a4@(" #x ":W)"
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#elif defined(SMALL_DATA32)
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#define A4(x) "a4@(" #x ":L)"
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#else
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#define A4(x) #x
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#endif /* SMALL_DATA */
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/****************************************************************************/
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extern double __exp(double x);
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/****************************************************************************/
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asm("
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.text
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.even
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.globl _MathIeeeDoubTransBase
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.globl ___exp
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___exp:
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movel a6,sp@-
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movel "A4(_MathIeeeDoubTransBase)",a6
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moveml sp@(8),d0/d1
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jsr a6@(-78:W)
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movel sp@+,a6
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rts
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");
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/****************************************************************************/
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#else
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/****************************************************************************/
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INLINE static const double
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__exp(double x)
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{
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double result;
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result = IEEEDPExp(x);
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return(result);
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}
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/****************************************************************************/
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#endif /* __GNUC__ */
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/****************************************************************************/
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#endif /* IEEE_FLOATING_POINT_SUPPORT */
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/****************************************************************************/
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#if defined(M68881_FLOATING_POINT_SUPPORT)
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INLINE static const double
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__exp(double x)
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{
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double result;
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__asm ("fetox%.x %1,%0"
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: "=f" (result)
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: "f" (x));
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return(result);
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}
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#endif /* M68881_FLOATING_POINT_SUPPORT */
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/****************************************************************************/
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#if defined(PPC_FLOATING_POINT_SUPPORT)
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static const double
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one = 1.0,
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halF[2] = {0.5,-0.5,},
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huge = 1.0e+300,
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twom1000= 9.33263618503218878990e-302, /* 2**-1000=0x01700000,0*/
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o_threshold= 7.09782712893383973096e+02, /* 0x40862E42, 0xFEFA39EF */
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u_threshold= -7.45133219101941108420e+02, /* 0xc0874910, 0xD52D3051 */
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ln2HI[2] ={ 6.93147180369123816490e-01, /* 0x3fe62e42, 0xfee00000 */
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-6.93147180369123816490e-01,}, /* 0xbfe62e42, 0xfee00000 */
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ln2LO[2] ={ 1.90821492927058770002e-10, /* 0x3dea39ef, 0x35793c76 */
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-1.90821492927058770002e-10,}, /* 0xbdea39ef, 0x35793c76 */
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invln2 = 1.44269504088896338700e+00, /* 0x3ff71547, 0x652b82fe */
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P1 = 1.66666666666666019037e-01, /* 0x3FC55555, 0x5555553E */
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P2 = -2.77777777770155933842e-03, /* 0xBF66C16C, 0x16BEBD93 */
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P3 = 6.61375632143793436117e-05, /* 0x3F11566A, 0xAF25DE2C */
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P4 = -1.65339022054652515390e-06, /* 0xBEBBBD41, 0xC5D26BF1 */
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P5 = 4.13813679705723846039e-08; /* 0x3E663769, 0x72BEA4D0 */
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INLINE static const double
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__exp(double x)
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{
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double y,hi,lo,c,t;
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int k,xsb;
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unsigned int hx;
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GET_HIGH_WORD(hx,x);
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xsb = (hx>>31)&1; /* sign bit of x */
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hx &= 0x7fffffff; /* high word of |x| */
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/* filter out non-finite argument */
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if(hx >= 0x40862E42)
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{ /* if |x|>=709.78... */
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if(hx>=0x7ff00000)
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{
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unsigned int lx;
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GET_LOW_WORD(lx,x);
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if(((hx&0xfffff)|lx)!=0)
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return x+x; /* NaN */
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else
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return (xsb==0)? x:0.0; /* exp(+-inf)={inf,0} */
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}
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if(x > o_threshold)
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return huge*huge; /* overflow */
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if(x < u_threshold)
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return twom1000*twom1000; /* underflow */
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}
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/* argument reduction */
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if(hx > 0x3fd62e42)
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{ /* if |x| > 0.5 ln2 */
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if(hx < 0x3FF0A2B2)
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{ /* and |x| < 1.5 ln2 */
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hi = x-ln2HI[xsb]; lo=ln2LO[xsb]; k = 1-xsb-xsb;
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}
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else
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{
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k = invln2*x+halF[xsb];
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t = k;
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hi = x - t*ln2HI[0]; /* t*ln2HI is exact here */
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lo = t*ln2LO[0];
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}
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x = hi - lo;
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}
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else if(hx < 0x3e300000)
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{ /* when |x|<2**-28 */
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if(huge+x>one)
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return one+x; /* trigger inexact */
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}
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else
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k = 0;
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/* x is now in primary range */
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t = x*x;
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c = x - t*(P1+t*(P2+t*(P3+t*(P4+t*P5))));
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if(k==0)
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return one-((x*c)/(c-2.0)-x);
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else
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y = one-((lo-(x*c)/(2.0-c))-hi);
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if(k >= -1021)
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{
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unsigned int hy;
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GET_HIGH_WORD(hy,y);
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SET_HIGH_WORD(y,hy+(k<<20)); /* add k to y's exponent */
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return y;
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}
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else
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{
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unsigned int hy;
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GET_HIGH_WORD(hy,y);
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SET_HIGH_WORD(y,hy+((k+1000)<<20)); /* add k to y's exponent */
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return y*twom1000;
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}
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}
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#endif /* PPC_FLOATING_POINT_SUPPORT */
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/****************************************************************************/
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double
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exp(double x)
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{
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double result;
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result = __exp(x);
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return(result);
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}
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/****************************************************************************/
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#endif /* FLOATING_POINT_SUPPORT */
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