mirror of
https://github.com/adtools/clib2.git
synced 2025-12-08 14:59:05 +00:00
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
137 lines
4.5 KiB
C
137 lines
4.5 KiB
C
/*
|
|
* $Id: math_expf.c,v 1.2 2005-05-29 14:45:29 obarthel Exp $
|
|
*
|
|
* :ts=4
|
|
*
|
|
* Portable ISO 'C' (1994) runtime library for the Amiga computer
|
|
* Copyright (c) 2002-2005 by Olaf Barthel <olsen@sourcery.han.de>
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* - Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
*
|
|
* - Neither the name of Olaf Barthel nor the names of contributors
|
|
* may be used to endorse or promote products derived from this
|
|
* software without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
|
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
*
|
|
* PowerPC math library based in part on work by Sun Microsystems
|
|
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
|
|
*
|
|
* Developed at SunPro, a Sun Microsystems, Inc. business.
|
|
* Permission to use, copy, modify, and distribute this
|
|
* software is freely granted, provided that this notice
|
|
* is preserved.
|
|
*
|
|
*
|
|
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
|
|
*/
|
|
|
|
#ifndef _MATH_HEADERS_H
|
|
#include "math_headers.h"
|
|
#endif /* _MATH_HEADERS_H */
|
|
|
|
/****************************************************************************/
|
|
|
|
#if defined(FLOATING_POINT_SUPPORT)
|
|
|
|
/****************************************************************************/
|
|
|
|
static const float
|
|
one = 1.0,
|
|
halF[2] = {0.5,-0.5,},
|
|
huge = 1.0e+30,
|
|
twom100 = 7.8886090522e-31, /* 2**-100=0x0d800000 */
|
|
o_threshold= 8.872283911e+01, /* 0x42b17218 */
|
|
u_threshold= -1.0397208405e+02, /* 0xc2cff1b5 */
|
|
ln2HI[2] ={ 6.9313812256e-01, /* 0x3f317180 */
|
|
-6.9313812256e-01,}, /* 0xbf317180 */
|
|
ln2LO[2] ={ 9.0580006145e-06, /* 0x3717f7d1 */
|
|
-9.0580006145e-06,}, /* 0xb717f7d1 */
|
|
invln2 = 1.4426950216e+00, /* 0x3fb8aa3b */
|
|
P1 = 1.6666667163e-01, /* 0x3e2aaaab */
|
|
P2 = -2.7777778450e-03, /* 0xbb360b61 */
|
|
P3 = 6.6137559770e-05, /* 0x388ab355 */
|
|
P4 = -1.6533901999e-06, /* 0xb5ddea0e */
|
|
P5 = 4.1381369442e-08; /* 0x3331bb4c */
|
|
|
|
float
|
|
expf(float x)
|
|
{
|
|
float y,hi=0.0,lo=0.0,c,t;
|
|
LONG k=0,xsb;
|
|
ULONG hx;
|
|
|
|
GET_FLOAT_WORD(hx,x);
|
|
xsb = (hx>>31)&1; /* sign bit of x */
|
|
hx &= 0x7fffffff; /* high word of |x| */
|
|
|
|
/* filter out non-finite argument */
|
|
if(hx >= 0x42b17218) { /* if |x|>=88.721... */
|
|
if(hx == 0x42b17218) { /* if |x| == 88.7228... */
|
|
if (xsb == 0)
|
|
return FLT_MAX;
|
|
}
|
|
if(hx>0x7f800000)
|
|
return x+x; /* NaN */
|
|
if(hx==0x7f800000)
|
|
return (xsb==0)? x:0.0; /* exp(+-inf)={inf,0} */
|
|
if(x > o_threshold) return huge*huge; /* overflow */
|
|
if(x < u_threshold) return twom100*twom100; /* underflow */
|
|
}
|
|
|
|
/* argument reduction */
|
|
if(hx > 0x3eb17218) { /* if |x| > 0.5 ln2 */
|
|
if(hx < 0x3F851592) { /* and |x| < 1.5 ln2 */
|
|
hi = x-ln2HI[xsb]; lo=ln2LO[xsb]; k = 1-xsb-xsb;
|
|
} else {
|
|
k = invln2*x+halF[xsb];
|
|
t = k;
|
|
hi = x - t*ln2HI[0]; /* t*ln2HI is exact here */
|
|
lo = t*ln2LO[0];
|
|
}
|
|
x = hi - lo;
|
|
}
|
|
else if(hx < 0x31800000) { /* when |x|<2**-28 */
|
|
if(huge+x>one) return one+x;/* trigger inexact */
|
|
}
|
|
else k = 0;
|
|
|
|
/* x is now in primary range */
|
|
t = x*x;
|
|
c = x - t*(P1+t*(P2+t*(P3+t*(P4+t*P5))));
|
|
if(k==0) return one-((x*c)/(c-(float)2.0)-x);
|
|
else y = one-((lo-(x*c)/((float)2.0-c))-hi);
|
|
if(k >= -125) {
|
|
ULONG hy;
|
|
GET_FLOAT_WORD(hy,y);
|
|
SET_FLOAT_WORD(y,hy+(k<<23)); /* add k to y's exponent */
|
|
return y;
|
|
} else {
|
|
ULONG hy;
|
|
GET_FLOAT_WORD(hy,y);
|
|
SET_FLOAT_WORD(y,hy+((k+100)<<23)); /* add k to y's exponent */
|
|
return y*twom100;
|
|
}
|
|
}
|
|
|
|
/****************************************************************************/
|
|
|
|
#endif /* FLOATING_POINT_SUPPORT */
|