newlib-cygwin/newlib/libm/math/ef_exp.c

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2000-02-18 03:39:52 +08:00
/* ef_exp.c -- float version of e_exp.c.
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
*/
/*
* ====================================================
* 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.
* ====================================================
*/
#include "fdlibm.h"
#ifdef __v810__
#define const
#endif
#ifdef __STDC__
static const float
#else
static float
#endif
one = 1.0,
halF[2] = {0.5,-0.5,},
huge = 1.0e+30,
twom100 = 7.8886090522e-31, /* 2**-100=0x0d800000 */
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 */
#ifdef __STDC__
float __ieee754_expf(float x) /* default IEEE double exp */
#else
float __ieee754_expf(x) /* default IEEE double exp */
float x;
#endif
{
float y,hi,lo,c,t;
Throughout, run newlib with -Wall -Werror option and fix bugs and compiler warnings found this way. * libc/stdio/freopen.c (_freopen_r): Fix bug setting _flags. * libc/include/stdio.h (_rename): Define when building newlib. * libc/include/sys/signal.h (_kill): Ditto. * libc/include/sys/stat.h (_mkdir): Ditto. * libc/include/sys/time.h (_gettimeofday): Ditto. * libc/include/sys/times.h (_times): Ditto. * libc/include/sys/wait.h (_wait): Ditto. * libc/locale/lmessages.c (empty): Don't define for Cygwin. * libc/locale/lmonetary.c (cnv): Ditto. * libc/locale/nl_langinfo.c (nl_langinfo): Ditto for variable s. * libc/posix/collate.c: Throughout cast to avoid compiler warning. * libc/posix/engine.c (matcher): Initialize dp to avoid compiler warning. * libc/posix/glob.c: Disable on Cygwin. Explain why. * libc/posix/regcomp.c: Fix "uninitialized" compiler warnings. (dissect): Deliberately silence gcc compiler warning. Add comment to explain why. * libc/posix/wordexp.c (wordexp): Remove num_bytes variable since result is never used. * libc/posix/popen.c (popen): Ditto for variable last. * libc/reent/mkdirr.c: Include sys/stat.h. * libc/reent/renamer.c: Include stdio.h. * libc/search/hash.c: Throughout use underscored variants of the stat function family. (init_hash): Add missing definition for the __USE_INTERNAL_STAT64 case. * libc/search/hash_bigkey.c (__big_insert): Add parenthesis to avoid compiler warning. * libc/search/hash_page.c (overflow_page): Initalize freep to NULL to avoid compiler warning. * libc/stdio/asiprintf.c (_asiprintf_r): Cast unsigned char * to char * to avoid compiler warning. (asiprintf): Ditto. * libc/stdio/asprintf.c (_asprintf_r): Ditto. (asprintf): Ditto. * libc/stdio/vasiprintf.c (_vasiprintf_r): Ditto. * libc/stdio/vasprintf.c (_vasprintf_r): Ditto. * libc/stdio/mktemp.c (_gettemp): Cast to unsigned char in call to isdigit to avoid compiler warning. * libc/stdio/vfprintf.c (_VFPRINTF_R): Initialize variables used for grouping to avoid compiler warning. Only define and set nseps and nrepeats if they are really used. * libc/stdio/vfwprintf.c (_VFWPRINTF_R): Ditto. Only define state if it is really used. * libc/stdio/vfscanf.c (u_char): Revert to be defined as unsigned char. (__SVFSCANF_R): Cast fmt in call to __mbtowc. * libc/stdlib/mbtowc_r.c (JIS_state_table): Disable when building Cygwin. (JIS_action_table): Ditto. * libc/stdlib/wctomb_r.c (__utf8_wctomb): Add parenthesis to avoid compiler warning. * libc/string/strcasestr.c: Deliberately silence gcc compiler warning. Add comment to explain why. * libc/time/strptime.c (strptime): Cast to unsigned char in calls to isspace to avoid compiler warning. * libm/math/e_atan2.c (__ieee754_atan2): Add parenthesis to avoid compiler warning. * libm/math/e_exp.c (__ieee754_exp): Initialize k to 0 to avoid compiler warning. Drop setting it to 0 later. * libm/math/ef_exp.c (__ieee754_expf): Ditto. * libm/math/e_pow.c (__ieee754_pow): Add braces to avoid compiler warning. * libm/math/ef_pow.c (__ieee754_powf): Ditto. * libm/math/er_lgamma.c (__ieee754_lgamma_r): Initialize nadj to 0 to avoid compiler warning. * libm/math/erf_lgamma.c (__ieee754_lgammaf_r): Ditto. * libm/math/e_rem_pio2.c (__ieee754_rem_pio2): Ditto for variable z. * libm/common/sf_round.c (roundf): Remove signbit variable since result is never used.
2012-08-08 19:04:18 +08:00
__int32_t k = 0,xsb,sx;
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__uint32_t hx;
GET_FLOAT_WORD(sx,x);
xsb = (sx>>31)&1; /* sign bit of x */
hx = sx & 0x7fffffff; /* high word of |x| */
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/* filter out non-finite argument */
if(FLT_UWORD_IS_NAN(hx))
return x+x; /* NaN */
if(FLT_UWORD_IS_INFINITE(hx))
return (xsb==0)? x:0.0; /* exp(+-inf)={inf,0} */
if(sx > FLT_UWORD_LOG_MAX)
return huge*huge; /* overflow */
if(sx < 0 && hx > FLT_UWORD_LOG_MIN)
return twom100*twom100; /* underflow */
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/* 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 */
}
/* 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) {
__uint32_t hy;
GET_FLOAT_WORD(hy,y);
SET_FLOAT_WORD(y,hy+(k<<23)); /* add k to y's exponent */
return y;
} else {
__uint32_t hy;
GET_FLOAT_WORD(hy,y);
SET_FLOAT_WORD(y,hy+((k+100)<<23)); /* add k to y's exponent */
return y*twom100;
}
}