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author | Christopher Faylor <me@cgf.cx> | 2000-02-17 19:39:52 +0000 |
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committer | Christopher Faylor <me@cgf.cx> | 2000-02-17 19:39:52 +0000 |
commit | 8a0efa53e44919bcf5ccb1d3353618a82afdf8bc (patch) | |
tree | 68c3dbf3f2c6fd5d49777def9914d77b5cd4589d /newlib/libm/math/e_remainder.c | |
parent | 1fd5e000ace55b323124c7e556a7a864b972a5c4 (diff) | |
download | newlib-8a0efa53e44919bcf5ccb1d3353618a82afdf8bc.zip newlib-8a0efa53e44919bcf5ccb1d3353618a82afdf8bc.tar.gz newlib-8a0efa53e44919bcf5ccb1d3353618a82afdf8bc.tar.bz2 |
import newlib-2000-02-17 snapshot
Diffstat (limited to 'newlib/libm/math/e_remainder.c')
-rw-r--r-- | newlib/libm/math/e_remainder.c | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/newlib/libm/math/e_remainder.c b/newlib/libm/math/e_remainder.c new file mode 100644 index 0000000..ae7ce64 --- /dev/null +++ b/newlib/libm/math/e_remainder.c @@ -0,0 +1,80 @@ + +/* @(#)e_remainder.c 5.1 93/09/24 */ +/* + * ==================================================== + * 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. + * ==================================================== + */ + +/* __ieee754_remainder(x,p) + * Return : + * returns x REM p = x - [x/p]*p as if in infinite + * precise arithmetic, where [x/p] is the (infinite bit) + * integer nearest x/p (in half way case choose the even one). + * Method : + * Based on fmod() return x-[x/p]chopped*p exactlp. + */ + +#include "fdlibm.h" + +#ifndef _DOUBLE_IS_32BITS + +#ifdef __STDC__ +static const double zero = 0.0; +#else +static double zero = 0.0; +#endif + + +#ifdef __STDC__ + double __ieee754_remainder(double x, double p) +#else + double __ieee754_remainder(x,p) + double x,p; +#endif +{ + __int32_t hx,hp; + __uint32_t sx,lx,lp; + double p_half; + + EXTRACT_WORDS(hx,lx,x); + EXTRACT_WORDS(hp,lp,p); + sx = hx&0x80000000; + hp &= 0x7fffffff; + hx &= 0x7fffffff; + + /* purge off exception values */ + if((hp|lp)==0) return (x*p)/(x*p); /* p = 0 */ + if((hx>=0x7ff00000)|| /* x not finite */ + ((hp>=0x7ff00000)&& /* p is NaN */ + (((hp-0x7ff00000)|lp)!=0))) + return (x*p)/(x*p); + + + if (hp<=0x7fdfffff) x = __ieee754_fmod(x,p+p); /* now x < 2p */ + if (((hx-hp)|(lx-lp))==0) return zero*x; + x = fabs(x); + p = fabs(p); + if (hp<0x00200000) { + if(x+x>p) { + x-=p; + if(x+x>=p) x -= p; + } + } else { + p_half = 0.5*p; + if(x>p_half) { + x-=p; + if(x>=p_half) x -= p; + } + } + GET_HIGH_WORD(hx,x); + SET_HIGH_WORD(x,hx^sx); + return x; +} + +#endif /* defined(_DOUBLE_IS_32BITS) */ |