0,0 → 1,131 |
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/* @(#)s_modf.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. |
* ==================================================== |
*/ |
|
/* |
FUNCTION |
<<modf>>, <<modff>>---split fractional and integer parts |
|
INDEX |
modf |
INDEX |
modff |
|
ANSI_SYNOPSIS |
#include <math.h> |
double modf(double <[val]>, double *<[ipart]>); |
float modff(float <[val]>, float *<[ipart]>); |
|
TRAD_SYNOPSIS |
#include <math.h> |
double modf(<[val]>, <[ipart]>) |
double <[val]>; |
double *<[ipart]>; |
|
float modff(<[val]>, <[ipart]>) |
float <[val]>; |
float *<[ipart]>; |
|
DESCRIPTION |
<<modf>> splits the double <[val]> apart into an integer part |
and a fractional part, returning the fractional part and |
storing the integer part in <<*<[ipart]>>>. No rounding |
whatsoever is done; the sum of the integer and fractional |
parts is guaranteed to be exactly equal to <[val]>. That |
is, if <[realpart]> = modf(<[val]>, &<[intpart]>); then |
`<<<[realpart]>+<[intpart]>>>' is the same as <[val]>. |
<<modff>> is identical, save that it takes and returns |
<<float>> rather than <<double>> values. |
|
RETURNS |
The fractional part is returned. Each result has the same |
sign as the supplied argument <[val]>. |
|
PORTABILITY |
<<modf>> is ANSI C. <<modff>> is an extension. |
|
QUICKREF |
modf ansi pure |
modff - pure |
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*/ |
|
/* |
* modf(double x, double *iptr) |
* return fraction part of x, and return x's integral part in *iptr. |
* Method: |
* Bit twiddling. |
* |
* Exception: |
* No exception. |
*/ |
|
#include "fdlibm.h" |
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#ifndef _DOUBLE_IS_32BITS |
|
#ifdef __STDC__ |
static const double one = 1.0; |
#else |
static double one = 1.0; |
#endif |
|
#ifdef __STDC__ |
double modf(double x, double *iptr) |
#else |
double modf(x, iptr) |
double x,*iptr; |
#endif |
{ |
__int32_t i0,i1,j0; |
__uint32_t i; |
EXTRACT_WORDS(i0,i1,x); |
j0 = ((i0>>20)&0x7ff)-0x3ff; /* exponent of x */ |
if(j0<20) { /* integer part in high x */ |
if(j0<0) { /* |x|<1 */ |
INSERT_WORDS(*iptr,i0&0x80000000,0); /* *iptr = +-0 */ |
return x; |
} else { |
i = (0x000fffff)>>j0; |
if(((i0&i)|i1)==0) { /* x is integral */ |
__uint32_t high; |
*iptr = x; |
GET_HIGH_WORD(high,x); |
INSERT_WORDS(x,high&0x80000000,0); /* return +-0 */ |
return x; |
} else { |
INSERT_WORDS(*iptr,i0&(~i),0); |
return x - *iptr; |
} |
} |
} else if (j0>51) { /* no fraction part */ |
__uint32_t high; |
*iptr = x*one; |
GET_HIGH_WORD(high,x); |
INSERT_WORDS(x,high&0x80000000,0); /* return +-0 */ |
return x; |
} else { /* fraction part in low x */ |
i = ((__uint32_t)(0xffffffff))>>(j0-20); |
if((i1&i)==0) { /* x is integral */ |
__uint32_t high; |
*iptr = x; |
GET_HIGH_WORD(high,x); |
INSERT_WORDS(x,high&0x80000000,0); /* return +-0 */ |
return x; |
} else { |
INSERT_WORDS(*iptr,i0,i1&(~i)); |
return x - *iptr; |
} |
} |
} |
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#endif /* _DOUBLE_IS_32BITS */ |