newlib-cygwin/newlib/libm/common/s_modf.c

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2000-02-18 03:39:52 +08:00
/* @(#)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
2005-10-28 Bob Wilson <bob.wilson@acm.org> * libc/misc/unctrl.c: Replace FUNCTION description. * libc/signal/signal.c: Remove documentation for raise and _raise_r. * libc/stdio/getdelim.c: Fix spelling errors. * libc/stdio/getw.c: Put RETURNS on a separate line. Fix punctuation. * libc/stdio/putw.c: Likewise. * libc/stdlib/a64l.c: Fix formatting, spelling and punctuation in documentation. * libc/stdlib/assert.c: Do not capitalize FUNCTION description. * libc/stdlib/efgcvt.c: Add spaces to FUNCTION description. * libc/stdlib/envlock.c: Use em-dash in FUNCTION description. * libc/stdlib/mlock.c: Likewise. * libc/stdlib/mstats.c: Likewise. * libc/time/tzlock.c: Likewise. * libc/stdlib/rand.c: Use "multi-threaded" and "thread-safe" in NOTES. * libc/stdlib/rand48.c: Remove extra space in FUNCTION description and hyphenate "pseudo-random". * libc/string/bcmp.c: Remove extra blank lines in documentation. * libc/string/strncat.c: Likewise. * libc/string/memchr.c: Remove extra ">" character in documentation. * libc/string/strcspn.c: Use "characters" instead of "chars". * libc/string/strpbrk.c: Likewise. * libc/string/strerror_r.c: Capitalize "GNU". * libc/string/strnlen.c: Likewise. * libc/string/strtok.c: Fix formatting, spelling and punctuation in documentation. Use "multi-threaded" and "thread-safe" in NOTES. * libc/string/wcscat.c: Split PORTABILITY into two paragraphs. * libc/string/wcschr.c: Likewise. * libc/string/wcscmp.c: Likewise. * libc/string/wcscpy.c: Likewise. * libc/string/wcscspn.c: Likewise. * libc/string/wcslen.c: Likewise. * libc/string/wcsncat.c: Likewise. * libc/string/wcsncmp.c: Likewise. * libc/string/wcsncpy.c: Likewise. * libc/string/wcsnlen.c: Likewise. * libc/string/wcspbrk.c: Likewise. * libc/string/wcsrchr.c: Likewise. * libc/string/wcsspn.c: Likewise. * libc/string/wmemchr.c: Likewise. * libc/string/wmemcmp.c: Likewise. * libc/string/wmemcpy.c: Likewise. * libc/string/wmemset.c: Likewise. * libc/string/wmemmove.c: Likewise. Also fix FUNCTION description. * libc/string/wcswidth.c: Formatting and punctuation in documentation. * libc/string/wcwidth.c: Likewise. * libm/common/s_modf.c: Remove extra period from documentation. * libm/math/s_isnan.c: Fix formatting, grammar and punctuation in documentation. * libm/mathfp/s_isnan.c: Likewise. * libm/math/s_ldexp.c: Fix punctuation. * libm/mathfp/s_ldexp.c: Likewise. * libm/math/w_log.c: Likewise. * libm/mathfp/s_logarithm.c: Likewise. * libm/math/w_j0.c: Add spaces to FUNCTION description. * libm/mathfp/w_jn.c: Likewise.
2005-10-29 05:21:08 +08:00
is, if <[realpart]> = modf(<[val]>, &<[intpart]>); then
2000-02-18 03:39:52 +08:00
`<<<[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
*/
/*
* 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"
#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;
}
}
}
#endif /* _DOUBLE_IS_32BITS */