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

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2000-02-18 03:39:52 +08:00
/* @(#)s_rint.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.
* ====================================================
*/
2009-03-25 Craig Howland <howland@LGSInnovations.com> * libc/include/math.h: (llround, llroundf): Declare. * libm/common/s_llround.c: New file, implementing llround(). * libm/common/sf_llround.c: New file, implementing llroundf(). * libm/common/sf_lround.c: Remove spurious cast in _DOUBLE_IS_32BITS version of function. * libm/common/sf_lrint.c: Ditto. * libm/common/sf_logb.c: Corrected return for subnormal argument by replacing existing function with a version created from sf_ilogb.c. * libm/common/s_logb.c: Ditto, except starting point s_ilogb.c. Also added documentation for logb() and logbf(). * libm/common/s_signbit.c: Add signbit() documentation. * libm/common/s_log2.c: Update return values to match what w_log2.c has, since log2 uses log(); add note about being derived instead of direct. * libm/common/sf_fma.c: Add casts to attempt to get correct results, as well as comments pointing out problems with the implementation. * libm/common/s_fma.c: Add fma() and fmaf() documentation. * libm/common/sf_remquo.c: Incorrect quotient returns for large values corrected by discarding existing function and replacing with Sun verion, with some enhancements. * libm/common/s_remquo.c: Ditto. Add remquo() and remquof() documentation. * libm/common/s_fmax.c: Add fmax() and fmaxf() documentation. * libm/common/s_fmin.c: Add fmin() and fminf() documentation. * libm/common/s_fdim.c: Return NAN for NAN arg, add fdim() and fdimf() documentation. * libm/common/sf_fdim.c: Return NAN for NAN arg, HUGE_VALF for inf arg. * libm/common/s_trunc.c: Add trunc() and truncf() documentation. * libm/common/s_rint.c: Add rint() and rintf() documentation. * libm/common/s_round.c: Add round() and roundf() documentation. * libm/common/s_scalbn.c: Add scalbln() and scalblnf() documentation. * libm/common/s_infinity.c: Add infinity() and infinityf() documentation. * libm/common/s_lround.c: Add lround(), lroundf(), llround(), and llroundf() documentation. * libm/common/s_lrint.c: Add lrint(), lrintf(), llrint(), and llrintf() documentation. * libm/common/isgreater.c: New file for documenting math.h function-like macros isgreater(), isgreaterequal(), isless(), islessequal(), islessgreater(), and isunordered(). * libm/common/s_isnan.c: Add documentation for function-like macros fpclassify(), isfinite(), isinf(), isnan(), and isnormal(). * libm/common/s_nearbyint.c: Add nearbyint() and nearbyintf() documentation. * libm/common/Makefile.am: Add s_llround.c (src); sf_llround.c (fsrc); s_fdim.def, s_fma.def, s_fmax.def, s_fmin.def, s_logb.def, s_lrint.def, s_lround.def, s_nearbyint.def, s_remquo.def, s_rint.def, s_round.def, s_signbit.def, s_trunc.def, and isgreater.def (chobj); re-name all existing chew files (chobj) to match source file base names (put in underscores), delete all special targets for chew files (leaving all to be generated by rule). * libm/common/Makefile.in: regenerate. * libm/math/w_exp2.c: Add "base 2" to documentation description (and delete TRAD_SYNOPSIS). * libm/math/w_gamma.c: Add tgamma() and tgammaf() documentation, along with some history behind the function names. * libm/math/math.tex: Add includes for newly-added documentation (see .def additions to common/Makefile.am and math/Makefile.am in this ChangeLog list), adjusted existing .def file names to match source file base names (added underscores); add mention of HUGE_VALF; rename "Version of library" section to "Error Handling" and add some text about floating-point exception; added section "Standards Compliance And Portability". * libm/math/Makefile.am: Add w_exp2.def (chobj); re-name all existing chew files (chobj) to match source file base names, delete all special targets for chew files (leaving all to be generated by rule). * libm/math/Makefile.in: regenerated * doc/makedoc.c: Change silent ignoring of commands < 5 characters to a failure when reading macro file for commands < 4 characters; add -v (verbose) option for printing some debugging information; get rid of spurious translation of "@*" to "*" (no source files used @*, so no existing doc pages were affected); clean up some compiler warnings. * doc/doc.str: add BUGS and SEEALSO sections (to match texi2pod.pl which has them); Remove ITEM command (redundant with makedoc built-in "o", not used in any present source file so nothing is lost, anyway). * HOWTO: New file to hold information for maintainers regarding how to do things. Initial sections on documentation and ELIX levels.
2009-03-26 03:13:24 +08:00
/*
FUNCTION
<<rint>>, <<rintf>>--round to integer
INDEX
rint
INDEX
rintf
ANSI_SYNOPSIS
#include <math.h>
double rint(double <[x]>);
float rintf(float <[x]>);
DESCRIPTION
The <<rint>> functions round their argument to an integer value in
floating-point format, using the current rounding direction. They
raise the "inexact" floating-point exception if the result differs
in value from the argument. See the <<nearbyint>> functions for the
same function with the "inexact" floating-point exception never being
raised. Newlib does not directly support floating-point exceptions.
The <<rint>> functions are written so that the "inexact" exception is
raised in hardware implementations that support it, even though Newlib
does not provide access.
RETURNS
<[x]> rounded to an integral value, using the current rounding direction.
PORTABILITY
ANSI C, POSIX
SEEALSO
<<nearbyint>>, <<round>>
*/
2000-02-18 03:39:52 +08:00
/*
* rint(x)
* Return x rounded to integral value according to the prevailing
* rounding mode.
* Method:
* Using floating addition.
* Exception:
* Inexact flag raised if x not equal to rint(x).
*/
#include "fdlibm.h"
#ifndef _DOUBLE_IS_32BITS
#ifdef __STDC__
static const double
#else
static double
#endif
TWO52[2]={
4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
-4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
};
#ifdef __STDC__
double rint(double x)
#else
double rint(x)
double x;
#endif
{
__int32_t i0,j0,sx;
__uint32_t i,i1;
double t;
volatile double w;
EXTRACT_WORDS(i0,i1,x);
sx = (i0>>31)&1;
j0 = ((i0>>20)&0x7ff)-0x3ff;
if(j0<20) {
if(j0<0) {
if(((i0&0x7fffffff)|i1)==0) return x;
i1 |= (i0&0x0fffff);
i0 &= 0xfffe0000;
i0 |= ((i1|-i1)>>12)&0x80000;
SET_HIGH_WORD(x,i0);
w = TWO52[sx]+x;
t = w-TWO52[sx];
GET_HIGH_WORD(i0,t);
SET_HIGH_WORD(t,(i0&0x7fffffff)|(sx<<31));
return t;
} else {
i = (0x000fffff)>>j0;
if(((i0&i)|i1)==0) return x; /* x is integral */
i>>=1;
if(((i0&i)|i1)!=0) {
if(j0==19) i1 = 0x40000000; else
i0 = (i0&(~i))|((0x20000)>>j0);
}
}
} else if (j0>51) {
if(j0==0x400) return x+x; /* inf or NaN */
else return x; /* x is integral */
} else {
i = ((__uint32_t)(0xffffffff))>>(j0-20);
if((i1&i)==0) return x; /* x is integral */
i>>=1;
if((i1&i)!=0) i1 = (i1&(~i))|((0x40000000)>>(j0-20));
}
INSERT_WORDS(x,i0,i1);
w = TWO52[sx]+x;
return w-TWO52[sx];
}
#endif /* _DOUBLE_IS_32BITS */