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

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2002-06-08 05:59:57 +08:00
/*
* ====================================================
* 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
<<round>>, <<roundf>>--round to integer, to nearest
INDEX
round
INDEX
roundf
ANSI_SYNOPSIS
#include <math.h>
double round(double <[x]>);
float roundf(float <[x]>);
DESCRIPTION
The <<round>> functions round their argument to the nearest integer
value in floating-point format, rounding halfway cases away from zero,
regardless of the current rounding direction. (While the "inexact"
floating-point exception behavior is unspecified by the C standard, the
<<round>> functions are written so that "inexact" is not raised if the
result does not equal the argument, which behavior is as recommended by
IEEE 754 for its related functions.)
RETURNS
<[x]> rounded to an integral value.
PORTABILITY
ANSI C, POSIX
SEEALSO
<<nearbyint>>, <<rint>>
*/
2002-06-08 05:59:57 +08:00
#include "fdlibm.h"
#ifndef _DOUBLE_IS_32BITS
#ifdef __STDC__
double round(double x)
#else
double round(x)
double x;
#endif
{
/* Most significant word, least significant word. */
__int32_t msw, exponent_less_1023;
__uint32_t lsw;
EXTRACT_WORDS(msw, lsw, x);
/* Extract exponent field. */
exponent_less_1023 = ((msw & 0x7ff00000) >> 20) - 1023;
if (exponent_less_1023 < 20)
{
if (exponent_less_1023 < 0)
{
msw &= 0x80000000;
if (exponent_less_1023 == -1)
/* Result is +1.0 or -1.0. */
msw |= (1023 << 20);
lsw = 0;
}
else
{
__uint32_t exponent_mask = 0x000fffff >> exponent_less_1023;
if ((msw & exponent_mask) == 0 && lsw == 0)
/* x in an integral value. */
return x;
msw += 0x00080000 >> exponent_less_1023;
msw &= ~exponent_mask;
lsw = 0;
}
}
else if (exponent_less_1023 > 51)
{
if (exponent_less_1023 == 1024)
/* x is NaN or infinite. */
return x + x;
else
return x;
}
else
{
__uint32_t exponent_mask = 0xffffffff >> (exponent_less_1023 - 20);
__uint32_t tmp;
if ((lsw & exponent_mask) == 0)
/* x is an integral value. */
return x;
tmp = lsw + (1 << (51 - exponent_less_1023));
if (tmp < lsw)
msw += 1;
lsw = tmp;
lsw &= ~exponent_mask;
}
INSERT_WORDS(x, msw, lsw);
return x;
}
#endif /* _DOUBLE_IS_32BITS */