Mercurial > hg > octave-lyh > gnulib-hg
changeset 9469:756069cfb5f5
Detect round() bug on NetBSD 3.0/x86.
author | Bruno Haible <bruno@clisp.org> |
---|---|
date | Sun, 11 Nov 2007 15:14:24 +0100 |
parents | 6eda531c067c |
children | 4b48f7a470c2 |
files | ChangeLog doc/functions/round.texi m4/round.m4 |
diffstat | 3 files changed, 49 insertions(+), 2 deletions(-) [+] |
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--- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,8 @@ +2007-11-11 Bruno Haible <bruno@clisp.org> + + * m4/round.m4 (gl_FUNC_ROUND): Test against NetBSD 3.0 bug. + * doc/functions/round.texi: Mention the NetBSD 3.0 bug. + 2007-11-11 Bruno Haible <bruno@clisp.org> * tests/test-argmatch.c (ARGMATCH_DIE): Undefine.
--- a/doc/functions/round.texi +++ b/doc/functions/round.texi @@ -11,6 +11,9 @@ @item This function is missing on some platforms: FreeBSD 5.2.1, OpenBSD 3.8, AIX 5.1, IRIX 6.5, OSF/1 4.0, Solaris 9, Interix 3.5. +@item +This functions returns a wrong result for x = 1/2 - 2^-54 on some platforms: +NetBSD 3.0. @end itemize Portability problems not fixed by Gnulib:
--- a/m4/round.m4 +++ b/m4/round.m4 @@ -1,4 +1,4 @@ -# round.m4 serial 4 +# round.m4 serial 5 dnl Copyright (C) 2007 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, @@ -13,6 +13,44 @@ if test "$ac_cv_have_decl_round" = yes; then gl_CHECK_MATH_LIB([ROUND_LIBM], [x = round (x);]) fi + if test "$ac_cv_have_decl_round" = yes && test "$ROUND_LIBM" != missing; then + dnl Test whether round() produces correct results. On NetBSD 3.0, for + dnl x = 1/2 - 2^-54, the system's round() returns a wrong result. + AC_REQUIRE([AC_PROG_CC]) + AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles + AC_CACHE_CHECK([whether round works], [gl_cv_func_round_works], + [ + save_LIBS="$LIBS" + LIBS="$LIBS $ROUND_LIBM" + AC_TRY_RUN([ +#include <float.h> +#include <math.h> +int main() +{ + /* 2^DBL_MANT_DIG. */ + static const double TWO_MANT_DIG = + /* Assume DBL_MANT_DIG <= 5 * 31. + Use the identity + n = floor(n/5) + floor((n+1)/5) + ... + floor((n+4)/5). */ + (double) (1U << (DBL_MANT_DIG / 5)) + * (double) (1U << ((DBL_MANT_DIG + 1) / 5)) + * (double) (1U << ((DBL_MANT_DIG + 2) / 5)) + * (double) (1U << ((DBL_MANT_DIG + 3) / 5)) + * (double) (1U << ((DBL_MANT_DIG + 4) / 5)); + volatile double x = 0.5 - 0.5 / TWO_MANT_DIG; + exit (x < 0.5 && round (x) != 0.0); +}], [gl_cv_func_round_works=yes], [gl_cv_func_round_works=no], + [case "$host_os" in + netbsd*) gl_cv_func_round_works="guessing no";; + *) gl_cv_func_round_works="guessing yes";; + esac + ]) + LIBS="$save_LIBS" + ]) + case "$gl_cv_func_round_works" in + *no) ROUND_LIBM=missing ;; + esac + fi if test "$ac_cv_have_decl_round" != yes || test "$ROUND_LIBM" = missing; then REPLACE_ROUND=1 AC_LIBOBJ([round]) @@ -20,4 +58,5 @@ gl_FUNC_CEIL_LIBS ROUND_LIBM="$FLOOR_LIBM $CEIL_LIBM" fi - AC_SUBST([ROUND_LIBM])]) + AC_SUBST([ROUND_LIBM]) +])