# HG changeset patch # User Bruno Haible # Date 1331485032 -3600 # Node ID 2f6973f75a061fbd85595241274fd3fbf5ae15b3 # Parent 05117c6c2f05022eff6cac88a58777c9286263d6 New module 'log2f'. * lib/math.in.h (log2f): New declaration. * lib/log2f.c: New file. * m4/log2f.m4: New file. * m4/math_h.m4 (gl_MATH_H): Test whether log2f is declared. (gl_MATH_H_DEFAULTS): Initialize GNULIB_LOG2F, HAVE_DECL_LOG2F, REPLACE_LOG2F. * modules/math (Makefile.am): Substitute GNULIB_LOG2F, HAVE_DECL_LOG2F, REPLACE_LOG2F. * modules/log2f: New file. * tests/test-math-c++.cc: Check the declaration of log2f. * doc/posix-functions/log2f.texi: Mention the new module and the IRIX and OSF/1 and Cygwin problems. diff --git a/ChangeLog b/ChangeLog --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,19 @@ +2012-03-11 Bruno Haible + + New module 'log2f'. + * lib/math.in.h (log2f): New declaration. + * lib/log2f.c: New file. + * m4/log2f.m4: New file. + * m4/math_h.m4 (gl_MATH_H): Test whether log2f is declared. + (gl_MATH_H_DEFAULTS): Initialize GNULIB_LOG2F, HAVE_DECL_LOG2F, + REPLACE_LOG2F. + * modules/math (Makefile.am): Substitute GNULIB_LOG2F, HAVE_DECL_LOG2F, + REPLACE_LOG2F. + * modules/log2f: New file. + * tests/test-math-c++.cc: Check the declaration of log2f. + * doc/posix-functions/log2f.texi: Mention the new module and the IRIX + and OSF/1 and Cygwin problems. + 2012-03-11 Bruno Haible Tests for module 'log2'. diff --git a/doc/posix-functions/log2f.texi b/doc/posix-functions/log2f.texi --- a/doc/posix-functions/log2f.texi +++ b/doc/posix-functions/log2f.texi @@ -4,19 +4,28 @@ POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/log2f.html} -Gnulib module: --- +Gnulib module: log2f Portability problems fixed by Gnulib: @itemize +@item +This function is missing on some platforms: +FreeBSD 6.0, NetBSD 3.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, older IRIX 6.5, Solaris 9, MSVC 9, +Interix 3.5. +@item +This function is not declared on some platforms: +IRIX 6.5. +@item +This function is only provided as a macro on some platforms: +Cygwin 1.5.x. +@item +This function returns a wrong value for a minus zero argument on some platforms: +OSF/1 5.1. +@item +This function returns slightly wrong values for exact powers of 2 on some platforms: +Cygwin 1.7.9. @end itemize Portability problems not fixed by Gnulib: @itemize -@item -This function is missing on some platforms: -FreeBSD 6.0, NetBSD 3.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, IRIX 6.5, Solaris 9, MSVC 9, -Interix 3.5. -@item -This function is only provided as a macro on some platforms: -Cygwin 1.5.x. @end itemize diff --git a/lib/log2f.c b/lib/log2f.c new file mode 100644 --- /dev/null +++ b/lib/log2f.c @@ -0,0 +1,85 @@ +/* Base 2 logarithm. + Copyright (C) 2012 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#include + +/* Specification. */ +#include + +#if HAVE_LOG2 + +float +log2f (float x) +{ + return (float) log2 ((double) x); +} + +#else + +/* Best possible approximation of log(2) as a 'float'. */ +#define LOG2 0.693147180559945309417232121458176568075f + +/* Best possible approximation of 1/log(2) as a 'float'. */ +#define LOG2_INVERSE 1.44269504088896340735992468100189213743f + +/* sqrt(0.5). */ +#define SQRT_HALF 0.707106781186547524400844362104849039284f + +float +log2f (float x) +{ + if (isnanf (x)) + return x; + + if (x <= 0.0f) + { + if (x == 0.0f) + /* Return -Infinity. */ + return - HUGE_VALF; + else + { + /* Return NaN. */ +#if defined _MSC_VER + static float zero; + return zero / zero; +#else + return 0.0f / 0.0f; +#endif + } + } + + /* Decompose x into + x = 2^e * y + where + e is an integer, + 1/2 < y < 2. + Then log2(x) = e + log2(y) = e + log(y)/log(2). */ + { + int e; + float y; + + y = frexpf (x, &e); + if (y < SQRT_HALF) + { + y = 2.0f * y; + e = e - 1; + } + + return (float) e + logf (y) * LOG2_INVERSE; + } +} + +#endif diff --git a/lib/math.in.h b/lib/math.in.h --- a/lib/math.in.h +++ b/lib/math.in.h @@ -1291,6 +1291,30 @@ #endif +#if @GNULIB_LOG2F@ +# if @REPLACE_LOG2F@ +# if !(defined __cplusplus && defined GNULIB_NAMESPACE) +# undef log2f +# define log2f rpl_log2f +# endif +_GL_FUNCDECL_RPL (log2f, float, (float x)); +_GL_CXXALIAS_RPL (log2f, float, (float x)); +# else +# if !@HAVE_DECL_LOG2F@ +# undef log2f +_GL_FUNCDECL_SYS (log2f, float, (float x)); +# endif +_GL_CXXALIAS_SYS (log2f, float, (float x)); +# endif +_GL_CXXALIASWARN (log2f); +#elif defined GNULIB_POSIXCHECK +# undef log2f +# if HAVE_RAW_DECL_LOG2F +_GL_WARN_ON_USE (log2f, "log2f is unportable - " + "use gnulib module log2f for portability"); +# endif +#endif + #if @GNULIB_LOG2@ # if @REPLACE_LOG2@ # if !(defined __cplusplus && defined GNULIB_NAMESPACE) diff --git a/m4/log2f.m4 b/m4/log2f.m4 new file mode 100644 --- /dev/null +++ b/m4/log2f.m4 @@ -0,0 +1,116 @@ +# log2f.m4 serial 1 +dnl Copyright (C) 2010-2012 Free Software Foundation, Inc. +dnl This file is free software; the Free Software Foundation +dnl gives unlimited permission to copy and/or distribute it, +dnl with or without modifications, as long as this notice is preserved. + +AC_DEFUN([gl_FUNC_LOG2F], +[ + AC_REQUIRE([gl_MATH_H_DEFAULTS]) + AC_REQUIRE([gl_FUNC_LOG2]) + + dnl Persuade glibc to declare log2f(). + AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) + + dnl Determine LOG2F_LIBM. + gl_COMMON_DOUBLE_MATHFUNC([log2f]) + + dnl Test whether log2f() exists. + save_LIBS="$LIBS" + LIBS="$LIBS $LOG2F_LIBM" + AC_CHECK_FUNCS([log2f]) + LIBS="$save_LIBS" + if test $ac_cv_func_log2f = yes; then + HAVE_LOG2F=1 + dnl Also check whether it's declared. + dnl IRIX 6.5 has log2f() in libm but doesn't declare it in . + AC_CHECK_DECL([log2f], , [HAVE_DECL_LOG2F=0], [[#include ]]) + + save_LIBS="$LIBS" + LIBS="$LIBS $LOG2F_LIBM" + gl_FUNC_LOG2F_WORKS + LIBS="$save_LIBS" + case "$gl_cv_func_log2f_works" in + *yes) ;; + *) REPLACE_LOG2F=1 ;; + esac + else + HAVE_LOG2F=0 + HAVE_DECL_LOG2F=0 + fi + if test $HAVE_LOG2F = 0 || test $REPLACE_LOG2F = 1; then + dnl Find libraries needed to link lib/log2f.c. + if test $ac_cv_func_log2 = yes; then + AC_DEFINE([HAVE_LOG2], [1], + [Define to 1 if the log2() function is available in libc or libm.]) + LOG2F_LIBM="$LOG2_LIBM" + else + AC_REQUIRE([gl_FUNC_ISNANF]) + AC_REQUIRE([gl_FUNC_FREXPF]) + AC_REQUIRE([gl_FUNC_LOGF]) + LOG2F_LIBM= + dnl Append $ISNANF_LIBM to LOG2F_LIBM, avoiding gratuitous duplicates. + case " $LOG2F_LIBM " in + *" $ISNANF_LIBM "*) ;; + *) LOG2F_LIBM="$LOG2F_LIBM $ISNANF_LIBM" ;; + esac + dnl Append $FREXPF_LIBM to LOG2F_LIBM, avoiding gratuitous duplicates. + case " $LOG2F_LIBM " in + *" $FREXPF_LIBM "*) ;; + *) LOG2F_LIBM="$LOG2F_LIBM $FREXPF_LIBM" ;; + esac + dnl Append $LOGF_LIBM to LOG2F_LIBM, avoiding gratuitous duplicates. + case " $LOG2F_LIBM " in + *" $LOGF_LIBM "*) ;; + *) LOG2F_LIBM="$LOG2F_LIBM $LOGF_LIBM" ;; + esac + fi + fi +]) + +dnl Test whether log2() works. +dnl On OSF/1 5.1, log2f(-0.0f) is NaN. +dnl On Cygwin 1.7.9, log2f(2^13) is not exactly 13. +AC_DEFUN([gl_FUNC_LOG2F_WORKS], +[ + AC_REQUIRE([AC_PROG_CC]) + AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles + AC_CACHE_CHECK([whether log2f works], [gl_cv_func_log2f_works], + [ + AC_RUN_IFELSE( + [AC_LANG_SOURCE([[ +#include +#ifndef log2f /* for Cygwin 1.7.x */ +extern +#ifdef __cplusplus +"C" +#endif +float log2f (float); +#endif +volatile float x; +volatile float y; +int main () +{ + int result = 0; + /* This test fails on OSF/1 5.1. */ + x = -0.0f; + y = log2f (x); + if (!(y + y == y)) + result |= 1; + /* This test fails on Cygwin 1.7.9. */ + x = 8192.0f; + y = log2f (x); + if (!(y == 13.0f)) + result |= 2; + return result; +} +]])], + [gl_cv_func_log2f_works=yes], + [gl_cv_func_log2f_works=no], + [case "$host_os" in + cygwin* | osf*) gl_cv_func_log2f_works="guessing no";; + *) gl_cv_func_log2f_works="guessing yes";; + esac + ]) + ]) +]) diff --git a/m4/math_h.m4 b/m4/math_h.m4 --- a/m4/math_h.m4 +++ b/m4/math_h.m4 @@ -1,4 +1,4 @@ -# math_h.m4 serial 101 +# math_h.m4 serial 102 dnl Copyright (C) 2007-2012 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, @@ -44,7 +44,8 @@ expf expl exp2 exp2f exp2l expm1 expm1f expm1l fabsf fabsl floorf floorl fma fmaf fmal fmod fmodf fmodl frexpf frexpl hypotf hypotl - ldexpf ldexpl logb log logf logl log10f log10l log1p log1pf log1pl log2 + ldexpf ldexpl + logb log logf logl log10f log10l log1p log1pf log1pl log2 log2f modf modff modfl powf remainder remainderf remainderl rint rintf rintl round roundf roundl sinf sinl sinhf sqrtf sqrtl @@ -124,6 +125,7 @@ GNULIB_LOG1PF=0; AC_SUBST([GNULIB_LOG1PF]) GNULIB_LOG1PL=0; AC_SUBST([GNULIB_LOG1PL]) GNULIB_LOG2=0; AC_SUBST([GNULIB_LOG2]) + GNULIB_LOG2F=0; AC_SUBST([GNULIB_LOG2F]) GNULIB_MODF=0; AC_SUBST([GNULIB_MODF]) GNULIB_MODFF=0; AC_SUBST([GNULIB_MODFF]) GNULIB_MODFL=0; AC_SUBST([GNULIB_MODFL]) @@ -227,6 +229,7 @@ HAVE_DECL_LOGL=1; AC_SUBST([HAVE_DECL_LOGL]) HAVE_DECL_LOG10L=1; AC_SUBST([HAVE_DECL_LOG10L]) HAVE_DECL_LOG2=1; AC_SUBST([HAVE_DECL_LOG2]) + HAVE_DECL_LOG2F=1; AC_SUBST([HAVE_DECL_LOG2F]) HAVE_DECL_REMAINDER=1; AC_SUBST([HAVE_DECL_REMAINDER]) HAVE_DECL_REMAINDERL=1; AC_SUBST([HAVE_DECL_REMAINDERL]) HAVE_DECL_RINTF=1; AC_SUBST([HAVE_DECL_RINTF]) @@ -276,6 +279,7 @@ REPLACE_LOG1PF=0; AC_SUBST([REPLACE_LOG1PF]) REPLACE_LOG1PL=0; AC_SUBST([REPLACE_LOG1PL]) REPLACE_LOG2=0; AC_SUBST([REPLACE_LOG2]) + REPLACE_LOG2F=0; AC_SUBST([REPLACE_LOG2F]) REPLACE_MODF=0; AC_SUBST([REPLACE_MODF]) REPLACE_MODFF=0; AC_SUBST([REPLACE_MODFF]) REPLACE_MODFL=0; AC_SUBST([REPLACE_MODFL]) diff --git a/modules/log2f b/modules/log2f new file mode 100644 --- /dev/null +++ b/modules/log2f @@ -0,0 +1,35 @@ +Description: +log2f() function: base 2 logarithm. + +Files: +lib/log2f.c +m4/log2f.m4 + +Depends-on: +math +extensions +log2 [test $HAVE_LOG2F = 0 || test $REPLACE_LOG2F = 1] +isnanf [test $HAVE_LOG2F = 0 || test $REPLACE_LOG2F = 1] +frexpf [test $HAVE_LOG2F = 0 || test $REPLACE_LOG2F = 1] +logf [test $HAVE_LOG2F = 0 || test $REPLACE_LOG2F = 1] + +configure.ac: +gl_FUNC_LOG2F +if test $HAVE_LOG2F = 0 || test $REPLACE_LOG2F = 1; then + AC_LIBOBJ([log2f]) +fi +gl_MATH_MODULE_INDICATOR([log2f]) + +Makefile.am: + +Include: + + +Link: +$(LOG2F_LIBM) + +License: +LGPL + +Maintainer: +Bruno Haible diff --git a/modules/math b/modules/math --- a/modules/math +++ b/modules/math @@ -90,6 +90,7 @@ -e 's/@''GNULIB_LOG1PF''@/$(GNULIB_LOG1PF)/g' \ -e 's/@''GNULIB_LOG1PL''@/$(GNULIB_LOG1PL)/g' \ -e 's/@''GNULIB_LOG2''@/$(GNULIB_LOG2)/g' \ + -e 's/@''GNULIB_LOG2F''@/$(GNULIB_LOG2F)/g' \ -e 's/@''GNULIB_MODF''@/$(GNULIB_MODF)/g' \ -e 's/@''GNULIB_MODFF''@/$(GNULIB_MODFF)/g' \ -e 's/@''GNULIB_MODFL''@/$(GNULIB_MODFL)/g' \ @@ -193,6 +194,7 @@ -e 's|@''HAVE_DECL_LOGL''@|$(HAVE_DECL_LOGL)|g' \ -e 's|@''HAVE_DECL_LOG10L''@|$(HAVE_DECL_LOG10L)|g' \ -e 's|@''HAVE_DECL_LOG2''@|$(HAVE_DECL_LOG2)|g' \ + -e 's|@''HAVE_DECL_LOG2F''@|$(HAVE_DECL_LOG2F)|g' \ -e 's|@''HAVE_DECL_REMAINDER''@|$(HAVE_DECL_REMAINDER)|g' \ -e 's|@''HAVE_DECL_REMAINDERL''@|$(HAVE_DECL_REMAINDERL)|g' \ -e 's|@''HAVE_DECL_RINTF''@|$(HAVE_DECL_RINTF)|g' \ @@ -244,6 +246,7 @@ -e 's|@''REPLACE_LOG1PF''@|$(REPLACE_LOG1PF)|g' \ -e 's|@''REPLACE_LOG1PL''@|$(REPLACE_LOG1PL)|g' \ -e 's|@''REPLACE_LOG2''@|$(REPLACE_LOG2)|g' \ + -e 's|@''REPLACE_LOG2F''@|$(REPLACE_LOG2F)|g' \ -e 's|@''REPLACE_MODF''@|$(REPLACE_MODF)|g' \ -e 's|@''REPLACE_MODFF''@|$(REPLACE_MODFF)|g' \ -e 's|@''REPLACE_MODFL''@|$(REPLACE_MODFL)|g' \ diff --git a/tests/test-math-c++.cc b/tests/test-math-c++.cc --- a/tests/test-math-c++.cc +++ b/tests/test-math-c++.cc @@ -241,6 +241,9 @@ SIGNATURE_CHECK (GNULIB_NAMESPACE::log10f, float, (float)); #endif +#if GNULIB_TEST_LOG2F +SIGNATURE_CHECK (GNULIB_NAMESPACE::log2f, float, (float)); +#endif #if GNULIB_TEST_LOG2 SIGNATURE_CHECK (GNULIB_NAMESPACE::log2, double, (double)); #endif