* 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 <bruno@clisp.org>
+
+ 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 <bruno@clisp.org>
Tests for module 'log2'.
POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/log2f.html}
-Gnulib module: ---
+Gnulib module: log2f
Portability problems fixed by Gnulib:
@itemize
-@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,
+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
@end itemize
--- /dev/null
+/* 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 <http://www.gnu.org/licenses/>. */
+
+#include <config.h>
+
+/* Specification. */
+#include <math.h>
+
+#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
#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)
--- /dev/null
+# 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 <math.h> 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 $ac_cv_func_log2f = yes; then
+ HAVE_LOG2F=1
+ dnl Also check whether it's declared.
+ dnl IRIX 6.5 has log2f() in libm but doesn't declare it in <math.h>.
+ AC_CHECK_DECL([log2f], , [HAVE_DECL_LOG2F=0], [[#include <math.h>]])
+
+ save_LIBS="$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 $LOGF_LIBM" ;;
+ esac
+ fi
+ fi
+])
+
+dnl Test whether log2() works.
+dnl On OSF/1 5.1, log2f(-0.0f) is NaN.
+dnl On Cygwin 1.7.9, log2f(2^13) is not exactly 13.
+AC_DEFUN([gl_FUNC_LOG2F_WORKS],
+[
+ AC_REQUIRE([AC_PROG_CC])
+ AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+ AC_CACHE_CHECK([whether log2f works], [gl_cv_func_log2f_works],
+ [
+ AC_RUN_IFELSE(
+ [AC_LANG_SOURCE([[
+#include <math.h>
+#ifndef log2f /* for Cygwin 1.7.x */
+extern
+#ifdef __cplusplus
+"C"
+#endif
+float log2f (float);
+#endif
+volatile float x;
+volatile float y;
+int main ()
+{
+ int result = 0;
+ /* This test fails on OSF/1 5.1. */
+ x = -0.0f;
+ y = log2f (x);
+ if (!(y + y == y))
+ result |= 1;
+ /* This test fails on Cygwin 1.7.9. */
+ x = 8192.0f;
+ y = log2f (x);
+ if (!(y == 13.0f))
+ result |= 2;
+ return result;
+}
+]])],
+ [gl_cv_func_log2f_works=yes],
+ [gl_cv_func_log2f_works=no],
+ [case "$host_os" in
+ cygwin* | osf*) gl_cv_func_log2f_works="guessing no";;
+ *) gl_cv_func_log2f_works="guessing yes";;
+ esac
+ ])
+ ])
+])
-# 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,
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
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])
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])
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])
--- /dev/null
+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 $REPLACE_LOG2F = 1; then
+ AC_LIBOBJ([log2f])
+fi
+gl_MATH_MODULE_INDICATOR([log2f])
+
+Makefile.am:
+
+Include:
+<math.h>
+
+Link:
+$(LOG2F_LIBM)
+
+License:
+LGPL
+
+Maintainer:
+Bruno Haible
-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''@/$(GNULIB_MODFL)/g' \
-e 's|@''HAVE_DECL_LOGL''@|$(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' \
-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' \
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