New module 'log2l'.

* lib/math.in.h (log2l): New declaration.
* lib/log2l.c: New file.
* m4/log2l.m4: New file.
* m4/math_h.m4 (gl_MATH_H): Test whether log2l is declared.
(gl_MATH_H_DEFAULTS): Initialize GNULIB_LOG2L, HAVE_DECL_LOG2L,
REPLACE_LOG2L.
* modules/math (Makefile.am): Substitute GNULIB_LOG2L, HAVE_DECL_LOG2L,
REPLACE_LOG2L.
* modules/log2l: New file.
* tests/test-math-c++.cc: Check the declaration of log2l.
* doc/posix-functions/log2l.texi: Mention the new module and the IRIX
and OSF/1 problems.

diff --git a/ChangeLog b/ChangeLog
index ab635b1..76b7a29 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,21 @@
 2012-03-11  Bruno Haible  <bruno@clisp.org>
 
 2012-03-11  Bruno Haible  <bruno@clisp.org>
 

+       New module 'log2l'.
+       * lib/math.in.h (log2l): New declaration.
+       * lib/log2l.c: New file.
+       * m4/log2l.m4: New file.
+       * m4/math_h.m4 (gl_MATH_H): Test whether log2l is declared.
+       (gl_MATH_H_DEFAULTS): Initialize GNULIB_LOG2L, HAVE_DECL_LOG2L,
+       REPLACE_LOG2L.
+       * modules/math (Makefile.am): Substitute GNULIB_LOG2L, HAVE_DECL_LOG2L,
+       REPLACE_LOG2L.
+       * modules/log2l: New file.
+       * tests/test-math-c++.cc: Check the declaration of log2l.
+       * doc/posix-functions/log2l.texi: Mention the new module and the IRIX
+       and OSF/1 problems.
+
+2012-03-11  Bruno Haible  <bruno@clisp.org>
+

        Tests for module 'log2f'.
        * modules/log2f-tests: New file.
        * tests/test-log2f.c: New file.
        Tests for module 'log2f'.
        * modules/log2f-tests: New file.
        * tests/test-log2f.c: New file.

diff --git a/doc/posix-functions/log2l.texi b/doc/posix-functions/log2l.texi
index 2db3cbb..73491b0 100644 (file)
--- a/doc/posix-functions/log2l.texi
+++ b/doc/posix-functions/log2l.texi
@@ -4,15 +4,21 @@
 
 POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/log2l.html}
 
 
 POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/log2l.html}
 

-Gnulib module: ---
+Gnulib module: log2l

 
 Portability problems fixed by Gnulib:
 @itemize
 
 Portability problems fixed by Gnulib:
 @itemize

+@item
+This function is missing on some platforms:
+FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11, older IRIX 6.5, Solaris 9, Cygwin, MSVC 9, Interix 3.5, BeOS.
+@item
+This function is not declared on some platforms:
+IRIX 6.5.
+@item
+This function returns a wrong value for a minus zero argument on some platforms:
+OSF/1 5.1.

 @end itemize
 
 Portability problems not 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 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11, IRIX 6.5, Solaris 9, Cygwin, MSVC 9, Interix 3.5, BeOS.

 @end itemize
 @end itemize

diff --git a/lib/log2l.c b/lib/log2l.c
new file mode 100644 (file)
index 0000000..cc69605
--- /dev/null
+++ b/lib/log2l.c
@@ -0,0 +1,85 @@
+/* Base 2 logarithm.
+   Copyright (C) 2011-2012 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_SAME_LONG_DOUBLE_AS_DOUBLE
+
+long double
+log2l (long double x)
+{
+  return log2 (x);
+}
+
+#else
+
+/* Best possible approximation of log(2) as a 'long double'.  */
+#define LOG2 0.693147180559945309417232121458176568075L
+
+/* Best possible approximation of 1/log(2) as a 'long double'.  */
+#define LOG2_INVERSE 1.44269504088896340735992468100189213743L
+
+/* sqrt(0.5).  */
+#define SQRT_HALF 0.707106781186547524400844362104849039284L
+
+long double
+log2l (long double x)
+{
+  if (isnanl (x))
+    return x;
+
+  if (x <= 0.0L)
+    {
+      if (x == 0.0L)
+        /* Return -Infinity.  */
+        return - HUGE_VALL;
+      else
+        {
+          /* Return NaN.  */
+#if defined _MSC_VER || (defined __sgi && !defined __GNUC__)
+          static long double zero;
+          return zero / zero;
+#else
+          return 0.0L / 0.0L;
+#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;
+    long double y;
+
+    y = frexpl (x, &e);
+    if (y < SQRT_HALF)
+      {
+        y = 2.0L * y;
+        e = e - 1;
+      }
+
+    return (long double) e + logl (y) * LOG2_INVERSE;
+  }
+}
+
+#endif

diff --git a/lib/math.in.h b/lib/math.in.h
index 57b71d5..77b3253 100644 (file)
--- a/lib/math.in.h
+++ b/lib/math.in.h
@@ -1339,6 +1339,29 @@ _GL_WARN_ON_USE (log2, "log2 is unportable - "
 # endif
 #endif
 
 # endif
 #endif
 

+#if @GNULIB_LOG2L@
+# if @REPLACE_LOG2L@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef log2l
+#   define log2l rpl_log2l
+#  endif
+_GL_FUNCDECL_RPL (log2l, long double, (long double x));
+_GL_CXXALIAS_RPL (log2l, long double, (long double x));
+# else
+#  if !@HAVE_DECL_LOG2L@
+_GL_FUNCDECL_SYS (log2l, long double, (long double x));
+#  endif
+_GL_CXXALIAS_SYS (log2l, long double, (long double x));
+# endif
+_GL_CXXALIASWARN (log2l);
+#elif defined GNULIB_POSIXCHECK
+# undef log2l
+# if HAVE_RAW_DECL_LOG2L
+_GL_WARN_ON_USE (log2l, "log2l is unportable - "
+                 "use gnulib module log2l for portability");
+# endif
+#endif
+

 
 #if @GNULIB_MODFF@
 # if @REPLACE_MODFF@
 
 #if @GNULIB_MODFF@
 # if @REPLACE_MODFF@

diff --git a/m4/log2l.m4 b/m4/log2l.m4
new file mode 100644 (file)
index 0000000..d90a615
--- /dev/null
+++ b/m4/log2l.m4
@@ -0,0 +1,108 @@
+# log2l.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_LOG2L],
+[
+  AC_REQUIRE([gl_MATH_H_DEFAULTS])
+  AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
+  AC_REQUIRE([gl_FUNC_LOG2])
+
+  dnl Persuade glibc <math.h> to declare log2l().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
+  dnl Test whether log2l() exists. Assume that log2l(), if it exists, is
+  dnl defined in the same library as log2().
+  save_LIBS="$LIBS"
+  LIBS="$LIBS $LOG2_LIBM"
+  AC_CHECK_FUNCS([log2l])
+  LIBS="$save_LIBS"
+  if test $ac_cv_func_log2l = yes; then
+    LOG2L_LIBM="$LOG2_LIBM"
+    HAVE_LOG2L=1
+    dnl Also check whether it's declared.
+    dnl IRIX 6.5 has log2l() in libm but doesn't declare it in <math.h>.
+    AC_CHECK_DECL([log2l], , [HAVE_DECL_LOG2L=0], [[#include <math.h>]])
+
+    save_LIBS="$LIBS"
+    LIBS="$LIBS $LOG2L_LIBM"
+    gl_FUNC_LOG2L_WORKS
+    LIBS="$save_LIBS"
+    case "$gl_cv_func_log2l_works" in
+      *yes) ;;
+      *) REPLACE_LOG2L=1 ;;
+    esac
+  else
+    HAVE_LOG2L=0
+    HAVE_DECL_LOG2L=0
+  fi
+  if test $HAVE_LOG2L = 0 || test $REPLACE_LOG2L = 1; then
+    dnl Find libraries needed to link lib/log2l.c.
+    if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
+      LOG2L_LIBM="$LOG2_LIBM"
+    else
+      AC_REQUIRE([gl_FUNC_ISNANL])
+      AC_REQUIRE([gl_FUNC_FREXPL])
+      AC_REQUIRE([gl_FUNC_LOGL])
+      LOG2L_LIBM=
+      dnl Append $ISNANL_LIBM to LOG2L_LIBM, avoiding gratuitous duplicates.
+      case " $LOG2L_LIBM " in
+        *" $ISNANL_LIBM "*) ;;
+        *) LOG2L_LIBM="$LOG2L_LIBM $ISNANL_LIBM" ;;
+      esac
+      dnl Append $FREXPL_LIBM to LOG2L_LIBM, avoiding gratuitous duplicates.
+      case " $LOG2L_LIBM " in
+        *" $FREXPL_LIBM "*) ;;
+        *) LOG2L_LIBM="$LOG2L_LIBM $FREXPL_LIBM" ;;
+      esac
+      dnl Append $LOGL_LIBM to LOG2L_LIBM, avoiding gratuitous duplicates.
+      case " $LOG2L_LIBM " in
+        *" $LOGL_LIBM "*) ;;
+        *) LOG2L_LIBM="$LOG2L_LIBM $LOGL_LIBM" ;;
+      esac
+    fi
+  fi
+  AC_SUBST([LOG2L_LIBM])
+])
+
+dnl Test whether log2l() works.
+dnl On OSF/1 5.1, log2l(-0.0) is NaN.
+AC_DEFUN([gl_FUNC_LOG2L_WORKS],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether log2l works], [gl_cv_func_log2l_works],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <math.h>
+#ifndef log2l /* for AIX */
+extern
+#ifdef __cplusplus
+"C"
+#endif
+long double log2l (long double);
+#endif
+volatile long double x;
+volatile long double y;
+int main ()
+{
+  /* This test fails on OSF/1 5.1.  */
+  x = -0.0L;
+  y = log2l (x);
+  if (!(y + y == y))
+    return 1;
+  return 0;
+}
+]])],
+        [gl_cv_func_log2l_works=yes],
+        [gl_cv_func_log2l_works=no],
+        [case "$host_os" in
+           osf*) gl_cv_func_log2l_works="guessing no";;
+           *)    gl_cv_func_log2l_works="guessing yes";;
+         esac
+        ])
+    ])
+])

diff --git a/m4/math_h.m4 b/m4/math_h.m4
index ec15340..d48fd97 100644 (file)
--- a/m4/math_h.m4
+++ b/m4/math_h.m4
@@ -1,4 +1,4 @@
-# math_h.m4 serial 102
+# math_h.m4 serial 103

 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,
 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,


@@ -45,7 +45,7 @@ AC_DEFUN([gl_MATH_H],
      fabsf fabsl floorf floorl fma fmaf fmal
      fmod fmodf fmodl frexpf frexpl hypotf hypotl
      ldexpf ldexpl
      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 log2f
+     logb log logf logl log10f log10l log1p log1pf log1pl log2 log2f log2l

      modf modff modfl powf
      remainder remainderf remainderl
      rint rintf rintl round roundf roundl sinf sinl sinhf sqrtf sqrtl
      modf modff modfl powf
      remainder remainderf remainderl
      rint rintf rintl round roundf roundl sinf sinl sinhf sqrtf sqrtl


@@ -126,6 +126,7 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   GNULIB_LOG1PL=0;     AC_SUBST([GNULIB_LOG1PL])
   GNULIB_LOG2=0;       AC_SUBST([GNULIB_LOG2])
   GNULIB_LOG2F=0;      AC_SUBST([GNULIB_LOG2F])
   GNULIB_LOG1PL=0;     AC_SUBST([GNULIB_LOG1PL])
   GNULIB_LOG2=0;       AC_SUBST([GNULIB_LOG2])
   GNULIB_LOG2F=0;      AC_SUBST([GNULIB_LOG2F])

+  GNULIB_LOG2L=0;      AC_SUBST([GNULIB_LOG2L])

   GNULIB_MODF=0;       AC_SUBST([GNULIB_MODF])
   GNULIB_MODFF=0;      AC_SUBST([GNULIB_MODFF])
   GNULIB_MODFL=0;      AC_SUBST([GNULIB_MODFL])
   GNULIB_MODF=0;       AC_SUBST([GNULIB_MODF])
   GNULIB_MODFF=0;      AC_SUBST([GNULIB_MODFF])
   GNULIB_MODFL=0;      AC_SUBST([GNULIB_MODFL])


@@ -230,6 +231,7 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   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_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_LOG2L=1;           AC_SUBST([HAVE_DECL_LOG2L])

   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])
   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])


@@ -280,6 +282,7 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   REPLACE_LOG1PL=0;            AC_SUBST([REPLACE_LOG1PL])
   REPLACE_LOG2=0;              AC_SUBST([REPLACE_LOG2])
   REPLACE_LOG2F=0;             AC_SUBST([REPLACE_LOG2F])
   REPLACE_LOG1PL=0;            AC_SUBST([REPLACE_LOG1PL])
   REPLACE_LOG2=0;              AC_SUBST([REPLACE_LOG2])
   REPLACE_LOG2F=0;             AC_SUBST([REPLACE_LOG2F])

+  REPLACE_LOG2L=0;             AC_SUBST([REPLACE_LOG2L])

   REPLACE_MODF=0;              AC_SUBST([REPLACE_MODF])
   REPLACE_MODFF=0;             AC_SUBST([REPLACE_MODFF])
   REPLACE_MODFL=0;             AC_SUBST([REPLACE_MODFL])
   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/log2l b/modules/log2l
new file mode 100644 (file)
index 0000000..848f6d4
--- /dev/null
+++ b/modules/log2l
@@ -0,0 +1,35 @@
+Description:
+log2() function: base 2 logarithm.
+
+Files:
+lib/log2l.c
+m4/log2l.m4
+
+Depends-on:
+math
+extensions
+log2            [{ test $HAVE_LOG2L = 0 || test $REPLACE_LOG2L = 1; } && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1]
+isnanl          [{ test $HAVE_LOG2L = 0 || test $REPLACE_LOG2L = 1; } && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
+frexpl          [{ test $HAVE_LOG2L = 0 || test $REPLACE_LOG2L = 1; } && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
+logl            [{ test $HAVE_LOG2L = 0 || test $REPLACE_LOG2L = 1; } && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
+
+configure.ac:
+gl_FUNC_LOG2L
+if test $HAVE_LOG2L = 0 || test $REPLACE_LOG2L = 1; then
+  AC_LIBOBJ([log2l])
+fi
+gl_MATH_MODULE_INDICATOR([log2l])
+
+Makefile.am:
+
+Include:
+<math.h>
+
+Link:
+$(LOG2L_LIBM)
+
+License:
+LGPL
+
+Maintainer:
+Bruno Haible

diff --git a/modules/math b/modules/math
index 7382974..46d0455 100644 (file)
--- a/modules/math
+++ b/modules/math
@@ -91,6 +91,7 @@ math.h: math.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(
              -e 's/@''GNULIB_LOG1PL''@/$(GNULIB_LOG1PL)/g' \
              -e 's/@''GNULIB_LOG2''@/$(GNULIB_LOG2)/g' \
              -e 's/@''GNULIB_LOG2F''@/$(GNULIB_LOG2F)/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_LOG2L''@/$(GNULIB_LOG2L)/g' \

              -e 's/@''GNULIB_MODF''@/$(GNULIB_MODF)/g' \
              -e 's/@''GNULIB_MODFF''@/$(GNULIB_MODFF)/g' \
              -e 's/@''GNULIB_MODFL''@/$(GNULIB_MODFL)/g' \
              -e 's/@''GNULIB_MODF''@/$(GNULIB_MODF)/g' \
              -e 's/@''GNULIB_MODFF''@/$(GNULIB_MODFF)/g' \
              -e 's/@''GNULIB_MODFL''@/$(GNULIB_MODFL)/g' \


@@ -195,6 +196,7 @@ math.h: math.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(
              -e 's|@''HAVE_DECL_LOG10L''@|$(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_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_LOG2L''@|$(HAVE_DECL_LOG2L)|g' \

              -e 's|@''HAVE_DECL_REMAINDER''@|$(HAVE_DECL_REMAINDER)|g' \
              -e 's|@''HAVE_DECL_REMAINDERL''@|$(HAVE_DECL_REMAINDERL)|g' \
              -e 's|@''HAVE_DECL_RINTF''@|$(HAVE_DECL_RINTF)|g' \
              -e 's|@''HAVE_DECL_REMAINDER''@|$(HAVE_DECL_REMAINDER)|g' \
              -e 's|@''HAVE_DECL_REMAINDERL''@|$(HAVE_DECL_REMAINDERL)|g' \
              -e 's|@''HAVE_DECL_RINTF''@|$(HAVE_DECL_RINTF)|g' \


@@ -247,6 +249,7 @@ math.h: math.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(
              -e 's|@''REPLACE_LOG1PL''@|$(REPLACE_LOG1PL)|g' \
              -e 's|@''REPLACE_LOG2''@|$(REPLACE_LOG2)|g' \
              -e 's|@''REPLACE_LOG2F''@|$(REPLACE_LOG2F)|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_LOG2L''@|$(REPLACE_LOG2L)|g' \

              -e 's|@''REPLACE_MODF''@|$(REPLACE_MODF)|g' \
              -e 's|@''REPLACE_MODFF''@|$(REPLACE_MODFF)|g' \
              -e 's|@''REPLACE_MODFL''@|$(REPLACE_MODFL)|g' \
              -e 's|@''REPLACE_MODF''@|$(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
index 6351458..9caa951 100644 (file)
--- a/tests/test-math-c++.cc
+++ b/tests/test-math-c++.cc
@@ -247,6 +247,9 @@ SIGNATURE_CHECK (GNULIB_NAMESPACE::log2f, float, (float));
 #if GNULIB_TEST_LOG2
 SIGNATURE_CHECK (GNULIB_NAMESPACE::log2, double, (double));
 #endif
 #if GNULIB_TEST_LOG2
 SIGNATURE_CHECK (GNULIB_NAMESPACE::log2, double, (double));
 #endif

+#if GNULIB_TEST_LOG2L
+SIGNATURE_CHECK (GNULIB_NAMESPACE::log2l, long double, (long double));
+#endif

 
 #if GNULIB_TEST_MODFF
 SIGNATURE_CHECK (GNULIB_NAMESPACE::modff, float, (float, float *));
 
 #if GNULIB_TEST_MODFF
 SIGNATURE_CHECK (GNULIB_NAMESPACE::modff, float, (float, float *));