rint: Support for MSVC.

* lib/math.in.h (rint): New declaration.
* lib/rint.c: New file.
* m4/rint.m4: New file.
* m4/math_h.m4 (gl_MATH_H): Test whether rint is declared.
(gl_MATH_H_DEFAULTS): Initialize GNULIB_RINT, HAVE_RINT.
* modules/math (Makefile.am): Substitute GNULIB_RINT, HAVE_RINT.
* modules/rint (Description): Fix.
(Files): Add lib/rint.c, m4/rint.m4.
(Depends-on): Add math.
(configure.ac): Invoke gl_FUNC_RINT, AC_LIBOBJ,
gl_MATH_MODULE_INDICATOR.
* tests/test-math-c++.cc: Check the declaration of rint.
* modules/math-c++-tests (Makefile.am): Link test-math-c++ against
$(RINT_LIBM). Needed on IRIX 6.5 with cc.
* doc/posix-functions/rint.texi: Mention the replacement provided by
the module.

10 files changed, 183 insertions, 9 deletions

diff --git a/ChangeLog b/ChangeLog
index f3c83b1d39..449994988f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,23 @@
 2011-10-09  Bruno Haible  <bruno@clisp.org>
 
+	rint: Support for MSVC.
+	* lib/math.in.h (rint): New declaration.
+	* lib/rint.c: New file.
+	* m4/rint.m4: New file.
+	* m4/math_h.m4 (gl_MATH_H): Test whether rint is declared.
+	(gl_MATH_H_DEFAULTS): Initialize GNULIB_RINT, HAVE_RINT.
+	* modules/math (Makefile.am): Substitute GNULIB_RINT, HAVE_RINT.
+	* modules/rint (Description): Fix.
+	(Files): Add lib/rint.c, m4/rint.m4.
+	(Depends-on): Add math.
+	(configure.ac): Invoke gl_FUNC_RINT, AC_LIBOBJ,
+	gl_MATH_MODULE_INDICATOR.
+	* tests/test-math-c++.cc: Check the declaration of rint.
+	* modules/math-c++-tests (Makefile.am): Link test-math-c++ against
+	$(RINT_LIBM). Needed on IRIX 6.5 with cc.
+	* doc/posix-functions/rint.texi: Mention the replacement provided by
+	the module.
+
 	rint tests: More tests.
 	* tests/test-rint.c: Include <float.h>, <stdio.h>, isnand-nolibm.h,
 	minus-zero.h, infinity.h, nan.h.
diff --git a/doc/posix-functions/rint.texi b/doc/posix-functions/rint.texi
index 271b9f82e7..996895c06c 100644
--- a/doc/posix-functions/rint.texi
+++ b/doc/posix-functions/rint.texi
@@ -8,11 +8,11 @@ Gnulib module: rint
 
 Portability problems fixed by Gnulib:
 @itemize
+@item
+This function is missing on some platforms:
+MSVC 9.
 @end itemize
 
 Portability problems not fixed by Gnulib:
 @itemize
-@item
-This function is missing on some platforms:
-MSVC 9.
 @end itemize
diff --git a/lib/math.in.h b/lib/math.in.h
index cc8060e24b..7269345b7f 100644
--- a/lib/math.in.h
+++ b/lib/math.in.h
@@ -712,6 +712,21 @@ _GL_WARN_ON_USE (powf, "powf is unportable - "
 #endif
 
 
+#if @GNULIB_RINT@
+# if !@HAVE_RINT@
+_GL_FUNCDECL_SYS (rint, double, (double x));
+# endif
+_GL_CXXALIAS_SYS (rint, double, (double x));
+_GL_CXXALIASWARN (rint);
+#elif defined GNULIB_POSIXCHECK
+# undef rint
+# if HAVE_RAW_DECL_RINT
+_GL_WARN_ON_USE (rint, "rint is unportable - "
+                 "use gnulib module rint for portability");
+# endif
+#endif
+
+
 #if @GNULIB_ROUNDF@
 # if @REPLACE_ROUNDF@
 #  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
diff --git a/lib/rint.c b/lib/rint.c
new file mode 100644
index 0000000000..4ba3fe5547
--- /dev/null
+++ b/lib/rint.c
@@ -0,0 +1,110 @@
+/* Round according to the current rounding mode.
+   Copyright (C) 2007, 2010-2011 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 2, 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <math.h>
+
+#include <float.h>
+#include <stdlib.h>
+
+#undef MIN
+
+#ifdef USE_LONG_DOUBLE
+# define RINT rintl
+# define DOUBLE long double
+# define MANT_DIG LDBL_MANT_DIG
+# define MIN LDBL_MIN
+# define L_(literal) literal##L
+#elif ! defined USE_FLOAT
+# define RINT rint
+# define DOUBLE double
+# define MANT_DIG DBL_MANT_DIG
+# define MIN DBL_MIN
+# define L_(literal) literal
+#else /* defined USE_FLOAT */
+# define RINT rintf
+# define DOUBLE float
+# define MANT_DIG FLT_MANT_DIG
+# define MIN FLT_MIN
+# define L_(literal) literal##f
+#endif
+
+/* -0.0.  See minus-zero.h.  */
+#if defined __hpux || defined __sgi || defined __ICC
+# define MINUS_ZERO (-MIN * MIN)
+#else
+# define MINUS_ZERO L_(-0.0)
+#endif
+
+DOUBLE
+RINT (DOUBLE x)
+{
+  /* 2^(MANT_DIG-1).  */
+  static const DOUBLE TWO_MANT_DIG =
+    /* Assume MANT_DIG <= 5 * 31.
+       Use the identity
+       n = floor(n/5) + floor((n+1)/5) + ... + floor((n+4)/5).  */
+    (DOUBLE) (1U << ((MANT_DIG - 1) / 5))
+    * (DOUBLE) (1U << ((MANT_DIG - 1 + 1) / 5))
+    * (DOUBLE) (1U << ((MANT_DIG - 1 + 2) / 5))
+    * (DOUBLE) (1U << ((MANT_DIG - 1 + 3) / 5))
+    * (DOUBLE) (1U << ((MANT_DIG - 1 + 4) / 5));
+
+  /* The use of 'volatile' guarantees that excess precision bits are dropped at
+     each addition step and before the following comparison at the caller's
+     site.  It is necessary on x86 systems where double-floats are not IEEE
+     compliant by default, to avoid that the results become platform and
+     compiler option dependent.  'volatile' is a portable alternative to gcc's
+     -ffloat-store option.  */
+  volatile DOUBLE z = x;
+
+  /* Consider the current rounding mode, cf.
+     <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/float.h.html>.
+     This implementation supports only rounds-to-nearest.  */
+  if (FLT_ROUNDS != 1)
+    abort ();
+
+  if (z > L_(0.0))
+    {
+      /* Avoid rounding error for x = 0.5 - 2^(-MANT_DIG-1).  */
+      if (z < L_(0.5))
+        z = L_(0.0);
+      /* Avoid rounding errors for values near 2^k, where k >= MANT_DIG-1.  */
+      else if (z < TWO_MANT_DIG)
+        {
+          /* Round to the next integer.  */
+          z += TWO_MANT_DIG;
+          z -= TWO_MANT_DIG;
+        }
+    }
+  else if (z < L_(0.0))
+    {
+      /* Avoid rounding error for x = -(0.5 - 2^(-MANT_DIG-1)).  */
+      if (z > - L_(0.5))
+        z = MINUS_ZERO;
+      /* Avoid rounding errors for values near -2^k, where k >= MANT_DIG-1.  */
+      else if (z > -TWO_MANT_DIG)
+        {
+          /* Round to the next integer.  */
+          z -= TWO_MANT_DIG;
+          z += TWO_MANT_DIG;
+        }
+    }
+  return z;
+}
diff --git a/m4/math_h.m4 b/m4/math_h.m4
index bcc6a3f96e..c3a27e0a7b 100644
--- a/m4/math_h.m4
+++ b/m4/math_h.m4
@@ -1,4 +1,4 @@
-# math_h.m4 serial 50
+# math_h.m4 serial 51
 dnl Copyright (C) 2007-2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -43,7 +43,7 @@ AC_DEFUN([gl_MATH_H],
      ceilf ceill copysign copysignf copysignl cosf cosl coshf
      expf expl fabsf floorf floorl fmodf frexpf frexpl
      ldexpf ldexpl logb logf logl log10f modff powf
-     round roundf roundl sinf sinl sinhf sqrtf sqrtl
+     rint round roundf roundl sinf sinl sinhf sqrtf sqrtl
      tanf tanl tanhf trunc truncf truncl])
 ])
 
@@ -98,6 +98,7 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   GNULIB_LOG10F=0;    AC_SUBST([GNULIB_LOG10F])
   GNULIB_MODFF=0;     AC_SUBST([GNULIB_MODFF])
   GNULIB_POWF=0;      AC_SUBST([GNULIB_POWF])
+  GNULIB_RINT=0;      AC_SUBST([GNULIB_RINT])
   GNULIB_ROUND=0;     AC_SUBST([GNULIB_ROUND])
   GNULIB_ROUNDF=0;    AC_SUBST([GNULIB_ROUNDF])
   GNULIB_ROUNDL=0;    AC_SUBST([GNULIB_ROUNDL])
@@ -141,6 +142,7 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   HAVE_LOG10F=1;               AC_SUBST([HAVE_LOG10F])
   HAVE_MODFF=1;                AC_SUBST([HAVE_MODFF])
   HAVE_POWF=1;                 AC_SUBST([HAVE_POWF])
+  HAVE_RINT=1;                 AC_SUBST([HAVE_RINT])
   HAVE_SINF=1;                 AC_SUBST([HAVE_SINF])
   HAVE_SINL=1;                 AC_SUBST([HAVE_SINL])
   HAVE_SINHF=1;                AC_SUBST([HAVE_SINHF])
diff --git a/m4/rint.m4 b/m4/rint.m4
new file mode 100644
index 0000000000..9d7335d28a
--- /dev/null
+++ b/m4/rint.m4
@@ -0,0 +1,17 @@
+# rint.m4 serial 1
+dnl Copyright (C) 2011 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_RINT],
+[
+  dnl Determine RINT_LIBM.
+  gl_MATHFUNC([rint], [double], [(double)])
+  if test $gl_cv_func_rint_no_libm = no \
+     && test $gl_cv_func_rint_in_libm = no; then
+    HAVE_RINT=0
+    RINT_LIBM=
+  fi
+  AC_SUBST([RINT_LIBM])
+])
diff --git a/modules/math b/modules/math
index 0e0f4eae29..57d5798860 100644
--- a/modules/math
+++ b/modules/math
@@ -68,6 +68,7 @@ math.h: math.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(
 	      -e 's/@''GNULIB_LOG10F''@/$(GNULIB_LOG10F)/g' \
 	      -e 's/@''GNULIB_MODFF''@/$(GNULIB_MODFF)/g' \
 	      -e 's/@''GNULIB_POWF''@/$(GNULIB_POWF)/g' \
+	      -e 's/@''GNULIB_RINT''@/$(GNULIB_RINT)/g' \
 	      -e 's/@''GNULIB_ROUND''@/$(GNULIB_ROUND)/g' \
 	      -e 's/@''GNULIB_ROUNDF''@/$(GNULIB_ROUNDF)/g' \
 	      -e 's/@''GNULIB_ROUNDL''@/$(GNULIB_ROUNDL)/g' \
@@ -111,6 +112,7 @@ math.h: math.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(
 	      -e 's|@''HAVE_LOG10F''@|$(HAVE_LOG10F)|g' \
 	      -e 's|@''HAVE_MODFF''@|$(HAVE_MODFF)|g' \
 	      -e 's|@''HAVE_POWF''@|$(HAVE_POWF)|g' \
+	      -e 's|@''HAVE_RINT''@|$(HAVE_RINT)|g' \
 	      -e 's|@''HAVE_SINF''@|$(HAVE_SINF)|g' \
 	      -e 's|@''HAVE_SINL''@|$(HAVE_SINL)|g' \
 	      -e 's|@''HAVE_SINHF''@|$(HAVE_SINHF)|g' \
diff --git a/modules/math-c++-tests b/modules/math-c++-tests
index 6e2d003437..35f37b8420 100644
--- a/modules/math-c++-tests
+++ b/modules/math-c++-tests
@@ -16,5 +16,6 @@ if ANSICXX
 TESTS += test-math-c++
 check_PROGRAMS += test-math-c++
 test_math_c___SOURCES = test-math-c++.cc test-math-c++2.cc
-test_math_c___LDADD = $(LDADD) $(COPYSIGNL_LIBM)
+# These link dependencies are needed on IRIX 6.5 with cc.
+test_math_c___LDADD = $(LDADD) $(COPYSIGNL_LIBM) $(RINT_LIBM)
 endif
diff --git a/modules/rint b/modules/rint
index 276c9263f9..08cdc4ca47 100644
--- a/modules/rint
+++ b/modules/rint
@@ -1,13 +1,20 @@
 Description:
-rint() function: round to nearest integer.
+rint() function: round according to the current rounding mode.
 
 Files:
+lib/rint.c
+m4/rint.m4
 m4/mathfunc.m4
 
 Depends-on:
+math
 
 configure.ac:
-gl_MATHFUNC([rint], [double], [(double)])
+gl_FUNC_RINT
+if test $HAVE_RINT = 0; then
+  AC_LIBOBJ([rint])
+fi
+gl_MATH_MODULE_INDICATOR([rint])
 
 Makefile.am:
 
diff --git a/tests/test-math-c++.cc b/tests/test-math-c++.cc
index 371249246e..95be24f605 100644
--- a/tests/test-math-c++.cc
+++ b/tests/test-math-c++.cc
@@ -104,7 +104,9 @@ SIGNATURE_CHECK (GNULIB_NAMESPACE::powf, float, (float, float));
 #endif
 //SIGNATURE_CHECK (GNULIB_NAMESPACE::pow, double, (double, double));
 //SIGNATURE_CHECK (GNULIB_NAMESPACE::remainder, double, (double, double));
-//SIGNATURE_CHECK (GNULIB_NAMESPACE::rint, double, (double));
+#if GNULIB_TEST_RINT
+SIGNATURE_CHECK (GNULIB_NAMESPACE::rint, double, (double));
+#endif
 #if GNULIB_TEST_SINF
 SIGNATURE_CHECK (GNULIB_NAMESPACE::sinf, float, (float));
 #endif