From b17d7ac7df62c7c7f56fe857ed28151d8b0e4e28 Mon Sep 17 00:00:00 2001
From: Bruno Haible <bruno@clisp.org>
Date: Sat, 26 Jan 2008 15:17:58 +0100
Subject: Rename isnan, applicable to 'double' only, to isnand.

---
 m4/isnand.m4 | 137 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 m4/isnand.m4

(limited to 'm4/isnand.m4')

diff --git a/m4/isnand.m4 b/m4/isnand.m4
new file mode 100644
index 0000000000..4f747eae0d
--- /dev/null
+++ b/m4/isnand.m4
@@ -0,0 +1,137 @@
+# isnand.m4 serial 1
+dnl Copyright (C) 2007-2008 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.
+
+dnl Check how to get or define isnand() without linking with libm.
+
+AC_DEFUN([gl_FUNC_ISNAND_NO_LIBM],
+[
+  AC_CACHE_CHECK([whether isnan(double) can be used without linking with libm],
+    [gl_cv_func_isnand_no_libm],
+    [
+      AC_TRY_LINK([#include <math.h>
+                   double x;],
+                  [return isnan (x);],
+        [gl_cv_func_isnand_no_libm=yes],
+        [gl_cv_func_isnand_no_libm=no])
+    ])
+  if test $gl_cv_func_isnand_no_libm = yes; then
+    AC_DEFINE([HAVE_ISNAND_IN_LIBC], 1,
+      [Define if the isnan(double) function is available in libc.])
+  else
+    AC_LIBOBJ([isnand])
+    gl_DOUBLE_EXPONENT_LOCATION
+  fi
+])
+
+AC_DEFUN([gl_DOUBLE_EXPONENT_LOCATION],
+[
+  AC_CACHE_CHECK([where to find the exponent in a 'double'],
+    [gl_cv_cc_double_expbit0],
+    [
+      AC_TRY_RUN([
+#include <float.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#define NWORDS \
+  ((sizeof (double) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
+typedef union { double value; unsigned int word[NWORDS]; } memory_double;
+static unsigned int ored_words[NWORDS];
+static unsigned int anded_words[NWORDS];
+static void add_to_ored_words (double x)
+{
+  memory_double m;
+  size_t i;
+  /* Clear it first, in case sizeof (double) < sizeof (memory_double).  */
+  memset (&m, 0, sizeof (memory_double));
+  m.value = x;
+  for (i = 0; i < NWORDS; i++)
+    {
+      ored_words[i] |= m.word[i];
+      anded_words[i] &= m.word[i];
+    }
+}
+int main ()
+{
+  size_t j;
+  FILE *fp = fopen ("conftest.out", "w");
+  if (fp == NULL)
+    return 1;
+  for (j = 0; j < NWORDS; j++)
+    anded_words[j] = ~ (unsigned int) 0;
+  add_to_ored_words (0.25);
+  add_to_ored_words (0.5);
+  add_to_ored_words (1.0);
+  add_to_ored_words (2.0);
+  add_to_ored_words (4.0);
+  /* Remove bits that are common (e.g. if representation of the first mantissa
+     bit is explicit).  */
+  for (j = 0; j < NWORDS; j++)
+    ored_words[j] &= ~anded_words[j];
+  /* Now find the nonzero word.  */
+  for (j = 0; j < NWORDS; j++)
+    if (ored_words[j] != 0)
+      break;
+  if (j < NWORDS)
+    {
+      size_t i;
+      for (i = j + 1; i < NWORDS; i++)
+        if (ored_words[i] != 0)
+          {
+            fprintf (fp, "unknown");
+            return (fclose (fp) != 0);
+          }
+      for (i = 0; ; i++)
+        if ((ored_words[j] >> i) & 1)
+          {
+            fprintf (fp, "word %d bit %d", (int) j, (int) i);
+            return (fclose (fp) != 0);
+          }
+    }
+  fprintf (fp, "unknown");
+  return (fclose (fp) != 0);
+}
+        ],
+        [gl_cv_cc_double_expbit0=`cat conftest.out`],
+        [gl_cv_cc_double_expbit0="unknown"],
+        [
+          dnl On ARM, there are two 'double' floating-point formats, used by
+          dnl different sets of instructions: The older FPA instructions assume
+          dnl that they are stored in big-endian word order, while the words
+          dnl (like integer types) are stored in little-endian byte order.
+          dnl The newer VFP instructions assume little-endian order consistenly.
+          AC_EGREP_CPP([mixed_endianness], [
+#if defined arm || defined __arm || defined __arm__
+  mixed_endianness
+#endif
+            ],
+            [gl_cv_cc_double_expbit0="unknown"],
+            [
+              pushdef([AC_MSG_CHECKING],[:])dnl
+              pushdef([AC_MSG_RESULT],[:])dnl
+              pushdef([AC_MSG_RESULT_UNQUOTED],[:])dnl
+              AC_C_BIGENDIAN(
+                [gl_cv_cc_double_expbit0="word 0 bit 20"],
+                [gl_cv_cc_double_expbit0="word 1 bit 20"],
+                [gl_cv_cc_double_expbit0="unknown"])
+              popdef([AC_MSG_RESULT_UNQUOTED])dnl
+              popdef([AC_MSG_RESULT])dnl
+              popdef([AC_MSG_CHECKING])dnl
+            ])
+        ])
+      rm -f conftest.out
+    ])
+  case "$gl_cv_cc_double_expbit0" in
+    word*bit*)
+      word=`echo "$gl_cv_cc_double_expbit0" | sed -e 's/word //' -e 's/ bit.*//'`
+      bit=`echo "$gl_cv_cc_double_expbit0" | sed -e 's/word.*bit //'`
+      AC_DEFINE_UNQUOTED([DBL_EXPBIT0_WORD], [$word],
+        [Define as the word index where to find the exponent of 'double'.])
+      AC_DEFINE_UNQUOTED([DBL_EXPBIT0_BIT], [$bit],
+        [Define as the bit index in the word where to find bit 0 of the exponent of 'double'.])
+      ;;
+  esac
+])
-- 
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