X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fmemcmp.m4;h=91b3dd3152ad3c7c947a2d658e6b944e5f2a34a8;hb=118c7c3af6b537e01580f3ddd29262cdc7ee17b9;hp=e76aeda87079989ffeae71c51542904155854428;hpb=409d8f2d902cc6e12e40b08200f5dac27d0e98cb;p=gnulib.git

diff --git a/m4/memcmp.m4 b/m4/memcmp.m4
index e76aeda87..91b3dd315 100644
--- a/m4/memcmp.m4
+++ b/m4/memcmp.m4
@@ -1,13 +1,48 @@
-#serial 1
+#serial 5
+
+dnl A replacement for autoconf's AC_FUNC_MEMCMP that detects
+dnl the losing memcmp on some x86 Next systems.
+AC_DEFUN(jm_AC_FUNC_MEMCMP,
+[AC_CACHE_CHECK([for working memcmp], jm_cv_func_memcmp_working,
+[AC_TRY_RUN(
+[int
+main ()
+{
+  /* Some versions of memcmp are not 8-bit clean.  */
+  char c0 = 0x40, c1 = 0x80, c2 = 0x81;
+  if (memcmp(&c0, &c2, 1) >= 0 || memcmp(&c1, &c2, 1) >= 0)
+    exit (1);
+
+  /* The Next x86 OpenStep bug shows up only when comparing 16 bytes
+     or more and with at least one buffer not starting on a 4-byte boundary.
+     William Lewis provided this test program.   */
+  {
+    char foo[21];
+    char bar[21];
+    int i;
+    for (i = 0; i < 4; i++)
+      {
+	char *a = foo + i;
+	char *b = bar + i;
+	strcpy (a, "--------01111111");
+	strcpy (b, "--------10000000");
+	if (memcmp (a, b, 16) >= 0)
+	  exit (1);
+      }
+    exit (0);
+  }
+}],
+   jm_cv_func_memcmp_working=yes,
+   jm_cv_func_memcmp_working=no,
+   jm_cv_func_memcmp_working=no)])
+test $jm_cv_func_memcmp_working = no \
+  && AC_LIBOBJ(memcmp)
+])
 
-dnl If you use this macro in a package, you should
-dnl add the following two lines to acconfig.h:
-dnl   /* Define to rpl_memcmp if the replacement function should be used.  */
-dnl   #undef memcmp
-dnl
 AC_DEFUN(jm_FUNC_MEMCMP,
-[AC_REQUIRE([AC_FUNC_MEMCMP])dnl
- if test $ac_cv_func_memcmp_clean = no; then
-   AC_DEFINE_UNQUOTED(memcmp, rpl_memcmp)
+[AC_REQUIRE([jm_AC_FUNC_MEMCMP])dnl
+ if test $jm_cv_func_memcmp_working = no; then
+   AC_DEFINE_UNQUOTED(memcmp, rpl_memcmp,
+     [Define to rpl_memcmp if the replacement function should be used.])
  fi
 ])