common/m4/gst-arch.m4: Add GST_UNALIGNED_ACCESS() macro that checks if we can access unaligned memory.

Original commit message from CVS:
* common/m4/gst-arch.m4: Add GST_UNALIGNED_ACCESS() macro that
checks if we can access unaligned memory.
* configure.ac: Use it.

1 files changed, 26 insertions, 0 deletions

diff --git a/m4/gst-arch.m4 b/m4/gst-arch.m4
index 33ea993..13b18e4 100644
--- a/m4/gst-arch.m4
+++ b/m4/gst-arch.m4
@@ -81,3 +81,29 @@ AM_CONDITIONAL(HAVE_CPU_X86_64,     test "x$HAVE_CPU_X86_64" = "xyes")
 AM_CONDITIONAL(HAVE_LIBMMX,         test "x$USE_LIBMMX" = "xyes")
 
 ])
+
+AC_DEFUN([GST_UNALIGNED_ACCESS], [
+  AC_MSG_CHECKING([if unaligned memory access works correctly])
+  if test x"$as_cv_unaligned_access" = x ; then
+    AC_TRY_RUN([
+int main(int argc, char **argv)
+{
+  char array[] = "ABCDEFGH";
+  unsigned int iarray[2];
+  memcpy(iarray,array,8);
+#define GET(x) (*(unsigned int *)((char *)iarray + (x)))
+  if(GET(0) != 0x41424344 && GET(0) != 0x44434241) return 1;
+  if(GET(1) != 0x42434445 && GET(1) != 0x45444342) return 1;
+  if(GET(2) != 0x43444546 && GET(2) != 0x46454443) return 1;
+  if(GET(3) != 0x44454647 && GET(3) != 0x47464544) return 1;
+  return 0;
+}
+    ], as_cv_unaligned_access="yes", as_cv_unaligned_access="no")
+  fi
+  AC_MSG_RESULT($as_cv_unaligned_access)
+  if test "$gst_unaligned_access" = "yes"; then
+    AC_DEFINE_UNQUOTED(HAVE_UNALIGNED_ACCESS, 1,
+      [defined if unaligned memory access works correctly])
+  fi
+])
+