Import xz 5.2.2 (as of svn r86089)

m4/tuklib_integer.m4

@@ -0,0 +1,74 @@
+#
+# SYNOPSIS
+#
+#   TUKLIB_INTEGER
+#
+# DESCRIPTION
+#
+#   Checks for tuklib_integer.h:
+#     - Endianness
+#     - Does operating system provide byte swapping macros
+#     - Does the hardware support fast unaligned access to 16-bit
+#       and 32-bit integers
+#
+# COPYING
+#
+#   Author: Lasse Collin
+#
+#   This file has been put into the public domain.
+#   You can do whatever you want with this file.
+#
+
+AC_DEFUN_ONCE([TUKLIB_INTEGER], [
+AC_REQUIRE([TUKLIB_COMMON])
+AC_REQUIRE([AC_C_BIGENDIAN])
+AC_CHECK_HEADERS([byteswap.h sys/endian.h sys/byteorder.h], [break])
+
+# Even if we have byteswap.h, we may lack the specific macros/functions.
+if test x$ac_cv_header_byteswap_h = xyes ; then
+	m4_foreach([FUNC], [bswap_16,bswap_32,bswap_64], [
+		AC_MSG_CHECKING([if FUNC is available])
+		AC_LINK_IFELSE([AC_LANG_SOURCE([
+#include <byteswap.h>
+int
+main(void)
+{
+	FUNC[](42);
+	return 0;
+}
+		])], [
+			AC_DEFINE(HAVE_[]m4_toupper(FUNC), [1],
+					[Define to 1 if] FUNC [is available.])
+			AC_MSG_RESULT([yes])
+		], [AC_MSG_RESULT([no])])
+
+	])dnl
+fi
+
+AC_MSG_CHECKING([if unaligned memory access should be used])
+AC_ARG_ENABLE([unaligned-access], AS_HELP_STRING([--enable-unaligned-access],
+		[Enable if the system supports *fast* unaligned memory access
+		with 16-bit and 32-bit integers. By default, this is enabled
+		only on x86, x86_64, and big endian PowerPC.]),
+	[], [enable_unaligned_access=auto])
+if test "x$enable_unaligned_access" = xauto ; then
+	# TODO: There may be other architectures, on which unaligned access
+	# is OK.
+	case $host_cpu in
+		i?86|x86_64|powerpc|powerpc64)
+			enable_unaligned_access=yes
+			;;
+		*)
+			enable_unaligned_access=no
+			;;
+	esac
+fi
+if test "x$enable_unaligned_access" = xyes ; then
+	AC_DEFINE([TUKLIB_FAST_UNALIGNED_ACCESS], [1], [Define to 1 if
+		the system supports fast unaligned access to 16-bit and
+		32-bit integers.])
+	AC_MSG_RESULT([yes])
+else
+	AC_MSG_RESULT([no])
+fi
+])dnl