dsd2pcm: move the bit reversing code to a generic library

Instead of doing run-time initialisation, use a constant lookup table.

src/util/bit_reverse.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2003-2012 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * 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 of the License, 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.
+ */
+
+#ifndef MPD_BIT_REVERSE_H
+#define MPD_BIT_REVERSE_H
+
+#include <glib.h>
+#include <stdint.h>
+
+extern const uint8_t bit_reverse_table[256];
+
+G_GNUC_CONST
+static inline uint8_t
+bit_reverse(uint8_t x)
+{
+	return bit_reverse_table[x];
+}
+
+#endif