audio_format: support packed 24 bit samples

1 files changed, 93 insertions, 0 deletions

diff --git a/src/pcm_pack.c b/src/pcm_pack.c
new file mode 100644
index 00000000..9af0ab1e
--- /dev/null
+++ b/src/pcm_pack.c
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2003-2010 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.
+ */
+
+#include "pcm_pack.h"
+
+#include <glib.h>
+
+static void
+pack_sample(uint8_t *dest, const int32_t *src0, bool reverse_endian)
+{
+	const uint8_t *src = (const uint8_t *)src0;
+
+	if ((G_BYTE_ORDER == G_BIG_ENDIAN) != reverse_endian)
+		++src;
+
+	*dest++ = *src++;
+	*dest++ = *src++;
+	*dest++ = *src++;
+}
+
+void
+pcm_pack_24(uint8_t *dest, const int32_t *src, unsigned num_samples,
+	    bool reverse_endian)
+{
+	/* duplicate loop to help the compiler's optimizer (constant
+	   parameter to the pack_sample() inline function) */
+
+	if (G_LIKELY(!reverse_endian)) {
+		while (num_samples-- > 0) {
+			pack_sample(dest, src++, false);
+			dest += 3;
+		}
+	} else {
+		while (num_samples-- > 0) {
+			pack_sample(dest, src++, true);
+			dest += 3;
+		}
+	}
+}
+
+static void
+unpack_sample(int32_t *dest0, const uint8_t *src, bool reverse_endian)
+{
+	uint8_t *dest = (uint8_t *)dest0;
+
+	if ((G_BYTE_ORDER == G_BIG_ENDIAN) != reverse_endian)
+		/* extend the sign bit to the most fourth byte */
+		*dest++ = *src & 0x80 ? 0xff : 0x00;
+
+	*dest++ = *src++;
+	*dest++ = *src++;
+	*dest++ = *src;
+
+	if ((G_BYTE_ORDER == G_LITTLE_ENDIAN) != reverse_endian)
+		/* extend the sign bit to the most fourth byte */
+		*dest++ = *src & 0x80 ? 0xff : 0x00;
+}
+
+void
+pcm_unpack_24(int32_t *dest, const uint8_t *src, unsigned num_samples,
+	      bool reverse_endian)
+{
+	/* duplicate loop to help the compiler's optimizer (constant
+	   parameter to the unpack_sample() inline function) */
+
+	if (G_LIKELY(!reverse_endian)) {
+		while (num_samples-- > 0) {
+			unpack_sample(dest++, src, false);
+			src += 3;
+		}
+	} else {
+		while (num_samples-- > 0) {
+			unpack_sample(dest++, src, true);
+			src += 3;
+		}
+	}
+}