patch to split DSD decoder into separate decoders for DSF en DFF. Move common

functions to new dsdlib. Update user doc.

src/decoder/dsdlib.c

@@ -0,0 +1,112 @@
+/*
+ * Copyright (C) 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.
+ */
+
+/* \file
+ *
+ * This file contains functions used by the DSF and DSDIFF decoders.
+ *
+ */
+
+#include "config.h"
+#include "dsf_decoder_plugin.h"
+#include "decoder_api.h"
+#include "util/bit_reverse.h"
+#include "dsdlib.h"
+#include "dsdiff_decoder_plugin.h"
+
+#include <unistd.h>
+#include <stdio.h> /* for SEEK_SET, SEEK_CUR */
+
+bool
+dsdlib_id_equals(const struct dsdlib_id *id, const char *s)
+{
+	assert(id != NULL);
+	assert(s != NULL);
+	assert(strlen(s) == sizeof(id->value));
+
+	return memcmp(id->value, s, sizeof(id->value)) == 0;
+}
+
+bool
+dsdlib_read(struct decoder *decoder, struct input_stream *is,
+	    void *data, size_t length)
+{
+	size_t nbytes = decoder_read(decoder, is, data, length);
+	return nbytes == length;
+}
+
+/**
+ * Skip the #input_stream to the specified offset.
+ */
+bool
+dsdlib_skip_to(struct decoder *decoder, struct input_stream *is,
+	       goffset offset)
+{
+	if (is->seekable)
+		return input_stream_seek(is, offset, SEEK_SET, NULL);
+
+	if (is->offset > offset)
+		return false;
+
+	char buffer[8192];
+	while (is->offset < offset) {
+		size_t length = sizeof(buffer);
+		if (offset - is->offset < (goffset)length)
+			length = offset - is->offset;
+
+		size_t nbytes = decoder_read(decoder, is, buffer, length);
+		if (nbytes == 0)
+			return false;
+	}
+
+	assert(is->offset == offset);
+	return true;
+}
+
+/**
+ * Skip some bytes from the #input_stream.
+ */
+bool
+dsdlib_skip(struct decoder *decoder, struct input_stream *is,
+	    goffset delta)
+{
+	assert(delta >= 0);
+
+	if (delta == 0)
+		return true;
+
+	if (is->seekable)
+		return input_stream_seek(is, delta, SEEK_CUR, NULL);
+
+	char buffer[8192];
+	while (delta > 0) {
+		size_t length = sizeof(buffer);
+		if ((goffset)length > delta)
+			length = delta;
+
+		size_t nbytes = decoder_read(decoder, is, buffer, length);
+		if (nbytes == 0)
+			return false;
+
+		delta -= nbytes;
+	}
+
+	return true;
+}
+