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-rw-r--r--src/decoder/DecoderBuffer.cxx178
1 files changed, 178 insertions, 0 deletions
diff --git a/src/decoder/DecoderBuffer.cxx b/src/decoder/DecoderBuffer.cxx
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+++ b/src/decoder/DecoderBuffer.cxx
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+/*
+ * Copyright (C) 2003-2014 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 "config.h"
+#include "DecoderBuffer.hxx"
+#include "DecoderAPI.hxx"
+#include "util/ConstBuffer.hxx"
+#include "util/VarSize.hxx"
+
+#include <assert.h>
+#include <string.h>
+#include <stdlib.h>
+
+struct DecoderBuffer {
+ Decoder *decoder;
+ InputStream *is;
+
+ /** the allocated size of the buffer */
+ size_t size;
+
+ /** the current length of the buffer */
+ size_t length;
+
+ /** number of bytes already consumed at the beginning of the
+ buffer */
+ size_t consumed;
+
+ /** the actual buffer (dynamic size) */
+ unsigned char data[sizeof(size_t)];
+
+ DecoderBuffer(Decoder *_decoder, InputStream &_is,
+ size_t _size)
+ :decoder(_decoder), is(&_is),
+ size(_size), length(0), consumed(0) {}
+};
+
+DecoderBuffer *
+decoder_buffer_new(Decoder *decoder, InputStream &is,
+ size_t size)
+{
+ assert(size > 0);
+
+ return NewVarSize<DecoderBuffer>(sizeof(DecoderBuffer::data),
+ size,
+ decoder, is, size);
+}
+
+void
+decoder_buffer_free(DecoderBuffer *buffer)
+{
+ assert(buffer != nullptr);
+
+ DeleteVarSize(buffer);
+}
+
+const InputStream &
+decoder_buffer_get_stream(const DecoderBuffer *buffer)
+{
+ return *buffer->is;
+}
+
+void
+decoder_buffer_clear(DecoderBuffer *buffer)
+{
+ buffer->length = buffer->consumed = 0;
+}
+
+static void
+decoder_buffer_shift(DecoderBuffer *buffer)
+{
+ assert(buffer->consumed > 0);
+
+ buffer->length -= buffer->consumed;
+ memmove(buffer->data, buffer->data + buffer->consumed, buffer->length);
+ buffer->consumed = 0;
+}
+
+bool
+decoder_buffer_fill(DecoderBuffer *buffer)
+{
+ size_t nbytes;
+
+ if (buffer->consumed > 0)
+ decoder_buffer_shift(buffer);
+
+ if (buffer->length >= buffer->size)
+ /* buffer is full */
+ return false;
+
+ nbytes = decoder_read(buffer->decoder, *buffer->is,
+ buffer->data + buffer->length,
+ buffer->size - buffer->length);
+ if (nbytes == 0)
+ /* end of file, I/O error or decoder command
+ received */
+ return false;
+
+ buffer->length += nbytes;
+ assert(buffer->length <= buffer->size);
+
+ return true;
+}
+
+static const void *
+decoder_buffer_head(const DecoderBuffer *buffer)
+{
+ return buffer->data + buffer->consumed;
+}
+
+size_t
+decoder_buffer_available(const DecoderBuffer *buffer)
+{
+ return buffer->length - buffer->consumed;
+}
+
+ConstBuffer<void>
+decoder_buffer_read(const DecoderBuffer *buffer)
+{
+ return {
+ decoder_buffer_head(buffer),
+ decoder_buffer_available(buffer),
+ };
+}
+
+ConstBuffer<void>
+decoder_buffer_need(DecoderBuffer *buffer, size_t min_size)
+{
+ while (true) {
+ const auto available = decoder_buffer_available(buffer);
+ if (available >= min_size)
+ return { decoder_buffer_head(buffer), available };
+
+ if (!decoder_buffer_fill(buffer))
+ return nullptr;
+ }
+}
+
+void
+decoder_buffer_consume(DecoderBuffer *buffer, size_t nbytes)
+{
+ /* just move the "consumed" pointer - decoder_buffer_shift()
+ will do the real work later (called by
+ decoder_buffer_fill()) */
+ buffer->consumed += nbytes;
+
+ assert(buffer->consumed <= buffer->length);
+}
+
+bool
+decoder_buffer_skip(DecoderBuffer *buffer, size_t nbytes)
+{
+ const size_t available = decoder_buffer_available(buffer);
+ if (available >= nbytes) {
+ decoder_buffer_consume(buffer, nbytes);
+ return true;
+ }
+
+ decoder_buffer_clear(buffer);
+ nbytes -= available;
+
+ return decoder_skip(buffer->decoder, *buffer->is, nbytes);
+}