168 lines
3.7 KiB
C
168 lines
3.7 KiB
C
/*
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* Copyright (C) 2003-2010 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "config.h"
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#include "decoder_buffer.h"
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#include "decoder_api.h"
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#include <glib.h>
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#include <assert.h>
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struct decoder_buffer {
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struct decoder *decoder;
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struct input_stream *is;
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/** the allocated size of the buffer */
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size_t size;
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/** the current length of the buffer */
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size_t length;
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/** number of bytes already consumed at the beginning of the
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buffer */
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size_t consumed;
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/** the actual buffer (dynamic size) */
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unsigned char data[sizeof(size_t)];
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};
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struct decoder_buffer *
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decoder_buffer_new(struct decoder *decoder, struct input_stream *is,
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size_t size)
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{
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struct decoder_buffer *buffer =
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g_malloc(sizeof(*buffer) - sizeof(buffer->data) + size);
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assert(is != NULL);
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assert(size > 0);
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buffer->decoder = decoder;
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buffer->is = is;
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buffer->size = size;
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buffer->length = 0;
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buffer->consumed = 0;
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return buffer;
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}
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void
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decoder_buffer_free(struct decoder_buffer *buffer)
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{
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assert(buffer != NULL);
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g_free(buffer);
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}
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bool
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decoder_buffer_is_empty(const struct decoder_buffer *buffer)
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{
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return buffer->consumed == buffer->length;
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}
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bool
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decoder_buffer_is_full(const struct decoder_buffer *buffer)
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{
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return buffer->consumed == 0 && buffer->length == buffer->size;
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}
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static void
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decoder_buffer_shift(struct decoder_buffer *buffer)
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{
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assert(buffer->consumed > 0);
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buffer->length -= buffer->consumed;
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memmove(buffer->data, buffer->data + buffer->consumed, buffer->length);
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buffer->consumed = 0;
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}
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bool
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decoder_buffer_fill(struct decoder_buffer *buffer)
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{
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size_t nbytes;
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if (buffer->consumed > 0)
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decoder_buffer_shift(buffer);
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if (buffer->length >= buffer->size)
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/* buffer is full */
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return false;
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nbytes = decoder_read(buffer->decoder, buffer->is,
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buffer->data + buffer->length,
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buffer->size - buffer->length);
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if (nbytes == 0)
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/* end of file, I/O error or decoder command
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received */
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return false;
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buffer->length += nbytes;
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assert(buffer->length <= buffer->size);
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return true;
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}
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const void *
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decoder_buffer_read(const struct decoder_buffer *buffer, size_t *length_r)
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{
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if (buffer->consumed >= buffer->length)
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/* buffer is empty */
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return NULL;
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*length_r = buffer->length - buffer->consumed;
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return buffer->data + buffer->consumed;
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}
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void
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decoder_buffer_consume(struct decoder_buffer *buffer, size_t nbytes)
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{
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/* just move the "consumed" pointer - decoder_buffer_shift()
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will do the real work later (called by
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decoder_buffer_fill()) */
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buffer->consumed += nbytes;
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assert(buffer->consumed <= buffer->length);
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}
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bool
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decoder_buffer_skip(struct decoder_buffer *buffer, size_t nbytes)
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{
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size_t length;
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const void *data;
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bool success;
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/* this could probably be optimized by seeking */
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while (true) {
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data = decoder_buffer_read(buffer, &length);
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if (data != NULL) {
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if (length > nbytes)
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length = nbytes;
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decoder_buffer_consume(buffer, length);
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nbytes -= length;
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if (nbytes == 0)
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return true;
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}
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success = decoder_buffer_fill(buffer);
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if (!success)
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return false;
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}
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}
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