diff options
| -rw-r--r-- | src/Makefile.am | 2 | ||||
| -rw-r--r-- | src/decoder_buffer.c | 139 | ||||
| -rw-r--r-- | src/decoder_buffer.h | 95 |
3 files changed, 236 insertions, 0 deletions
diff --git a/src/Makefile.am b/src/Makefile.am index 1fc01f000..700a82f41 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -63,6 +63,7 @@ mpd_headers = \ decoder_thread.h \ decoder_control.h \ decoder_plugin.h \ + decoder_buffer.h \ decoder_api.h \ decoder_internal.h \ directory.h \ @@ -166,6 +167,7 @@ mpd_SOURCES = \ dbUtils.c \ decoder_thread.c \ decoder_control.c \ + decoder_buffer.c \ decoder_api.c \ directory.c \ directory_save.c \ diff --git a/src/decoder_buffer.c b/src/decoder_buffer.c new file mode 100644 index 000000000..6d321df10 --- /dev/null +++ b/src/decoder_buffer.c @@ -0,0 +1,139 @@ +/* + * Copyright (C) 2003-2009 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include "decoder_buffer.h" +#include "decoder_api.h" + +#include <glib.h> + +#include <assert.h> + +struct decoder_buffer { + struct decoder *decoder; + struct input_stream *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)]; +}; + +struct decoder_buffer * +decoder_buffer_new(struct decoder *decoder, struct input_stream *is, + size_t size) +{ + struct decoder_buffer *buffer = + g_malloc(sizeof(*buffer) - sizeof(buffer->data) + size); + + assert(is != NULL); + assert(size > 0); + + buffer->decoder = decoder; + buffer->is = is; + buffer->size = size; + buffer->length = 0; + buffer->consumed = 0; + + return buffer; +} + +void +decoder_buffer_free(struct decoder_buffer *buffer) +{ + assert(buffer != NULL); + + g_free(buffer); +} + +bool +decoder_buffer_is_empty(const struct decoder_buffer *buffer) +{ + return buffer->consumed == buffer->length; +} + +bool +decoder_buffer_is_full(const struct decoder_buffer *buffer) +{ + return buffer->consumed == 0 && buffer->length == buffer->size; +} + +static void +decoder_buffer_shift(struct decoder_buffer *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(struct decoder_buffer *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; +} + +const void * +decoder_buffer_read(const struct decoder_buffer *buffer, size_t *length_r) +{ + if (buffer->consumed >= buffer->length) + /* buffer is empty */ + return NULL; + + *length_r = buffer->length - buffer->consumed; + return buffer->data + buffer->consumed; +} + +void +decoder_buffer_consume(struct decoder_buffer *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); +} diff --git a/src/decoder_buffer.h b/src/decoder_buffer.h new file mode 100644 index 000000000..9d8834ca4 --- /dev/null +++ b/src/decoder_buffer.h @@ -0,0 +1,95 @@ +/* + * Copyright (C) 2003-2009 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#ifndef MPD_DECODER_BUFFER_H +#define MPD_DECODER_BUFFER_H + +#include <stdbool.h> +#include <stddef.h> + +/** + * This objects handles buffered reads in decoder plugins easily. You + * create a buffer object, and use its high-level methods to fill and + * read it. It will automatically handle shifting the buffer. + */ +struct decoder_buffer; + +struct decoder; +struct input_stream; + +/** + * Creates a new buffer. + * + * @param decoder the decoder object, used for decoder_read(), may be NULL + * @param is the input stream object where we should read from + * @param size the maximum size of the buffer + * @return the new decoder_buffer object + */ +struct decoder_buffer * +decoder_buffer_new(struct decoder *decoder, struct input_stream *is, + size_t size); + +/** + * Frees resources used by the decoder_buffer object. + */ +void +decoder_buffer_free(struct decoder_buffer *buffer); + +bool +decoder_buffer_is_empty(const struct decoder_buffer *buffer); + +bool +decoder_buffer_is_full(const struct decoder_buffer *buffer); + +/** + * Read data from the input_stream and append it to the buffer. + * + * @return true if data was appended; false if there is no data + * available (yet), end of file, I/O error or a decoder command was + * received + */ +bool +decoder_buffer_fill(struct decoder_buffer *buffer); + +/** + * Reads data from the buffer. This data is not yet consumed, you + * have to call decoder_buffer_consume() to do that. The returned + * buffer becomes invalid after a decoder_buffer_fill() or a + * decoder_buffer_consume() call. + * + * @param buffer the decoder_buffer object + * @param length_r pointer to a size_t where you will receive the + * number of bytes available + * @return a pointer to the read buffer, or NULL if there is no data + * available + */ +const void * +decoder_buffer_read(const struct decoder_buffer *buffer, size_t *length_r); + +/** + * Consume (delete, invalidate) a part of the buffer. The "nbytes" + * parameter must not be larger than the length returned by + * decoder_buffer_read(). + * + * @param buffer the decoder_buffer object + * @param nbytes the number of bytes to consume + */ +void +decoder_buffer_consume(struct decoder_buffer *buffer, size_t nbytes); + +#endif |