/* * 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 "config.h" #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); } bool decoder_buffer_skip(struct decoder_buffer *buffer, size_t nbytes) { size_t length; const void *data; bool success; /* this could probably be optimized by seeking */ while (true) { data = decoder_buffer_read(buffer, &length); if (data != NULL) { if (length > nbytes) length = nbytes; decoder_buffer_consume(buffer, length); nbytes -= length; if (nbytes == 0) return true; } success = decoder_buffer_fill(buffer); if (!success) return false; } }