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/*
* 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;
}
}
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