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/*
Copyright (C) 2005-2009 Michel de Boer <michel@twinklephone.com>
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 "media_buffer.h"
#include <cstring>
#include "audits/memman.h"
////////////
// PUBLIC
////////////
t_media_buffer::t_media_buffer(int size) {
buf_size = size;
empty = true;
buffer = new unsigned char[size];
MEMMAN_NEW_ARRAY(buffer);
pos_start = 0;
pos_end = 0;
}
t_media_buffer::~t_media_buffer() {
MEMMAN_DELETE_ARRAY(buffer);
delete [] buffer;
}
void t_media_buffer::add(unsigned char *data, int len) {
int data_start, data_end;
mtx.lock();
// The amount of data should fit in the buffer.
if (len > buf_size) {
mtx.unlock();
return;
}
int current_size_content = size_content();
if (empty) {
data_start = 0;
data_end = len - 1;
pos_start = 0;
empty = false;
} else {
data_start = (pos_end + 1) % buf_size;
data_end = (data_start + len - 1) % buf_size;
}
// Copy the data into the buffer
if (data_end >= data_start) {
memcpy(buffer + data_start, data, len);
} else {
// The data wraps around the end of the buffer
memcpy(buffer + data_start, data, buf_size - data_start);
memcpy(buffer, data + buf_size - data_start, data_end + 1);
}
// Check if the new data wrapped over the start of the old data.
// If so, then advance the start of the old data behind the end of the new
// data as new data has erased the oldest data.
if (buf_size - current_size_content < len) {
pos_start = (data_end + 1) % buf_size;
}
pos_end = data_end;
mtx.unlock();
}
bool t_media_buffer::get(unsigned char *data, int len) {
mtx.lock();
if (len > size_content()) {
mtx.unlock();
return false;
}
// Retrieve the data from the buffer
if (pos_start + len <= buf_size) {
memcpy(data, buffer + pos_start, len);
} else {
// The data to be retrieved wraps around the end of
// the buffer.
memcpy(data, buffer + pos_start, buf_size - pos_start);
memcpy(data + buf_size - pos_start, buffer, len - buf_size + pos_start);
}
pos_start = (pos_start + len) % buf_size;
// Check if buffer is empty
if (pos_start == (pos_end + 1) % buf_size) {
empty = true;
}
mtx.unlock();
return true;
}
int t_media_buffer::size_content(void) {
int len;
mtx.lock();
if (empty) {
len = 0;
} else if (pos_end >= pos_start) {
len = pos_end - pos_start + 1;
} else {
len = pos_end + buf_size - pos_start + 1;
}
mtx.unlock();
return len;
}
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