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/*
* UltraStar Deluxe - Karaoke Game
*
* UltraStar Deluxe is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* 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; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*/
#include "ringbuffer.hpp"
#include <stdlib.h>
#include <string.h>
namespace usdx
{
RingBuffer::RingBuffer(int size):
buffer_count(0),
buffer_size(size),
write_pos(0),
read_pos(0)
{
ring_buffer = (char*)malloc(size);
if (ring_buffer == NULL)
throw "No memory";
}
RingBuffer::~RingBuffer()
{
free(ring_buffer);
}
int RingBuffer::read(char *buffer, int count)
{
// check if there is something to do
if (count <= 0)
return count;
// check if the buffer is NULL
if (buffer == NULL)
return -1;
// adjust output count
if (count > buffer_count)
{
//DebugWriteln('Read too much: ' + inttostr(count) +',count:'+ inttostr(BufferCount) + '/size:' + inttostr(BufferSize));
count = buffer_count;
}
// copy data to output buffer
// first step: copy from the area between the read-position and the end of the buffer
int part_count = (count < buffer_size - read_pos) ? count : (buffer_size - read_pos);
memcpy(buffer, ring_buffer + read_pos, part_count);
// second step: if we need more data, copy from the beginning of the buffer
if (part_count < count)
memcpy(buffer + part_count, ring_buffer, count - part_count);
// mark the copied part of the buffer as free
buffer_count = buffer_count - count;
read_pos = (read_pos + count) % buffer_size;
return count;
}
int RingBuffer::write(char *buffer, int count)
{
// check for a reasonable request
if (count <= 0)
return count;
// check if the buffer is NULL
if (buffer == NULL)
return -1;
// skip input data if the input buffer is bigger than the ring-buffer
if (count > buffer_size)
{
//DebugWriteln('Write skip data:' + inttostr(count) +',count:'+ inttostr(BufferCount) + '/size:' + inttostr(BufferSize));
buffer += count - buffer_size;
count = buffer_size;
}
// first step: copy to the area between the write-position and the end of the buffer
int part_count = (count < buffer_size - write_pos) ? count : (buffer_size - write_pos);
memcpy(ring_buffer + write_pos, buffer, part_count);
// second step: copy data to front of buffer
if (part_count < count)
memcpy(ring_buffer, buffer + part_count, count - part_count);
// update info
buffer_count = (buffer_count + count < buffer_size) ? (buffer_count + count) : buffer_size;
write_pos = (write_pos + count) % buffer_size;
// if the buffer is full, we have to reposition the read-position
if (buffer_count == buffer_size)
read_pos = write_pos;
return count;
}
int RingBuffer::get_available()
{
return buffer_count;
}
int RingBuffer::get_size()
{
return buffer_size;
}
void RingBuffer::flush()
{
read_pos = 0;
write_pos = 0;
buffer_count = 0;
}
};
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