#ifndef min
#define min(a,b) (((a) < (b)) ? (a) : (b))
#endif
#ifndef max
#define max(a,b) (((a) > (b)) ? (a) : (b))
#endif
// 无锁缓冲队列.
class circular_buffer
{
public:
circular_buffer ( int buf_size )
: m_buffer_size ( buf_size )
, m_circle_buffer ( NULL )
, m_write_p ( 0 )
, m_read_p ( 0 )
{
m_circle_buffer = new char[m_buffer_size];
}
~circular_buffer()
{
if ( m_circle_buffer )
delete[] m_circle_buffer;
m_circle_buffer = NULL;
}
void clear()
{
m_write_p = 0;
m_read_p = 0;
}
unsigned int size()
{
return m_buffer_size - ( m_write_p - m_read_p );
}
unsigned int used()
{
return m_write_p - m_read_p;
}
unsigned int put_data ( char* buffer, unsigned int len )
{
unsigned int l;
len = _min ( len, m_buffer_size - m_write_p + m_read_p );
/* first put the data starting from fifo->in to buffer end */
l = _min ( len, m_buffer_size - ( m_write_p & ( m_buffer_size - 1 ) ) );
memcpy ( m_circle_buffer + ( m_write_p & ( m_buffer_size - 1 ) ), buffer, l );
/* then put the rest (if any) at the beginning of the buffer */
memcpy ( m_circle_buffer, buffer + l, len - l );
m_write_p += len;
return len;
}
unsigned int get_data ( char* buffer, unsigned int len )
{
unsigned int l;
len = _min ( len, m_write_p - m_read_p );
/* first get the data from fifo->out until the end of the buffer */
l = _min ( len, m_buffer_size - ( m_read_p & ( m_buffer_size - 1 ) ) );
memcpy ( buffer, m_circle_buffer + ( m_read_p & ( m_buffer_size - 1 ) ), l );
/* then get the rest (if any) from the beginning of the buffer */
memcpy ( buffer + l, m_circle_buffer, len - l );
m_read_p += len;
return len;
}
protected:
inline unsigned int _max ( unsigned int a, unsigned int b )
{
return max ( a, b );
}
inline unsigned int _min ( unsigned int a, unsigned int b )
{
return min ( a, b );
}
private:
int m_buffer_size;
char* m_circle_buffer;
unsigned int m_write_p;
unsigned int m_read_p;
};