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#ifndef min
#define min(a,b) (((a) < (b)) ? (a) : (b))
#endif
#ifndef max
#define max(a,b) (((a) > (b)) ? (a) : (b))
#endif
// 無鎖緩沖隊(duì)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 available()
{
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;
};
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