Write data into the ringbuffer.
@param rb a pointer to the ringbuffer structure. @param src a pointer to the data to be written to the ringbuffer. @param cnt the number of bytes to write.
@return the number of bytes write, which may range from 0 to cnt
See Implementation
Write data into the ringbuffer.
@param rb a pointer to the ringbuffer structure. @param src a pointer to the data to be written to the ringbuffer. @param cnt the number of bytes to write.
@return the number of bytes write, which may range from 0 to cnt