Data processing systems

A stream of data is output by a producer 1 and stored in a memory buffer 2 in a shared system memory 3. The producer maintains a producer pointer, which indicate the last address, to which data was written. A consumer 5 reads data from the buffer. It uses the producer pointer to determine which locations in the buffer are available to read. The consumer maintains a consumer pointer, which indicates the last address, from which data was read. The producer uses the consumer pointer to determine which locations in the buffer are available to write. The pointers may be relative to the start of the buffer and may be stored in a shared pointer object 7 in the system memory. The producer and consumer may keep local copies of the pointers. The consumer may read the shared copy of the producer pointer if the difference between its local copy and the last location read falls below a threshold.