Self-adjusting elasticity data buffer with preload value

Abstract

The drift between a write pointer and a read pointer processing packets of data through a FIFO buffer is compensated for by adjusting the start of the read pointer relative to the write pointer. The FIFO buffer is sized to include a number of storage cells equal to the product of the maximum frequency offset between the write clock and read clock and the maximum number of data units in a packet. Initially the start of the read pointer is delayed, relative to the write pointer, by a portion of the number of storage cells in the FIFO. During the processing of a data packet it is determined whether the read pointer is drifting toward or away from the write pointer. If the read pointer is drifting away from the write pointer, for subsequent data packets, the read pointer is started almost immediately after the write pointer writes to the first storage cell in the FIFO. If the read pointer is drifting toward the write pointer, for subsequent data packets, the read pointer is started almost immediately prior to the time at which the write pointer writes to the last storage cell in the FIFO.