US 7,570,534 B2
Enqueue event first-in, first-out buffer (FIFO)
James Wang, Milpitas, Calif. (US); and Zongjian Chen, Palo Alto, Calif. (US)
Assigned to Apple Inc., Cupertino, Calif. (US)
Filed on Feb. 15, 2007, as Appl. No. 11/675,341.
Prior Publication US 2008/0198671 A1, Aug. 21, 2008
Int. Cl. G11C 7/00 (2006.01); G06F 3/00 (2006.01); G06F 5/00 (2006.01); G06F 13/36 (2006.01)
U.S. Cl. 365—221  [365/189.15; 365/189.16; 365/189.2; 365/189.12; 710/52; 710/310] 19 Claims
OG exemplary drawing
 
1. An apparatus comprising:
a queue configured to store a plurality of data items, wherein each data item has a type which is one of a plurality of types of data items being stored in the queue;
write control logic coupled to the queue and configured to operate in a write clock domain, wherein the write control logic is configured to maintain one or more write pointers for each of the plurality of types, wherein the write pointers identify entries in the queue, and wherein the write control logic is configured to update the write pointer corresponding to an input type for an input data item written to the queue;
a first-in, first-out buffer (FIFO) coupled to the write control logic, wherein the write control logic is configured to enqueue a write event in the FIFO to transport the write event to a read clock domain different from the write clock domain; and
read control logic coupled to the FIFO and configured to operate in the read clock domain, wherein the read control logic is configured to maintain one or more second write pointers for each of the plurality of types, and wherein the read control logic is configured to update the second write pointer corresponding to the input type responsive to receiving the write event from the FIFO.