Data Delays, Latencies And Throughput - Analog Devices ADSP-BF506F Hardware Reference Manual

Data Delays, Latencies and Throughput

Listing 25-1. Query Semaphore
/* Query semaphore. Denotes "Busy" if its value is nonzero. Wait
until free (or reschedule thread-- see note below). P0 holds
address of semaphore. */
QUERY:
TESTSET ( P0 ) ;
IF !CC JUMP QUERY ;
/* At this point, semaphore has been granted to current thread,
and all other contending threads are postponed because semaphore
value at [P0] is nonzero. Current thread could write thread_id to
semaphore location to indicate current owner of resource. */
R0.L = THREAD_ID ;
B[P0] = R0 ;
/* When done using shared resource, write a zero byte to [P0] */
R0 = 0 ;
B[P0] = R0 ;
SSYNC ;
/* NOTE: Instead of busy idling in the QUERY loop, one can use an
operating system call to reschedule the current thread. */
Data Delays, Latencies and Throughput
For detailed information on latencies and performance estimates on the
DMA and external memory buses, refer to the Chip Bus Hierarchy chapter.
Bus Priorities
For an explanation of prioritization between the various internal buses,
refer to the Chip Bus Hierarchy chapter.
25-4 ADSP-BF50x Blackfin Processor Hardware Reference