Dma Access; Notes On Read Optimization - Analog Devices SHARC ADSP-214 Series Hardware Reference Manual

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DMA Access

shows an example of external port DMA using read

optimization.

Listing 3-3. EPDMA With Read Optimization

ustat1=dm(SDCTL);

bit set ustat1 SDROPT|SDMODIFY2;

dm(SDCTL)=ustat1;

dm(DMAC1)=r0;

dm(DMAC1)=r0;

The core and the DMA engine take advantage of the major improvements

during reads using read optimization. However, in situations where both

the core and DMA need to read from different internal memory banks

with different modifiers at the same time, programs need to choose

whether or not to use optimization. Note that from a throughput prospec-

tive, external port arbitration also is a factor. A good rule is that the

requester with the higher priority should have the same modifier as

. In other words, if DMA has a higher priority over the core, then the

DMA modifier should match the

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dm(IIEP1)=r0;

dm(IMEP1)=r0;

dm(ICEP1)=r0;

dm(EMEP1)=r0;

dm(EIEP1)=r0;

External Port

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