Using Streams in Parallel - 2020.2 English

Versal ACAP AI Engine Programming Environment User Guide (UG1076)

Document ID
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2020.2 English

For streaming input and output interfaces, when the performance is limited by the streaming interface, it is possible to use two streaming inputs or two streaming outputs in parallel. To use two parallel streams, it is recommended to use the following pairs of macros, where idx1 and idx2 are the two streams. Add the restrict keyword to the stream ports to optimize them for parallel processing. The macro is operating on 32 bits every cycle, or 128 bits per four cycles.

READINCR(SS_rsrc1, idx1) and READINCR(SS_rsrc2, idx2)
READINCRW(WSS_rsrc1, idx1) and READINCRW(WSS_rsrc2, idx2)
WRITEINCR(MS_rsrc1, idx1, val) and WRITEINCR(MS_rsrc2, idx2, val)
WRITEINCRW(WMS_rsrc1, idx1, val) and WRITEINCRW(WMS_rsrc2, idx2, val)

The following example code shows two parallel input streams using pipelining with an interval of 1.

void simple( input_stream_int32 * restrict data0, input_stream_int32 * restrict data1, 
    output_stream_int32 * restrict out) {
   for(int i=0; i<1024; i++)
     int32_t d = READINCR(SS_rsrc1, data0) ;
     int32_t e = READINCR(SS_rsrc2, data1) ;