Free Running Pipeline - Free Running Pipeline - 2026.1 English - UG1448

Vitis HLS Messaging (UG1448)

Document ID
UG1448
Release Date
2026-06-23
Version
2026.1 English

Description

Warning: [HLS 200-1969] Disabling free running pipeline (frp) architecture on pipeline 'VITIS_LOOP_5_1_VITIS_LOOP_11_3' in module 'writer', because it has a write operation on a stream of blocks via port: out_r.

Explanation

A Write operation to a stream of blocks is not supported inside an FRP pipeline.

Example

void writer(hls::stream_of_blocks<ppbuf> &out, int in[M][N]) {
  for(unsigned j = 0; j < M; ++j) {
    int tot = 0;
    for(unsigned k = 0; k < 32; ++k) {
         tot += k;
    }
    hls::write_lock<ppbuf> arr(out);
    for(unsigned i = 0; i < N; ++i) {
#pragma HLS pipeline II=1
        arr[N-1-i] = in[j][i] + tot;
     }
   }
}