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: ERROR: [HLS 207-5512] The 'style' option of the 'HLS pipeline' directive or pragma has conflict with 'rewind' option. (dct.cpp:127:43)

Explanation

The FRP style option cannot be used with the rewind option on a pipelined loop.

Example

void buff2stream(unsigned int nblocks, hls::stream_of_blocks<block8x8> &i_buff, hls::stream<float> &stream)
{
  hls::read_buf<block8x8> buff(i_buff);

  buff2stream_l_flat: stream2buff_l_flat: for(int k=0; k<nblocks*64; k++) {
#pragma HLS loop_tripcount min=512*64 max=32400*64
#pragma HLS PIPELINE II=4 rewind
#pragma HLS unroll factor=4
    int n=k/64;
    int i=k%64;
    if (i == 0) {
      buff.acquire();
    }
    stream.write(buff[i]);
    if (i == 64-1) {
      buff.release();
    }
  }
}