2. Catapult - Interfaces!

Simple example to get familiar with Catapult HLS flow

Catapult IO components

This part is a mess for me at the beginning actually at the moment also, but I will try to make more experiment. I do not really know why they have to make it so compilcated. As mentioned in the userguide, they provides 20 types of IOs (10 for Input and 10 for Output)

Input	Output
ccs_in	ccs_out
ccs_in_rdy	ccs_out_prereg
ccs_in_rdy_coupled	ccs_out_prereg_vld
ccs_in_vld	ccs_out_rdy
ccs_in_wait	ccs_out_vld
ccs_in_pipe	ccs_out_wait
ccs_in_buf_wait	ccs_out_pipe
ccs_ctrl_in_buf_wait	ccs_out_buf_wait
ccs_in_wait_coupled	ccs_out_skidbuf_wait
ccs_in_wait_szchan	ccs_stallbuf

Based on userguide, it describes:

Having VALID or READY signal or not.
- _rdy ready signal is available
- vld valid signal is available
- wait pipe both ready and valid is available
Data registerd in IO component or not
Handshaking signals registered in the IO component or not
Process registerd in the main process ot not

What are IO component and main process?

Cai User guide nhi shit

Wait Controller

Mỗi IO component có đuôi _wait handshake khi compile ra RTL sẽ sinh ra một khối Wait Controller. Tương ứng với IO components ta sẽ có 2 loại Wait Controller: Input và Output

Trong RTL, netlist, các khối Wait Controller sẽ được mô tả với đuôi *:rsci và staller

Input wait controller

Output wait controller

AXI4 Stream interface

In order for Catapult recognizes _TLAST and _TUSER correctly, it is required to declare Stream_t in the following order:

struct Stream_t {
  uint128 TDATA;
  bool    TUSER;
  bool    TLAST;
};

_TLAST must be in the last.

Catapult does not support byte positioning, thereforem it requires

_TSTRB, _TKEEP of input are all 1s, if not it will assert WARNING when running RTL simulation.