Function hbm_writer_kernel 

pub fn hbm_writer_kernel(
    clock_reset: ClockReset,
    input: WriterInput,
    q: HbmWriterQ,
) -> (WriterOutput, HbmWriterD)

The writer’s logic.

• Inputs: clock_reset (reset forces every valid low), the signer’s beat, the memory’s readys and B response, and q, the current WriterState.
• Outputs: the AXI4 write request, beat_ready back to the signer, the acknowledged-frame count and the sticky error; plus HbmWriterD, the next state.
• Timing: purely combinational within one cycle; the counters advance at the next clock edge. frames_written and error are the registered values, so they lag the B transfer by one clock.