VHDL: Resolved BFM control/command channel.

gistfile1.vhdl

ype bfm_uctrl_vector_t is
  array (integer range <>) of bfm_uctrl_t;

function resolve_bfm_ctrl (
  s : bfm_uctrl_vector_t ) return bfm_uctrl_t;

subtype bfm_ctrl_t is
  resolve_bfm_ctrl bfm_uctrl_t;

procedure do_req (
  signal   ctrl : inout bfm_ctrl_t;
  constant req  : in    bfm_req_t;
  variable cmd  : inout bfm_ctrl_t );

function resolve_bfm_ctrl (
  s : bfm_uctrl_vector_t) return bfm_uctrl_t is

  variable result      : bfm_uctrl_t;
  variable req_drivers : natural;
  variable ack_drivers : natural;
begin
  for i in s'range loop
    assert s(i).req = none or not s(i).ack
      report "resolve_bfm_ctrl: Are you a client or a server?"
      severity failure;
     
    if s(i).req /= none then
      req_drivers := req_drivers + 1;
      result := s(i);
    elsif s(i).ack then
      ack_drivers := ack_drivers + 1;
      if req_drivers = 0 then
        result := s(i);
      end if;
    end if;
  end loop;

  assert ack_drivers <= 1
    report "resolve_bfm_ctrl: More than one acknowledge active."
    severity failure;

  if req_drivers > 1 then
    report "resolve_bfm_ctrl: More than one request active."
      severity failure;
    result.req := none;
  end if;

  result.ack := ack_drivers = 1;

  return result;
end function;

procedure do_req (
  signal   ctrl : inout bfm_ctrl_t;
  constant req  : in    bfm_req_t;
  variable cmd  : inout bfm_ctrl_t ) is
begin
  cmd.req := req;
  cmd.ack := false;

  ctrl <= cmd;
  wait until ctrl.ack;

  ctrl.req <= none;
  wait for 0 ns;

  cmd := ctrl;
end procedure;