except-new.pdl

exn-pipe cpu(pc :uint<16>)[imem :uint<8>[16]<a,a>, acc :uint<4>[0]<c,s>] :uint<4> {
    start(imem);
    uint<8> insn <- imem[pc];
    end(imem);
    ---
    print("PC: %h", pc);
    print("INSN: %h", insn);
    opcode = insn{7:4};
    imm = insn{3:0};
    done = opcode == 0;
    add = opcode == 1;
    sub = opcode == 2;
    ex = !(done || add || sub);
    start(acc);
    acc_val = acc[];
    split
    {
      case: (add)
      {
	acc[] <- acc_val + imm;
      }
      case: (sub)
      {
        acc[] <- acc_val - imm;
      }
      case: (ex)
      {
        except();
      }
    }
    if (done)
    {
      output acc_val;
    } else
    {
      call cpu(pc + 1);
    }
    end(acc);
    ---
commit:
    print("no exn here!");
except:
    print("exception!");
}


circuit {
   ti = memory(uint<8>, 16);
   acc = register(uint<4>, 1);
   c = new cpu[ti, acc];
   call c(u0<16>);
}