Project-Oberon-BlackBox/BlackBox/Po/Files/FPMultiplier.Lola.txt

MODULE FPMultiplier(
  IN clk, run: BIT; x, y: WORD;
  OUT stall: BIT; z: WORD);

  REG (clk) S: [5] BIT;   (*state*)
    B2, A2: [24] BIT;

  VAR sign: BIT;
    xe, ye: [8] BIT;
    e0, e1: [9] BIT;
    B0: [25] BIT;
    B00, B01, B1, A1, A0, z0: [24] BIT;

BEGIN sign := x.31 ^ y.31;   (*xor*)
  xe := x[30:23]; ye := y[30:23]; e0 := {0'1, xe} + {0'1, ye};
  B00 := (S = 0) -> 0 : B2;
  B01 := A0.0 -> {1'1, y[22:0]} : 0;
  B0 := {0'1, B00} + {0'1, B01};
  B1 := B0[24:1];
  A0 := (S = 0) -> {1'1, x[22:0]} : A2;
  A1 := {B0.0, A0[23:1]};

  e1 := e0 - 127 + B1.23;
  z0 := B1.23 -> B1 : {B1[22:0], A1.23};
  z := (xe = 0) | (ye = 0) -> 0 :
    ~e1.8 -> {sign, e1[7:0], z0[22:0]} :
    ~e1.7 -> {sign, 0FFH'8, z0[22:0]} : 0;  (*overflow*)
  stall := run & (S # 23);

  B2 := B1; A2 := A1;
  S := run -> S+1 : 0;
END FPMultiplier.