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

MODULE FPDivider(   (*NW 9.9.2016*)
  IN clk, run: BIT; x, y: WORD;
  OUT stall: BIT; z: WORD);

  REG (clk) S: [5] BIT;   (*state*)
    R: [24] BIT;   (*remainder*)
    Q: [26] BIT;   (*quotient*)

  VAR sign: BIT;
    xe, ye: [8] BIT;
    e0, e1: [9] BIT;
    r0,  r1, d: [25] BIT;
    q0: [26] BIT;
    z0, z1: [25] BIT;

BEGIN
  sign := x.31 ^ y.31;   (*xor*)
  xe := x[30:23]; ye := y[30:23];
  e0 := {0'1, xe} - {0'1, ye};
  e1 := e0 + 126 + Q.25;
  stall := run & (S # 26);

  r0 := (S = 0) -> {1'2, x[22:0]} : {R, 0'1};
  r1 := d.24 -> 0 : d;
  d := r0 - {1'2, y[22:0]};
  q0 := (S = 0) -> 0 : Q;

  z0 := Q.25 -> Q[25:1] : Q[24:0];  (* normalize*)
  z1 := z0 + 1;   (*round*)
  z := (xe = 0) -> 0 :
    (ye = 0) -> {sign, 0FFH'8, 0'23} :  (*divide by 0*)
    ~e1.8 -> {sign, e1[7:0], z1[23:1]} :
    ~e1.7 -> {sign, 0FFH'8, z0[23:1]} : 0;   (*overflow*)

  R := r1[23:0];
  Q := {q0[24:0], ~d.24};
  S := run -> S+1 : 0
END FPDivider.