Execute.v

   1 module Execute(
   2         input clk,
   3         input Nrst,     /* XXX not used yet */
   4
   5         input stall,
   6         input flush,
   7
   8         input inbubble,
   9         input [31:0] pc,
  10         input [31:0] insn,
  11         input [31:0] cpsr,
  12         input [31:0] op0,
  13         input [31:0] op1,
  14         input [31:0] op2,
  15         input carry,
  16
  17         output reg outstall = 0,
  18         output reg outbubble = 1
  19         );
  20
  21 endmodule
  22
  23 module Multiplier(
  24         input clk,
  25         input Nrst,     /* XXX not used yet */
  26
  27         input start,
  28         input [31:0] acc0,
  29         input [31:0] in0,
  30         input [31:0] in1,
  31
  32         output reg done = 0,
  33         output reg [31:0] result);
  34
  35         reg [31:0] bitfield;
  36         reg [31:0] multiplicand;
  37         reg [31:0] acc;
  38
  39         always @(posedge clk)
  40         begin
  41                 if (start) begin
  42                         bitfield <= in0;
  43                         multiplicand <= in1;
  44                         acc <= acc0;
  45                         done <= 0;
  46                 end else begin
  47                         bitfield <= {2'b00, bitfield[31:2]};
  48                         multiplicand <= {multiplicand[29:0], 2'b00};
  49                         acc <= acc +
  50                                 (bitfield[0] ? multiplicand : 0) +
  51                                 (bitfield[1] ? {multiplicand[30:0], 1'b0} : 0);
  52                         if (bitfield == 0) begin
  53                                 result <= acc;
  54                                 done <= 1;
  55                         end
  56                 end
  57         end
  58 endmodule