Merge branch 'master' of nyus.joshuawise.com:/git/firearm
[firearm.git] / 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
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