Merge nyus:/storage/git/firearm
[firearm.git] / Execute.v
index 64999fa..e00e93d 100644 (file)
--- a/Execute.v
+++ b/Execute.v
@@ -9,15 +9,50 @@ module Execute(
        input [31:0] pc,
        input [31:0] insn,
        input [31:0] cpsr,
-       input reg [31:0] op0,
-       input reg [31:0] op1,
-       input reg [31:0] op2,
-       input reg carry,
+       input [31:0] op0,
+       input [31:0] op1,
+       input [31:0] op2,
+       input carry,
        
        output reg outstall = 0,
-       output reg outbubble = 1,
+       output reg outbubble = 1
        );
+       
+endmodule
 
+module Multiplier(
+       input clk,
+       input Nrst,     /* XXX not used yet */
+       
+       input start,
+       input [31:0] acc0,
+       input [31:0] in0,
+       input [31:0] in1,
+       
+       output reg done = 0,
+       output reg [31:0] result);
        
+       reg [31:0] bitfield;
+       reg [31:0] multiplicand;
+       reg [31:0] acc;
        
+       always @(posedge clk)
+       begin
+               if (start) begin
+                       bitfield <= in0;
+                       multiplicand <= in1;
+                       acc <= acc0;
+                       done <= 0;
+               end else begin
+                       bitfield <= {2'b00, bitfield[31:2]};
+                       multiplicand <= {multiplicand[29:0], 2'b00};
+                       acc <= acc +
+                               (bitfield[0] ? multiplicand : 0) +
+                               (bitfield[1] ? {multiplicand[30:0], 1'b0} : 0);
+                       if (bitfield == 0) begin
+                               result <= acc;
+                               done <= 1;
+                       end
+               end
+       end
 endmodule
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