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

[firearm.git] / Execute.v

diff --git a/Execute.v b/Execute.v
index 5ba0a9a96aea7101a701cc0496893581f9c8e4a1..e00e93d240e13ea87256b601768673fb2bf8117c 100644 (file)
--- a/Execute.v
+++ b/Execute.v
@@ -19,3 +19,40 @@ module Execute(
        );
        
 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