From 9c29969bbc1b19f251011feaa791d242ac8e5e81 Mon Sep 17 00:00:00 2001
From: Clifford Wolf <clifford@clifford.at>
Date: Sun, 16 Feb 2014 13:45:47 +0100
Subject: Progress in presentation

---
 manual/PRESENTATION_ExAdv/red_or3x1_map.v | 48 +++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 manual/PRESENTATION_ExAdv/red_or3x1_map.v

(limited to 'manual/PRESENTATION_ExAdv/red_or3x1_map.v')

diff --git a/manual/PRESENTATION_ExAdv/red_or3x1_map.v b/manual/PRESENTATION_ExAdv/red_or3x1_map.v
new file mode 100644
index 00000000..24ca9dab
--- /dev/null
+++ b/manual/PRESENTATION_ExAdv/red_or3x1_map.v
@@ -0,0 +1,48 @@
+module \$reduce_or (A, Y);
+
+    parameter A_SIGNED = 0;
+    parameter A_WIDTH = 0;
+    parameter Y_WIDTH = 0;
+    
+    input [A_WIDTH-1:0] A;
+    output [Y_WIDTH-1:0] Y;
+    
+    function integer min;
+        input integer a, b;
+        begin
+            if (a < b)
+                min = a;
+            else
+                min = b;
+        end
+    endfunction
+    
+    genvar i;
+    generate begin
+        if (A_WIDTH == 0) begin
+            assign Y = 0;
+        end
+        if (A_WIDTH == 1) begin
+            assign Y = A;
+        end
+        if (A_WIDTH == 2) begin
+            wire ybuf;
+            OR3X1 g (.A(A[0]), .B(A[1]), .C(1'b0), .Y(ybuf));
+            assign Y = ybuf;
+        end
+        if (A_WIDTH == 3) begin
+            wire ybuf;
+            OR3X1 g (.A(A[0]), .B(A[1]), .C(A[2]), .Y(ybuf));
+            assign Y = ybuf;
+        end
+        if (A_WIDTH > 3) begin
+            localparam next_stage_sz = (A_WIDTH+2) / 3;
+            wire [next_stage_sz-1:0] next_stage;
+            for (i = 0; i < next_stage_sz; i = i+1) begin
+                localparam bits = min(A_WIDTH - 3*i, 3);
+                assign next_stage[i] = |A[3*i +: bits];
+            end
+            assign Y = |next_stage;
+        end
+    end endgenerate
+endmodule
-- 
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