1 files changed, 84 insertions, 0 deletions
diff --git a/fpga/usrp2/sdr_lib/halfband_ideal.v b/fpga/usrp2/sdr_lib/halfband_ideal.v
new file mode 100644
index 000000000..484cfff2a
--- /dev/null
+++ b/fpga/usrp2/sdr_lib/halfband_ideal.v
@@ -0,0 +1,84 @@
+module halfband_ideal (
+    input                           clock,
+    input                           reset,
+    input                           enable,
+    input                           strobe_in,
+    input   wire    signed  [17:0]  data_in,
+    output  reg                     strobe_out,
+    output  reg     signed  [17:0]  data_out
+) ;
+
+    parameter                       decim   = 1 ;
+    parameter                       rate    = 2 ;
+
+    reg signed              [40:0]  temp ;
+    reg signed              [17:0]  delay[30:0] ;
+    reg signed              [17:0]  coeffs[30:0] ;
+    reg                     [7:0]   count ;
+    integer                         i ;
+
+    initial begin
+        for( i = 0 ; i < 31 ; i = i + 1 ) begin
+            coeffs[i] = 18'd0 ;
+        end
+        coeffs[0]   = -1390 ;
+        coeffs[2]   = 1604 ;
+        coeffs[4]   = -1896 ;
+        coeffs[6]   = 2317 ;
+        coeffs[8]   = -2979 ;
+        coeffs[10]  = 4172 ;
+        coeffs[12]  = -6953 ;
+        coeffs[14]  = 20860 ;
+        coeffs[15]  = 32768 ;
+        coeffs[16]  = 20860 ;
+        coeffs[18]  = -6953 ;
+        coeffs[20]  = 4172 ;
+        coeffs[22]  = -2979 ;
+        coeffs[24]  = 2317 ;
+        coeffs[26]  = -1896 ;
+        coeffs[28]  = 1604 ;
+        coeffs[30]  = -1390 ;
+    end
+
+    always @(posedge clock) begin
+        if( reset ) begin
+            count <= 0 ;
+            for( i = 0 ; i < 31 ; i = i + 1 ) begin
+                delay[i] <= 18'd0 ;
+            end
+            temp        <= 41'd0 ;
+            data_out    <= 18'd0 ;
+            strobe_out  <= 1'b0 ;
+        end else if( enable ) begin
+
+            if( (decim && (count == rate-1)) || !decim ) 
+                strobe_out <= strobe_in ;
+            else
+                strobe_out <= 1'b0 ;
+            
+
+            if( strobe_in ) begin
+                // Increment decimation count
+                count <= count + 1 ;
+
+                // Shift the input
+                for( i = 30 ; i > 0 ; i = i - 1 ) begin
+                    delay[i] = delay[i-1] ;
+                end
+                delay[0] = data_in ;
+
+                // clear the temp reg
+                temp = 18'd0 ;
+                if( (decim && (count == rate-1)) || !decim ) begin
+                    count <= 0 ;
+                    for( i = 0 ; i < 31 ; i = i + 1 ) begin
+                        // Multiply Accumulate
+                        temp = temp + delay[i]*coeffs[i] ;
+                    end
+                    // Assign data output
+                    data_out <= temp >>> 15 ;
+                end
+            end
+        end
+    end
+endmodule