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authorJosh Blum <josh@joshknows.com>2010-01-22 11:56:55 -0800
committerJosh Blum <josh@joshknows.com>2010-01-22 11:56:55 -0800
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tree4a298fb5450f7277b5aaf5210740ae18f818c9aa /usrp2/sdr_lib/cordic.v
parent8f2c33eab9396185df259639082b7d1618585973 (diff)
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Moved usrp2 fpga files into usrp2 subdir.
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+// -*- verilog -*-
+//
+// USRP - Universal Software Radio Peripheral
+//
+// Copyright (C) 2003, 2007 Matt Ettus
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street, Boston, MA 02110-1301 USA
+//
+
+module cordic(clock, reset, enable, xi, yi, zi, xo, yo, zo );
+ parameter bitwidth = 16;
+ parameter zwidth = 16;
+
+ input clock;
+ input reset;
+ input enable;
+ input [bitwidth-1:0] xi, yi;
+ output [bitwidth-1:0] xo, yo;
+ input [zwidth-1:0] zi;
+ output [zwidth-1:0] zo;
+
+ reg [bitwidth+1:0] x0,y0;
+ reg [zwidth-2:0] z0;
+ wire [bitwidth+1:0] x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,x11,x12;
+ wire [bitwidth+1:0] y1,y2,y3,y4,y5,y6,y7,y8,y9,y10,y11,y12;
+ wire [zwidth-2:0] z1,z2,z3,z4,z5,z6,z7,z8,z9,z10,z11,z12;
+
+ wire [bitwidth+1:0] xi_ext = {{2{xi[bitwidth-1]}},xi};
+ wire [bitwidth+1:0] yi_ext = {{2{yi[bitwidth-1]}},yi};
+
+ // Compute consts. Would be easier if vlog had atan...
+ // see gen_cordic_consts.py
+
+ localparam c00 = 15'd8192;
+ localparam c01 = 15'd4836;
+ localparam c02 = 15'd2555;
+ localparam c03 = 15'd1297;
+ localparam c04 = 15'd651;
+ localparam c05 = 15'd326;
+ localparam c06 = 15'd163;
+ localparam c07 = 15'd81;
+ localparam c08 = 15'd41;
+ localparam c09 = 15'd20;
+ localparam c10 = 15'd10;
+ localparam c11 = 15'd5;
+ localparam c12 = 15'd3;
+ localparam c13 = 15'd1;
+ localparam c14 = 15'd1;
+ localparam c15 = 15'd0;
+ localparam c16 = 15'd0;
+
+ always @(posedge clock)
+ if(reset)
+ begin
+ x0 <= 0; y0 <= 0; z0 <= 0;
+ end
+ else// if(enable)
+ begin
+ z0 <= zi[zwidth-2:0];
+ case (zi[zwidth-1:zwidth-2])
+ 2'b00, 2'b11 :
+ begin
+ x0 <= xi_ext;
+ y0 <= yi_ext;
+ end
+ 2'b01, 2'b10 :
+ begin
+ x0 <= -xi_ext;
+ y0 <= -yi_ext;
+ end
+ endcase // case(zi[zwidth-1:zwidth-2])
+ end // else: !if(reset)
+
+ // FIXME need to handle variable number of stages
+ // FIXME should be able to narrow zwidth but quartus makes it bigger...
+ // This would be easier if arrays worked better in vlog...
+ cordic_stage #(bitwidth+2,zwidth-1,0) cordic_stage0 (clock,reset,enable,x0,y0,z0,c00,x1,y1,z1);
+ cordic_stage #(bitwidth+2,zwidth-1,1) cordic_stage1 (clock,reset,enable,x1,y1,z1,c01,x2,y2,z2);
+ cordic_stage #(bitwidth+2,zwidth-1,2) cordic_stage2 (clock,reset,enable,x2,y2,z2,c02,x3,y3,z3);
+ cordic_stage #(bitwidth+2,zwidth-1,3) cordic_stage3 (clock,reset,enable,x3,y3,z3,c03,x4,y4,z4);
+ cordic_stage #(bitwidth+2,zwidth-1,4) cordic_stage4 (clock,reset,enable,x4,y4,z4,c04,x5,y5,z5);
+ cordic_stage #(bitwidth+2,zwidth-1,5) cordic_stage5 (clock,reset,enable,x5,y5,z5,c05,x6,y6,z6);
+ cordic_stage #(bitwidth+2,zwidth-1,6) cordic_stage6 (clock,reset,enable,x6,y6,z6,c06,x7,y7,z7);
+ cordic_stage #(bitwidth+2,zwidth-1,7) cordic_stage7 (clock,reset,enable,x7,y7,z7,c07,x8,y8,z8);
+ cordic_stage #(bitwidth+2,zwidth-1,8) cordic_stage8 (clock,reset,enable,x8,y8,z8,c08,x9,y9,z9);
+ cordic_stage #(bitwidth+2,zwidth-1,9) cordic_stage9 (clock,reset,enable,x9,y9,z9,c09,x10,y10,z10);
+ cordic_stage #(bitwidth+2,zwidth-1,10) cordic_stage10 (clock,reset,enable,x10,y10,z10,c10,x11,y11,z11);
+ cordic_stage #(bitwidth+2,zwidth-1,11) cordic_stage11 (clock,reset,enable,x11,y11,z11,c11,x12,y12,z12);
+
+ assign xo = x12[bitwidth:1];
+ assign yo = y12[bitwidth:1];
+ //assign xo = x12[bitwidth+1:2]; // CORDIC gain is ~1.6, plus gain from rotating vectors
+ //assign yo = y12[bitwidth+1:2];
+ assign zo = z12;
+
+endmodule // cordic
+