diff options
Diffstat (limited to 'usrp2/fpga/sdr_lib/cordic.v')
| -rwxr-xr-x | usrp2/fpga/sdr_lib/cordic.v | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/usrp2/fpga/sdr_lib/cordic.v b/usrp2/fpga/sdr_lib/cordic.v new file mode 100755 index 000000000..b73e7acf1 --- /dev/null +++ b/usrp2/fpga/sdr_lib/cordic.v @@ -0,0 +1,109 @@ +// -*- 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 + |