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Diffstat (limited to 'usrp1/sdr_lib/cordic.v')
| -rwxr-xr-x | usrp1/sdr_lib/cordic.v | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/usrp1/sdr_lib/cordic.v b/usrp1/sdr_lib/cordic.v new file mode 100755 index 000000000..ea4119426 --- /dev/null +++ b/usrp1/sdr_lib/cordic.v @@ -0,0 +1,109 @@ +// -*- verilog -*- +// +// USRP - Universal Software Radio Peripheral +// +// Copyright (C) 2003 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 + +`define c00 16'd8192 +`define c01 16'd4836 +`define c02 16'd2555 +`define c03 16'd1297 +`define c04 16'd651 +`define c05 16'd326 +`define c06 16'd163 +`define c07 16'd81 +`define c08 16'd41 +`define c09 16'd20 +`define c10 16'd10 +`define c11 16'd5 +`define c12 16'd3 +`define c13 16'd1 +`define c14 16'd1 +`define c15 16'd0 +`define c16 16'd0 + + always @(posedge clock) + if(reset) + begin + x0 <= #1 0; y0 <= #1 0; z0 <= #1 0; + end + else if(enable) + begin + z0 <= #1 zi[zwidth-2:0]; + case (zi[zwidth-1:zwidth-2]) + 2'b00, 2'b11 : + begin + x0 <= #1 xi_ext; + y0 <= #1 yi_ext; + end + 2'b01, 2'b10 : + begin + x0 <= #1 -xi_ext; + y0 <= #1 -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 + |