diff options
Diffstat (limited to 'fpga/usrp3/lib/dsp/small_hb_dec.v')
-rw-r--r-- | fpga/usrp3/lib/dsp/small_hb_dec.v | 124 |
1 files changed, 0 insertions, 124 deletions
diff --git a/fpga/usrp3/lib/dsp/small_hb_dec.v b/fpga/usrp3/lib/dsp/small_hb_dec.v deleted file mode 100644 index fc776c2d7..000000000 --- a/fpga/usrp3/lib/dsp/small_hb_dec.v +++ /dev/null @@ -1,124 +0,0 @@ -// -// Copyright 2011 Ettus Research LLC -// - - -// Short halfband decimator (intended to be followed by another stage) -// Implements impulse responses of the form [A 0 B 0.5 B 0 A] -// -// These taps designed by halfgen4 from ldoolittle: -// 2 * 131072 * halfgen4(.75/8,2) -module small_hb_dec - #(parameter WIDTH=18) - (input clk, - input rst, - input bypass, - input run, - input stb_in, - input [WIDTH-1:0] data_in, - output reg stb_out, - output reg [WIDTH-1:0] data_out); - - // Round off inputs to 17 bits because of 18 bit multipliers - localparam INTWIDTH = 17; - wire [INTWIDTH-1:0] data_rnd; - wire stb_rnd; - - round_sd #(.WIDTH_IN(WIDTH),.WIDTH_OUT(INTWIDTH)) round_in - (.clk(clk),.reset(rst),.in(data_in),.strobe_in(stb_in),.out(data_rnd),.strobe_out(stb_rnd)); - - - reg stb_rnd_d1; - reg [INTWIDTH-1:0] data_rnd_d1; - always @(posedge clk) stb_rnd_d1 <= stb_rnd; - always @(posedge clk) data_rnd_d1 <= data_rnd; - - wire go; - reg phase, go_d1, go_d2, go_d3, go_d4; - always @(posedge clk) - if(rst | ~run) - phase <= 0; - else if(stb_rnd_d1) - phase <= ~phase; - assign go = stb_rnd_d1 & phase; - always @(posedge clk) - if(rst | ~run) - begin - go_d1 <= 0; - go_d2 <= 0; - go_d3 <= 0; - go_d4 <= 0; - end - else - begin - go_d1 <= go; - go_d2 <= go_d1; - go_d3 <= go_d2; - go_d4 <= go_d3; - end - - wire [17:0] coeff_a = -10690; - wire [17:0] coeff_b = 75809; - - reg [INTWIDTH-1:0] d1, d2, d3, d4 , d5, d6; - always @(posedge clk) - if(stb_rnd_d1 | rst) - begin - d1 <= data_rnd_d1; - d2 <= d1; - d3 <= d2; - d4 <= d3; - d5 <= d4; - d6 <= d5; - end - - reg [17:0] sum_a, sum_b, middle, middle_d1; - - always @(posedge clk) - if(go) - begin - sum_a <= {data_rnd_d1[INTWIDTH-1],data_rnd_d1} + {d6[INTWIDTH-1],d6}; - sum_b <= {d2[INTWIDTH-1],d2} + {d4[INTWIDTH-1],d4}; - //middle <= {d3[INTWIDTH-1],d3}; - middle <= {d3,1'b0}; - end - - always @(posedge clk) - if(go_d1) - middle_d1 <= middle; - - wire [17:0] sum = go_d1 ? sum_b : sum_a; - wire [17:0] coeff = go_d1 ? coeff_b : coeff_a; - wire [35:0] prod; - MULT18X18S mult(.C(clk), .CE(go_d1 | go_d2), .R(rst), .P(prod), .A(coeff), .B(sum) ); - - localparam ACCWIDTH = 30; - reg [ACCWIDTH-1:0] accum; - - always @(posedge clk) - if(rst) - accum <= 0; - else if(go_d2) - accum <= {middle_d1[17],middle_d1[17],middle_d1,{(16+ACCWIDTH-36){1'b0}}} + {prod[35:36-ACCWIDTH]}; - else if(go_d3) - accum <= accum + {prod[35:36-ACCWIDTH]}; - - wire [WIDTH:0] accum_rnd; - wire [WIDTH-1:0] accum_rnd_clip; - - wire stb_round; - - round_sd #(.WIDTH_IN(ACCWIDTH),.WIDTH_OUT(WIDTH+1)) round_acc - (.clk(clk), .reset(rst), .in(accum), .strobe_in(go_d4), .out(accum_rnd), .strobe_out(stb_round)); - - clip #(.bits_in(WIDTH+1),.bits_out(WIDTH)) clip (.in(accum_rnd), .out(accum_rnd_clip)); - - // Output - always @(posedge clk) - begin - stb_out <= bypass ? stb_in : stb_round; - data_out <= bypass ? data_in : accum_rnd_clip; - end - - -endmodule // small_hb_dec |