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FPGA: Fix overflows in DDC

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Added proper clipping of halfband filter output to handle potential
overflow.

Signed-off-by: michael-west <michael.west@ettus.com>


Original-commit: b2d4eaa8e59110e39ca691187f66a07953bdd0d2
This commit is contained in:
michael-west
2023-01-19 10:05:27 -06:00
committed by Wade Fife
parent b8163da1d1
commit a79dc444a3
1 changed files with 54 additions and 12 deletions
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lib/rfnoc/ddc.v
+54 -12
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@@ -75,8 +75,11 @@ module ddc #(
wire [WIDTH-1:0] i_dds_clip, q_dds_clip;
wire [WIDTH-1:0] i_cic, q_cic;
wire [46:0] i_hb1, q_hb1;
wire [WIDTH-1:0] i_hb1_clip, q_hb1_clip;
wire [46:0] i_hb2, q_hb2;
wire [WIDTH-1:0] i_hb2_clip, q_hb2_clip;
wire [47:0] i_hb3, q_hb3;
wire [WIDTH-1:0] i_hb3_clip, q_hb3_clip;
wire sample_out_stb;
wire strobe_cic, strobe_hb1, strobe_hb2, strobe_hb3;
@@ -471,12 +474,25 @@ module ddc #(
.data_valid(data_valid1), // output data_valid
.dout_1(i_hb1), // output [46 : 0] dout_1
.dout_2(q_hb1)); // output [46 : 0] dout_2
end else begin //if (NUM_HB <= 2)
clip #(.bits_in(47-HB1_SCALE), .bits_out(WIDTH)) clip_hb1_i (
.in(i_hb1[46:HB1_SCALE]),
.out(i_hb1_clip)
);
clip #(.bits_in(47-HB1_SCALE), .bits_out(WIDTH)) clip_hb1_q (
.in(q_hb1[46:HB1_SCALE]),
.out(q_hb1_clip)
);
end else begin //if (NUM_HB == 0)
assign rdy1 = 1'b1;
assign rfd1 = 1'b1;
assign data_valid1 = 1'b1;
assign i_hb1 = 'h0;
assign q_hb1 = 'h0;
assign i_hb1_clip = 'h0;
assign q_hb1_clip = 'h0;
end
if( NUM_HB > 1) begin
hbdec2 hbdec2 (
@@ -488,18 +504,31 @@ module ddc #(
.coef_din(coef_din), // input [17 : 0] coef_din
.rfd(rfd2), // output rfd
.nd(nd2), // input nd
.din_1(i_hb1[23+HB1_SCALE:HB1_SCALE]), // input [23 : 0] din_1
.din_2(q_hb1[23+HB1_SCALE:HB1_SCALE]), // input [23 : 0] din_2
.din_1(i_hb1_clip), // input [23 : 0] din_1
.din_2(q_hb1_clip), // input [23 : 0] din_2
.rdy(rdy2), // output rdy
.data_valid(data_valid2), // output data_valid
.dout_1(i_hb2), // output [46 : 0] dout_1
.dout_2(q_hb2)); // output [46 : 0] dout_2
end else begin //if (NUM_HB <= 2)
clip #(.bits_in(47-HB2_SCALE), .bits_out(WIDTH)) clip_hb2_i (
.in(i_hb2[46:HB2_SCALE]),
.out(i_hb2_clip)
);
clip #(.bits_in(47-HB2_SCALE), .bits_out(WIDTH)) clip_hb2_q (
.in(q_hb2[46:HB2_SCALE]),
.out(q_hb2_clip)
);
end else begin //if (NUM_HB <= 1)
assign rdy2 = 1'b1;
assign rfd2 = 1'b1;
assign data_valid2 = 1'b1;
assign i_hb2 = 'h0;
assign q_hb2 = 'h0;
assign i_hb2_clip = 'h0;
assign q_hb2_clip = 'h0;
end
if( NUM_HB > 2) begin
hbdec3 hbdec3 (
@@ -511,18 +540,31 @@ module ddc #(
.coef_din(coef_din), // input [17 : 0] coef_din
.rfd(rfd3), // output rfd
.nd(nd3), // input nd
.din_1(i_hb2[23+HB2_SCALE:HB2_SCALE]), // input [23 : 0] din_1
.din_2(q_hb2[23+HB2_SCALE:HB2_SCALE]), // input [23 : 0] din_2
.din_1(i_hb2_clip), // input [23 : 0] din_1
.din_2(q_hb2_clip), // input [23 : 0] din_2
.rdy(rdy3), // output rdy
.data_valid(data_valid3), // output data_valid
.dout_1(i_hb3), // output [47 : 0] dout_1
.dout_2(q_hb3)); // output [47 : 0] dout_2
clip #(.bits_in(48-HB3_SCALE), .bits_out(WIDTH)) clip_hb3_i (
.in(i_hb3[47:HB3_SCALE]),
.out(i_hb3_clip)
);
clip #(.bits_in(48-HB3_SCALE), .bits_out(WIDTH)) clip_hb3_q (
.in(q_hb3[47:HB3_SCALE]),
.out(q_hb3_clip)
);
end else begin //if (NUM_HB <= 2)
assign rdy3 = 1'b1;
assign rfd3 = 1'b1;
assign data_valid3 = 1'b1;
assign i_hb3 = 'h0;
assign q_hb3 = 'h0;
assign i_hb3_clip = 'h0;
assign q_hb3_clip = 'h0;
end
endgenerate
reg [23:0] i_unscaled, q_unscaled;
@@ -546,20 +588,20 @@ module ddc #(
2'd1 : begin
last_unscaled <= last_hb1;
strobe_unscaled <= strobe_hb1;
i_unscaled <= i_hb1[23+HB1_SCALE:HB1_SCALE];
q_unscaled <= q_hb1[23+HB1_SCALE:HB1_SCALE];
i_unscaled <= i_hb1_clip;
q_unscaled <= q_hb1_clip;
end
2'd2 : begin
last_unscaled <= last_hb2;
strobe_unscaled <= strobe_hb2;
i_unscaled <= i_hb2[23+HB2_SCALE:HB2_SCALE];
q_unscaled <= q_hb2[23+HB2_SCALE:HB2_SCALE];
i_unscaled <= i_hb2_clip;
q_unscaled <= q_hb2_clip;
end
2'd3 : begin
last_unscaled <= last_hb3;
strobe_unscaled <= strobe_hb3;
i_unscaled <= i_hb3[23+HB3_SCALE:HB3_SCALE];
q_unscaled <= q_hb3[23+HB3_SCALE:HB3_SCALE];
i_unscaled <= i_hb3_clip;
q_unscaled <= q_hb3_clip;
end
endcase // case (hb_rate)
end