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`timescale 1ns / 1ps
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`timescale 1ns / 1ps
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//////////////////////////////////////////////////////////////////////////////////
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//////////////////////////////////////////////////////////////////////////////////
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// Company:
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// Engineer: Yann Vernier
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// Engineer: Yann Vernier
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//
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//
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// Create Date: 21:37:32 02/19/2011
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// Create Date: 21:37:32 02/19/2011
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// Design Name:
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// Design Name:
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// Module Name: vector2scanline
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// Module Name: vector2scanline
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// Tool versions:
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// Tool versions:
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// Description: Converts vector data (exposed points) into raster video
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// Description: Converts vector data (exposed points) into raster video
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//
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//
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// Dependencies:
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// Dependencies:
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//
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//
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// Revision: $Id$
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// $Log$
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// Additional Comments:
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//
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//////////////////////////////////////////////////////////////////////////////////
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//////////////////////////////////////////////////////////////////////////////////
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module vector2scanline(
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module vector2scanline(
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input clk, // clock
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clk_i, // clock
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input strobe, // new exposed pixel trigger
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strobe_i, // new exposed pixel trigger
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input [9:0] x, // column of exposed pixel
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x_i, // column of exposed pixel
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input [9:0] y, // row of exposed pixel
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y_i, // row of exposed pixel
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// Video output interface
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// Video output interface
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input [9:0] xout, // current pixel column
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xout_i, // current pixel column
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input [9:0] yout, // current pixel row
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yout_i, // current pixel row
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input newline, // line buffer swap signal
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newline_i, // line buffer swap signal
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input newframe, // new frame signal
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newframe_i, // new frame signal
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output [7:0] pixel // output pixel intensity
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pixel_o // output pixel intensity
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);
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/*AUTOARG*/);
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// TODO: figure out how to apply parameters to the port sizes above
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parameter X_WIDTH = 10; // bit width of column coordinate
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parameter X_WIDTH = 10; // bit width of column coordinate
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parameter Y_WIDTH = 10; // bit width of row coordinate
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parameter Y_WIDTH = 10; // bit width of row coordinate
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parameter HIST_WIDTH = 10; // log2 of maximum lit pixels (exposure buffer)
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parameter HIST_WIDTH = 10; // log2 of maximum lit pixels (exposure buffer)
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parameter AGE_WIDTH = 8; // width of exposure age counter
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parameter AGE_WIDTH = 8; // width of exposure age counter
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input clk_i;
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input strobe_i;
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input [X_WIDTH-1:0] x_i;
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input [Y_WIDTH-1:0] y_i;
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input [X_WIDTH-1:0] xout_i;
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input [Y_WIDTH-1:0] yout_i;
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input newline_i, newframe_i;
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output [AGE_WIDTH-1:0] pixel_o;
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// positions and age of lit pixels
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// positions and age of lit pixels
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reg [X_WIDTH+Y_WIDTH+AGE_WIDTH-1:0] exposures [(2**HIST_WIDTH)-1:0];
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reg [X_WIDTH+Y_WIDTH+AGE_WIDTH-1:0] exposures [(2**HIST_WIDTH)-1:0];
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// output register of exposed pixels buffer
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// output register of exposed pixels buffer
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reg [X_WIDTH+Y_WIDTH+AGE_WIDTH-1:0] expr;
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reg [X_WIDTH+Y_WIDTH+AGE_WIDTH-1:0] expr;
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// data for next pixel to store in exposure buffer
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// data for next pixel to store in exposure buffer
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wire [X_WIDTH-1:0] expx;
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wire [X_WIDTH-1:0] expx;
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wire [Y_WIDTH-1:0] expy;
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wire [Y_WIDTH-1:0] expy;
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wire [7:0] expi;
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wire [AGE_WIDTH-1:0] expi;
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// whether this pixel needs to be stored back in exposure buffer
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// whether this pixel needs to be stored back in exposure buffer
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wire exposed;
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wire exposed;
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// whether this pixel belongs to the next (backbuffer) scanline
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wire rowmatch;
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// addresses for exposure buffer read and write ports
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// addresses for exposure buffer read and write ports
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reg [HIST_WIDTH-1:0] exprptr=0, expwptr=0;
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reg [HIST_WIDTH-1:0] exprptr=0, expwptr=0;
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// scanline pixel buffers, store intensity
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// scanline pixel buffers, store intensity
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// double-buffered; one gets wiped as it is displayed
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// double-buffered; one gets wiped as it is displayed
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reg bufsel = 0;
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reg bufsel = 0;
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// address lines for scanline buffers
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// address lines for scanline buffers
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wire [X_WIDTH-1:0] sl0w, sl1w;
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wire [X_WIDTH-1:0] sl0w, sl1w;
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// RAM read out of exposure buffer
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// RAM read out of exposure buffer
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always @(posedge clk) begin
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always @(posedge clk_i) begin
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expr<=exposures[exprptr];
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expr<=exposures[exprptr];
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if (!strobe) begin
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if (!strobe) begin
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// do not skip current read position if strobe inserts a new pixel
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// do not skip current read position if strobe inserts a new pixel
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exprptr<=exprptr+1;
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exprptr<=exprptr+1;
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end
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end
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end
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end
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// decode and mux: split fields from exposure buffer, or collect new at strobe
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// decode and mux: split fields from exposure buffer, or collect new at strobe
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assign expx = strobe?x:expr[X_WIDTH+Y_WIDTH+AGE_WIDTH-1:Y_WIDTH+AGE_WIDTH];
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assign expx = strobe_i?x_i:expr[X_WIDTH+Y_WIDTH+AGE_WIDTH-1:Y_WIDTH+AGE_WIDTH];
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assign expy = strobe?y:expr[Y_WIDTH+AGE_WIDTH-1:AGE_WIDTH];
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assign expy = strobe_i?y_i:expr[Y_WIDTH+AGE_WIDTH-1:AGE_WIDTH];
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assign expi = strobe?(2**AGE_WIDTH)-1:expr[AGE_WIDTH-1:0];
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assign expi = strobe_i?(2**AGE_WIDTH)-1:expr[AGE_WIDTH-1:0];
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// detect whether pixel even needs to be stored back
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// detect whether pixel even needs to be stored back
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assign exposed = expi!=0;
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assign exposed = expi!=0;
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// detect whether pixel applies to current backbuffer
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// TODO: use a next line input port, this incrementer won't work for
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// line 0 (which is unused in display.vhd) and could be shared.
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assign rowmatch=(expy==y_i+1);
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always @(posedge clk) begin
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always @(posedge clk_i) begin
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// Feed incoming exposures into exposure buffer
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// Feed incoming exposures into exposure buffer
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if (exposed) begin
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if (exposed) begin
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exposures[expwptr] <= {expx, expy, expy==yout?expi-1:expi};
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exposures[expwptr] <= {expx, expy, expy==yout_i?expi-1:expi};
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expwptr <= expwptr+1;
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expwptr <= expwptr+1;
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end
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end
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end
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end
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// scanline buffers switch output or expose roles based on bufsel
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// scanline buffers switch output or expose roles based on bufsel
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assign sl0w=bufsel?expx:xout;
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assign sl0w=bufsel?expx:xout_i;
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assign sl1w=bufsel?xout:expx;
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assign sl1w=bufsel?xout_i:expx;
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always @(posedge clk) begin
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always @(posedge clk_i) begin
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// Read out front buffer
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// Read out front buffer
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pixelout <= bufsel?scanline1[sl1w]:scanline0[sl0w];
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pixelout <= bufsel?scanline1[xout_i]:scanline0[xout_i];
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// TODO: use a next line input port, this incrementer won't work for
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// line 0 (which is unused in display.vhd) and could be shared.
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// Store exposures for next scanline and wipe front buffer
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if (expy==(y+1)) begin
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if (bufsel) begin
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// Store exposures for current scanline and wipe front buffer
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if (rowmatch)
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scanline0[sl0w] <= bufsel?expi:0;
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scanline0[sl0w] <= expi;
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scanline1[sl1w] <= bufsel?0:expi;
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scanline1[sl1w] <= 0;
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end else begin
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if (rowmatch)
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scanline1[sl1w] <= expi;
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scanline0[sl0w] <= 0;
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end
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end
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// swap buffers when signaled
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// swap buffers when signaled
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if (newline) begin
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if (newline_i) begin
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bufsel <= ~bufsel;
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bufsel <= ~bufsel;
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end
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end
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end
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end
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// output pixel intensity
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// output pixel intensity
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assign pixel = pixelout;
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assign pixel_o = pixelout;
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endmodule
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endmodule
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