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optimized scanline renderer

This commit is contained in:
Steven Hugg 2018-02-25 10:51:09 -06:00
parent b2beb2670c
commit 6fa030f398
1 changed files with 17 additions and 27 deletions
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44
presets/verilog/sprite_scanline_renderer.v
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@ -34,7 +34,7 @@ module sprite_scanline_renderer(clk, reset, hpos, vpos, rgb,
rom_addr, rom_data);
parameter NB = 5;
parameter MB = 2;
parameter MB = 3;
localparam N = 1<<NB;
localparam M = 1<<MB;
@ -85,17 +85,13 @@ module sprite_scanline_renderer(clk, reset, hpos, vpos, rgb,
// reset every frame, don't draw vpos >= 256
if (reset || vpos[8]) begin
// initialize counters, even though it works w/o it
i <= 0;
j <= 0;
k <= 0;
// wiggle sprites randomly once per frame
if (vpos == 256 && hpos < N) begin
sprite_xpos[move_index] <= sprite_xpos[move_index] + 8'(($random&3)-1);
sprite_ypos[move_index] <= sprite_ypos[move_index] + 8'(($random&3)-1);
end
end else
if (hpos < N*2) begin
end else if (hpos < N*2) begin
k <= 0;
// select the sprites that will appear in this scanline
case (hpos[0])
// compute Y offset of sprite relative to scanline
@ -111,31 +107,22 @@ module sprite_scanline_renderer(clk, reset, hpos, vpos, rgb,
i <= i + 1; // inc main array counter
end
endcase
end else if (hpos < N*2+M*4) begin
// copy sprites from main array to local array
case (hpos[1:0])
0: i <= sprite_to_line[j];
// transfer sprite X pos to line array
1: line_xpos[j] <= sprite_xpos[i];
// transfer sprite attribte to line array
2: line_attr[j] <= sprite_attr[i];
// increment 2nd array counter
3: j <= j + 1;
endcase
end else if (hpos < N*2+M*4+M*32) begin
i <= 0;
end else if (hpos < N*2+M*24) begin
j <= 0;
if (hpos[4:0] < 16) begin
// divide hpos by 24 (8 setup + 16 render)
if ((hpos[3:0] < 8) ^^ hpos[4]) begin
// render sprites into write buffer
case (hpos[4:0])
case (hpos[3:0])
// grab index into main sprite array
0: i <= sprite_to_line[k];
// load scanline buffer offset to write
0: write_ofs <= {~vpos[0], line_xpos[k]};
// set ROM address and fetch bitmap
1: rom_addr <= {4'b0, line_attr[k][7:4], line_yofs[k]};
1: write_ofs <= {~vpos[0], sprite_xpos[i]};
// set ROM address and fetch bitmap
2: rom_addr <= {4'b0, sprite_attr[i][7:4], line_yofs[k]};
// fetch 0 if sprite is inactive
2: out_bitmap <= line_active[k] ? rom_data : 0;
3: out_bitmap <= line_active[k] ? rom_data : 0;
// load attribute for sprite
3: out_attr <= line_attr[k];
4: out_attr <= sprite_attr[i];
// disable sprite for next scanline
6: line_active[k] <= 0;
// go to next sprite in 2ndary buffer
@ -150,6 +137,9 @@ module sprite_scanline_renderer(clk, reset, hpos, vpos, rgb,
// increment to next scanline pixel
write_ofs <= write_ofs + 1;
end
end else begin
// clear counters
i <= 0;
end
// read and clear buffer