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-rw-r--r--display.v245
1 files changed, 140 insertions, 105 deletions
diff --git a/display.v b/display.v
index 81886b7..68c5be0 100644
--- a/display.v
+++ b/display.v
@@ -1,18 +1,20 @@
module display (
- input clk, // 18.75 MHz
-
+ input clk, // 18.75 MHz
+
input width,
input reverse,
input noblink,
input testpattern,
input reveal,
-
+
output reg [10:0] a,
input [7:0] d,
output [10:0] ga,
input [5:0] gd,
+ output [12:0] bga,
+ input [5:0] bgd,
- output reg [2:0] rgb,
+ output reg [5:0] rgb,
output vsync,
output hsync,
@@ -38,7 +40,7 @@ module display (
// 30 pixels ( 5 char) front porch
// ----------
// 594 pixels (31.68 us)
-//
+//
// Vertical:
// 480 lines graphics (24 rows x 10 pixels x 2 scans/pixel)
// 10 lines back porch/border
@@ -59,101 +61,108 @@ module display (
// especially the desired aspect ratio. Therefore, we want to use -hsync
// and -vsync, - meaning active low, + meaning active high.
- parameter x_blank = 480+6;
- parameter x_sync = x_blank+(12-6);
- parameter x_front = x_sync+72;
- parameter x_max = 594;
-
- parameter y_blank = 480;
- parameter y_sync = y_blank+10;
- parameter y_front = y_sync+2;
- parameter y_max = 525;
-
- parameter hsync_minus = 1'b1; // -hsync
- parameter vsync_minus = 1'b1; // -vsync
-
- reg hsync_q; // Horizontal sync active
- reg vsync_q; // Vertical sync active
-
- reg [9:0] x; // Horizontal pixel count
- reg [9:0] y; // Vertical pixel count
- reg [6:0] xchr; // Character column (0..99)
- reg [2:0] xpxl; // Pixel column in character (0..5)
- reg [4:0] ychr; // Character row (0..26)
- reg [3:0] ypxl; // Pixel row in character (0..9)
- reg [4:0] ylu; // Previous character line
-
- wire xvideo; // Non-blanked in the x direction
- wire yvideo; // Non-blanked in the y direction
- wire [10:0] a80; // Memory address assuming 80 columns
- wire [10:0] a80u; // Memory address assuming 80 columns (-1 line)
- wire [10:0] a40; // Memory address assuming 40 columns
- wire [10:0] a40u; // Memory address assuming 40 columns (-1 line)
- reg [4:0] scan_counter; // Counter of total scans (for flashing et al)
- reg [5:0] pixrow; // One character worth of pixels
- reg prefetch; // True for the prefetch character position
+ parameter x_blank = 480+6;
+ parameter x_sync = x_blank+(12-6);
+ parameter x_front = x_sync+72;
+ parameter x_max = 594;
+
+ parameter y_blank = 480;
+ parameter y_sync = y_blank+10;
+ parameter y_front = y_sync+2;
+ parameter y_max = 525;
+
+ parameter hsync_minus = 1'b1; // -hsync
+ parameter vsync_minus = 1'b1; // -vsync
+
+ reg hsync_q; // Horizontal sync active
+ reg vsync_q; // Vertical sync active
+
+ reg [9:0] x; // Horizontal pixel count
+ reg [9:0] y; // Vertical pixel count
+ reg [6:0] xchr; // Character column (0..99)
+ reg [2:0] xpxl; // Pixel column in character (0..5)
+ reg [4:0] ychr; // Character row (0..26)
+ reg [3:0] ypxl; // Pixel row in character (0..9)
+ wire [3:0] ypxlp = ypxl + 4'd1; // d:o but 1..10
+ reg [4:0] ylu; // Previous character line
+
+ wire xvideo; // Non-blanked in the x direction
+ wire yvideo; // Non-blanked in the y direction
+ wire [10:0] a80; // Memory address assuming 80 columns
+ wire [10:0] a80u; // Memory address assuming 80 columns (-1 line)
+ wire [10:0] a40; // Memory address assuming 40 columns
+ wire [10:0] a40u; // Memory address assuming 40 columns (-1 line)
+ reg [4:0] scan_counter; // Counter of total scans (for flashing et al)
+ reg [5:0] pixrow; // One character worth of pixels
+ reg prefetch; // True for the prefetch character position
// Fine Graphics control
- reg [7:0] fgctl_q; // Latched version of fg_ctl
- reg [7:0] fgpixels; // One byte of fg pixels
-
+ reg [7:0] fgctl_q; // Latched version of fg_ctl
+ reg [7:0] fgpixels; // One byte of fg pixels
+
+ // Block graphics data
+ reg [5:0] block_rgb; // Current block graphics pixel
+ reg [6:0] block_x; // Block graphics pixel X
+ reg [2:0] block_xpxl; // Physical pixel inside block
+ // We leverage ychr and ypxl for the vertical
+
// For the current text line
- reg [2:0] curfg; // Foreground RGB
- reg [2:0] curbg; // Background RGB
- reg inverse; // Inverse video
- reg isgraph; // Graphic mode?
- reg isgsep; // Separated graphics?
- reg isgrel; // Hold graphics?
- reg isdble; // Double height?
- reg isflsh; // Flashing?
- reg ishide; // Hidden
- reg [7:0] thischar; // Character code currently processing
+ reg [2:0] curfg; // Foreground RGB
+ reg [2:0] curbg; // Background RGB
+ reg inverse; // Inverse video
+ reg isgraph; // Graphic mode?
+ reg isgsep; // Separated graphics?
+ reg isgrel; // Hold graphics?
+ reg isdble; // Double height?
+ reg isflsh; // Flashing?
+ reg ishide; // Hidden
+ reg [7:0] thischar; // Character code currently processing
// These refer to the same as above, but for the previous text line
- reg [2:0] oldfg; // Foreground RGB
- reg [2:0] oldbg; // Background RGB
- reg wasgraph; // Graphic mode?
- reg wasgsep; // Separated graphics?
- reg wasgrel; // Hold graphics?
- reg wasdble; // Double height?
- reg wasflsh; // Flashing?
- reg washide; // Hidden
- reg [7:0] thatchar; // Character code currently processing
+ reg [2:0] oldfg; // Foreground RGB
+ reg [2:0] oldbg; // Background RGB
+ reg wasgraph; // Graphic mode?
+ reg wasgsep; // Separated graphics?
+ reg wasgrel; // Hold graphics?
+ reg wasdble; // Double height?
+ reg wasflsh; // Flashing?
+ reg washide; // Hidden
+ reg [7:0] thatchar; // Character code currently processing
// The one we're currently displaying
- wire [2:0] fg = wasdble ? oldfg : curfg;
- wire [2:0] bg = wasdble ? oldbg : curbg;
- wire [7:0] somechar = wasdble ? thatchar : thischar;
+ wire [2:0] fg = wasdble ? oldfg : curfg;
+ wire [2:0] bg = wasdble ? oldbg : curbg;
+ wire [7:0] somechar = wasdble ? thatchar : thischar;
wire gsep = wasdble ? wasgsep : isgsep;
- wire do_flsh = wasdble ? wasflsh : isflsh;
- wire do_hide = wasdble ? washide : ishide;
+ wire do_flsh = wasdble ? wasflsh : isflsh;
+ wire do_hide = wasdble ? washide : ishide;
// Should we advance the character pixel?
// We need to always advance at full speed during prefetch, or
// we would have to start the prefetch earlier in 40-character mode.
- wire advance = width | x[0] | prefetch;
-
+ wire advance = width | x[0] | prefetch;
+
// Address mapping for 40 and 80 characters
- assign a80[3:0] = xchr[3:0];
- wire [3:0] x80middle = { 1'b0, xchr[6:4] };
- wire [3:0] ymiddle = { ychr[4:3] , ychr[4:3] };
- assign a80[7:4] = x80middle+ymiddle;
- assign a80[10:8] = ychr[2:0];
+ assign a80[3:0] = xchr[3:0];
+ wire [3:0] x80middle = { 1'b0, xchr[6:4] };
+ wire [3:0] ymiddle = { ychr[4:3] , ychr[4:3] };
+ assign a80[7:4] = x80middle+ymiddle;
+ assign a80[10:8] = ychr[2:0];
assign a40[2:0] = xchr[2:0];
- wire [3:0] x40middle = { 1'b0, xchr[5:3] };
- assign a40[6:3] = x40middle + ymiddle;
- assign a40[10:7] = { 1'b1, ychr[2:0] };
+ wire [3:0] x40middle = { 1'b0, xchr[5:3] };
+ assign a40[6:3] = x40middle + ymiddle;
+ assign a40[10:7] = { 1'b1, ychr[2:0] };
// Address mapping for 40 and 80 characters minus one line
- assign a80u[3:0] = xchr[3:0];
- wire [3:0] yumiddle = { ylu[4:3] , ylu[4:3] };
- assign a80u[7:4] = x80middle+yumiddle;
- assign a80u[10:8] = ylu[2:0];
+ assign a80u[3:0] = xchr[3:0];
+ wire [3:0] yumiddle = { ylu[4:3] , ylu[4:3] };
+ assign a80u[7:4] = x80middle+yumiddle;
+ assign a80u[10:8] = ylu[2:0];
- assign a40u[2:0] = xchr[2:0];
- assign a40u[6:3] = x40middle+yumiddle;
- assign a40u[10:7] = { 1'b1, ylu[2:0] };
+ assign a40u[2:0] = xchr[2:0];
+ assign a40u[6:3] = x40middle+yumiddle;
+ assign a40u[10:7] = { 1'b1, ylu[2:0] };
// Final address mapping
// Note: We read the current char between pixels 0 and 1,
@@ -170,35 +179,42 @@ module display (
a = a80u;
endcase // case( { width, xchr[1] } )
+ // Block graphics address mapping
+ assign bga[3:0] = block_x[3:0];
+ wire [3:0] bgxmiddle = { 1'b0, block_x[6:4] };
+ wire [3:0] bgymiddle = { ypxlp[3:2], ypxlp[3:2] };
+ assign bga[7:4] = bgxmiddle + bgymiddle;
+ assign bga[12:8] = ychr;
+
// Character generator address mapping
- assign ga[10:4] = somechar[6:0];
- assign ga[3:0] = wasdble ? { 1'b1, ypxl[3:1] } :
+ assign ga[10:4] = somechar[6:0];
+ assign ga[3:0] = wasdble ? { 1'b1, ypxl[3:1] } :
isdble ? { 1'b0, ypxl[3:1] } :
ypxl[3:0];
// Video enable signal
- assign xvideo = ( x < x_blank );
- assign yvideo = ( y < y_blank );
+ assign xvideo = ( x < x_blank );
+ assign yvideo = ( y < y_blank );
+
+ assign hsync = hsync_q ^ hsync_minus;
+ assign vsync = vsync_q ^ vsync_minus;
- assign hsync = hsync_q ^ hsync_minus;
- assign vsync = vsync_q ^ vsync_minus;
-
// Flashing
- wire flash_on = scan_counter[4];
+ wire flash_on = scan_counter[4];
// Inverse video. The normal is a flashing inverse cursor, but
// if "noblink" is asserted the cursor is steady inverted. If
// "reverse" is asserted with invert everything *on top of that*...
- wire invert = (inverse & (flash_on|noblink))^reverse;
+ wire invert = (inverse & (flash_on|noblink))^reverse;
//
// Fine graphics
//
- assign fg_ack = xvideo & yvideo & (x[2:0] == 3'b000);
- assign fg_xrst = yvideo & hsync_q;
- assign fg_yrst = vsync_q;
+ assign fg_ack = xvideo & yvideo & (x[2:0] == 3'b000);
+ assign fg_xrst = yvideo & hsync_q;
+ assign fg_yrst = vsync_q;
- wire [3:0] fg_argb;
+ wire [3:0] fg_argb;
always @(posedge clk)
if ( ~yvideo ) // Only change mode during vertical blank
@@ -215,35 +231,37 @@ module display (
.clock ( clk ),
.q ( fg_argb )
);
-
+
// Synchronous logic
always @(posedge clk)
begin
if ( ~xvideo | ~yvideo | prefetch )
- rgb <= 3'b000; // Blank
+ rgb <= 6'b000000; // Blank
else if ( testpattern )
// Pixel test pattern for LCD monitor calibration
- rgb <= {3{x[0] ^ y[0]}};
+ rgb <= {6{x[0] ^ y[0]}} ^ {6{invert}};
else if ( ~fgctl_q[7] & pixrow[5]
& ~(do_flsh & ~flash_on)
& ~(do_hide & ~reveal) )
- rgb <= fg ^ {3{invert}};
+ rgb <= {fg[2],fg[2],fg[1],fg[1],fg[0],fg[0]} ^ {6{invert}};
else if (fgctl_q[7] | fg_argb[3])
- rgb <= fg_argb[2:0];
+ rgb <= {fg_argb[2],fg_argb[2],fg_argb[1],fg_argb[1],fg_argb[0],fg_argb[0]} ^ {6{invert}};
+ else if (bg == 3'b000)
+ rgb <= block_rgb ^ {6{invert}};
else
- rgb <= bg ^ {3{invert}};
+ rgb <= {bg[2],bg[2],bg[1],bg[1],bg[0],bg[0]} ^ {6{invert}};
// Sync pulses
vsync_q <= ( y >= y_sync && y < y_front );
hsync_q <= ( x >= x_sync && x < x_front );
-
+
// Rotating shift register; may be overridden by the below
// The rotation is so that if we're in GHOL mode we already
// have the previous value
if ( advance )
pixrow <= { pixrow[4:0], pixrow[5] };
-
+
// This code is run 6 times per character; regardless of width
if ( advance )
begin
@@ -259,7 +277,7 @@ module display (
// Load and process previous-line character
thatchar <= (ychr == 0) ? 8'h00 : d;
end
-
+
3'b101:
begin
// Load a new pixel row?
@@ -416,14 +434,22 @@ module display (
end // case: 3'b101
endcase // case( xpxl )
end // if ( advance )
-
+
+ // Block graphics - the block graphics pixels exactly match
+ // 80-column characters
+ if ( block_xpxl == 3'd5 )
+ block_rgb <= bgd;
+
// Counters
if ( x == x_max-1 )
begin
x <= 10'd0;
xchr <= 7'd0;
xpxl <= 3'd0;
+ block_x <= 7'd0;
+ block_xpxl <= 3'd0;
pixrow <= 6'b0; // Read-ahead spot is blank
+ block_rgb <= 6'b0;
prefetch <= 1'b1; // Prefetch character
inverse <= 1'b0; // Not inverse video
curfg <= 3'b111; // Default fg is white
@@ -477,6 +503,15 @@ module display (
else
xpxl <= xpxl + 1;
end
+
+ if ( block_xpxl == 3'd5 )
+ begin
+ block_xpxl <= 0;
+ block_x <= block_x + 1;
+ end
+ else
+ block_xpxl <= block_xpxl + 1;
+
x <= x + 1;
end // else: !if( x == x_max-1 )
end // always @ (posedge clk)