Preliminary zoom support

Author: Daniel Cliche

README.md

@@ -82,6 +82,8 @@ The following video modes are available:
 
 By default, the video mode is `vga`.
 
+For a 2x zoom, add `2x` at the end of the video mode (for example: `480p2x`).
+
 ## System Simulation
 
 ```bash

rtl/sim/Makefile

@@ -38,7 +38,7 @@ clean:
 	rm -rf obj_dir
 
 sim: top.sv sim_main.cpp $(PROGRAM)
-	$(VERILATOR) -cc --exe $(CFLAGS) $(LDFLAGS) --trace --top-module top -DVIDEO top.sv sdl_ps2.cpp sim_main.cpp -I.. -I../riscv -I../usb -I../../external/graphite/rtl $(SRC) -Wno-PINMISSING -Wno-WIDTH -Wno-CASEINCOMPLETE -Wno-TIMESCALEMOD -Wno-NULLPORT -Wno-MULTIDRIVEN -Wno-UNOPTFLAT
+	$(VERILATOR) -cc --exe $(CFLAGS) $(LDFLAGS) --trace --top-module top -DVIDEO -DVIDEO_480P -DZOOM top.sv sdl_ps2.cpp sim_main.cpp -I.. -I../riscv -I../usb -I../../external/graphite/rtl $(SRC) -Wno-PINMISSING -Wno-WIDTH -Wno-CASEINCOMPLETE -Wno-TIMESCALEMOD -Wno-NULLPORT -Wno-MULTIDRIVEN -Wno-UNOPTFLAT
 	$(MAKE) -j 4 -C obj_dir -f Vtop.mk
 
 run: sim

rtl/sim/sim_main.cpp

@@ -24,8 +24,12 @@ const int screen_width = 1024;
 const int screen_height = 768;
 
 // 640x480
-const int vga_width = 800;
-const int vga_height = 525;
+//const int vga_width = 800;
+//const int vga_height = 525;
+
+// 848x480
+const int vga_width = 1088;
+const int vga_height = 517;
 
 double sc_time_stamp()
 {

rtl/soc_top.sv

@@ -406,8 +406,13 @@ module soc_top #(
 
     graphite #(
         .FB_ADDRESS(DEFAULT_FB_ADDRESS >> 'd1),
+    `ifdef ZOOM
+        .FB_WIDTH(H_RES/2),
+        .FB_HEIGHT(V_RES/2)
+    `else
         .FB_WIDTH(H_RES),
         .FB_HEIGHT(V_RES)
+    `endif
     ) graphite(
         .clk(clk_cpu),
         .reset_i(~rst_n),
@@ -449,7 +454,11 @@ module soc_top #(
 `endif // PS2_KBD
 `ifdef VIDEO
         (iowadr == 8) ? {31'b0, graphite_cmd_axis_tready} :
+`ifdef ZOOM
+        (iowadr == 9) ? {16'(H_RES/2), 16'(V_RES/2)} :
+`else // ZOOM
         (iowadr == 9) ? {16'(H_RES), 16'(V_RES)} :
+`endif // ZOOM
         (iowadr == 10) ? fb_addr :
         (iowadr == 11) ? {31'b0, vga_vsync} :
 `else // VIDEO
@@ -677,6 +686,19 @@ module soc_top #(
       .Reset(),
       .RPReset()
     );
+
+`ifdef ZOOM
+    logic [10:0] col_counter = 11'd0;
+    logic [10:0] line_counter = 11'd0;
+    logic [19:0] line_vidadr = 20'd0;
+    logic        line_dup;
+
+    logic end_of_frame, end_of_line;
+    assign end_of_frame = line_counter == V_RES - 1;
+    assign end_of_line = col_counter == 11'(H_RES / 32 - 1);
+    assign line_dup = end_of_line && !line_counter[0];
+`endif
+
 `endif // VIDEO
 
     logic nop;
@@ -694,8 +716,27 @@ module soc_top #(
 `ifdef VIDEO
             2'b10: begin
                 crw <= 1'b0;	// VGA read
+`ifdef ZOOM
+                if (col_counter == 11'd0)
+                    line_vidadr <= vidadr;
+
+                if (end_of_line) begin
+                    col_counter <= 11'd0;
+                    line_counter <= line_counter + 11'd1;
+                end else begin
+                    col_counter <= col_counter + 11'd1;
+                end
+                if (end_of_frame && end_of_line) begin
+                    vidadr <= 20'd0;
+                    col_counter <= 11'd0;
+                    line_counter <= 11'd0;
+                end else begin
+                    vidadr <= line_dup ? line_vidadr : vidadr + 20'd1;
+                end
+`else // ZOOM
                 if(vidadr == 20'(H_RES*V_RES*2/32-1)) vidadr <= 20'd0;
                 else vidadr <= vidadr + 20'b1;
+`endif // ZOOM
             end
 `endif // VIDEO
             2'b01, 2'b11: crw <= 1'b1;	// cache read/write			

rtl/ulx3s/Makefile

@@ -53,17 +53,21 @@ DEFINES =
 ifneq (,$(findstring v,$(CONF)))
   DEFINES += -DVIDEO
 
-  ifeq ($(VIDEO),480p)
+  ifneq (,$(findstring 480p,$(VIDEO)))
   DEFINES += -DVIDEO_480P
   endif
 
-  ifeq ($(VIDEO),720p)
+  ifneq (,$(findstring 720p,$(VIDEO)))
   DEFINES += -DVIDEO_720P
   endif
 
-  ifeq ($(VIDEO),1080p)
+  ifneq (,$(findstring 1080p,$(VIDEO)))
   DEFINES += -DVIDEO_1080P
   endif
+
+  ifneq (,$(findstring 2x,$(VIDEO)))
+    DEFINES += -DZOOM
+  endif
 endif
 
 ifneq (,$(findstring k,$(CONF)))

rtl/video.v

@@ -60,20 +60,28 @@ assign hend = (hcnt == H_TOTAL-1), vend = (vcnt == V_TOTAL-1);
 assign vblank = (vcnt >= V_RES);
 assign hsync = (hcnt >= H_RES+H_FP) & (hcnt < H_RES+H_FP+H_BP);
 assign vsync = (vcnt >= V_RES+V_FP) & (vcnt < V_RES+V_FP+V_BP);
-assign xfer = hcnt[0];  // data delay > hcnt cycle + req cycle
+`ifdef ZOOM
+assign xfer = hcnt[1:0] == 2'b11;
+`else
+assign xfer = hcnt[0];
+`endif
 assign vid = (~hblank & ~vblank) ? pixbuf[15:0] : 16'd0;
 assign RGB = vid;
 
 always @(posedge pclk) if(ce && init_req_counter == 2'd0) begin  // pixel clock domain
   hcnt <= hend ? 0 : hcnt+1;
   vcnt <= hend ? (vend ? 0 : (vcnt+1)) : vcnt;
   hblank <= xfer ? (hcnt >= H_RES) : hblank;
+`ifdef ZOOM
+  pixbuf <= hcnt[1] ? vidbuf : {pixbuf[31:16], pixbuf[31:16]};
+`else
   pixbuf <= xfer ? vidbuf : {16'd0, pixbuf[31:16]};
+`endif
 end
 
 always @(posedge pclk) if(ce) begin  // CPU (SRAM) clock domain
   if (init_req_counter == 2'd0) begin
-    hword <= hcnt[0];
+    hword <= xfer;
     req <= ~vblank & (hcnt < H_RES) & hword;  // i.e. adr changed
     vidbuf <= req ? viddata : vidbuf;
   end else begin