build/sim/dut_tb: add bottom line on surface to show frame count

diff --git a/litex/build/sim/dut_tb.cpp b/litex/build/sim/dut_tb.cpp
index e5bf8b1fdc4a687dff7d706f7814a00bc79a19d6..8d0791befc827f2d82128fc21de05999f4787cbf 100644 (file)
--- a/litex/build/sim/dut_tb.cpp
+++ b/litex/build/sim/dut_tb.cpp
@@ -207,7 +207,7 @@ void vga_set_pixel(SDL_Surface *screen, int x, int y, char r, char g, char b)
 
 int vga_init(struct sim *s) {
        if(SDL_Init(SDL_INIT_VIDEO) < 0) return 1;
-       if(!(screen = SDL_SetVideoMode(640, 480, 32, SDL_HWSURFACE))) {
+       if(!(screen = SDL_SetVideoMode(640, 480+1, 32, SDL_HWSURFACE))) {
                SDL_Quit();
                return 1;
        }
@@ -216,10 +216,12 @@ int vga_init(struct sim *s) {
 
 int x;
 int y;
+int frame;
 int hsync_wait_de = 1;
 int vsync_wait_de = 1;
 
 void vga_service(struct sim *s) {
+       int i;
        if(VGA_HSYNC == 1 && hsync_wait_de == 0) {
                x = 0;
                y++;
@@ -228,6 +230,9 @@ void vga_service(struct sim *s) {
        if(VGA_VSYNC == 1 && vsync_wait_de == 0) {
                y = 0;
                vsync_wait_de = 1;
+               for(i=0; i<frame; i++)
+                       vga_set_pixel(screen, i%640, 480, 255, 255, 255);
+               frame++;
                if(SDL_MUSTLOCK(screen))
                        SDL_UnlockSurface(screen);
                SDL_Flip(screen);