Add function perform vsync

1 files changed, 13 insertions, 0 deletions

diff --git a/src/main.c b/src/main.c
index c49ce51..ea43821 100644
--- a/src/main.c
+++ b/src/main.c
@@ -20,6 +20,11 @@
 // Display modes.
 //
 
+// Display registers.
+#define DISP_CONTROL *((vu32*)(MEM_IO + 0x0000))
+#define DISP_STATUS  *((vu32*)(MEM_IO + 0x0004))
+#define DISP_VCOUNT  *((vu32*)(MEM_IO + 0x0006))
+
 // Display modes.
 #define DISP_MODE_0 0x0000
 #define DISP_MODE_1 0x0001
@@ -55,6 +60,7 @@ typedef u16 Color;
 //
 typedef Color Scanline[SCREEN_WIDTH];
 #define FRAMEBUFFER ((Scanline*)MEM_VRAM)
+#define SCREEN_BUFFER ((vu16*) MEM_VRAM)
 
 //
 // Colors.
@@ -86,6 +92,12 @@ put_line(int x, int y, Color clr, char *msg) {
     }
 }
 
+static inline void
+wait_vsync() {
+    while(DISP_VCOUNT >= 160);
+    while(DISP_VCOUNT < 160);
+}
+
 //
 // Main functions.
 //
@@ -94,6 +106,7 @@ int main(void) {
     set_display_mode(DISP_MODE_3 | DISP_BG2);
 
     while(true) {
+        wait_vsync();
         put_line(16,  20 + 16, rgb15(28, 0, 0), "Hello world from the GBA!");
         put_line(16,  20 + 32, rgb15(0, 28, 28), "Using my little 8x8 bd-font");
         put_line(16,  20 + 64, rgb15(16, 0, 28), "Isn't that neat? :D");