From dbb61a0a339306be380ff4b3bffad64b7e474d24 Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Wed, 28 Apr 2021 19:45:09 +0200
Subject: Update main function to use the BIOS VSync

---
 src/common.h | 5 +++++
 src/irs.s    | 6 +++---
 src/main.c   | 6 +++---
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/src/common.h b/src/common.h
index dac48ad..7695683 100644
--- a/src/common.h
+++ b/src/common.h
@@ -516,4 +516,9 @@ irq_init() {
     IRQ_CTRL = 1;
 }
 
+// Stub function pointer needed for when we want to enable interrupts that don't
+// require a custom function, such as for the BIOS VSync.
+void
+irq_stub() {}
+
 #endif // GBAEXP_COMMON_H
diff --git a/src/irs.s b/src/irs.s
index 924441e..66ac0c2 100644
--- a/src/irs.s
+++ b/src/irs.s
@@ -47,7 +47,9 @@ irs_main_handle_irs:
     mov r0, #1
     lsl r0, r0, r3
     strh r0, [ip, #2]
-    @ TODO: IRQ_ACK_BIOS
+    ldr  r1, [ip, #-0x208]
+    orr  r1, r1, r0
+    str  r1, [ip, #-0x208]
 
     @ Store the SPSR in one of the free registers and save it along with the
     @ return pointer.
@@ -84,5 +86,3 @@ irs_main_exit:
 
 mem_irq_base_reg:
     .word 0x04000200 @ IRQ_ENABLE
-    .word 0x04000202 @ IRQ_ACK
-    .word 0x04000208 @ IRQ_CTRL
diff --git a/src/main.c b/src/main.c
index 6073a6a..2f1c522 100644
--- a/src/main.c
+++ b/src/main.c
@@ -44,12 +44,12 @@ int main(void) {
 
     // Register interrupts.
     irq_init();
+    irs_set(IRQ_VBLANK, irq_stub);
     irs_set(IRQ_HBLANK, irs_hblank_func);
 
     int frame_counter = 0;
     while(true) {
-        // bios_vblank_wait();
-        wait_vsync();
+        bios_vblank_wait();
         poll_keys();
 
         txt_position(0, 1);
@@ -59,7 +59,7 @@ int main(void) {
         txt_printf(" Frame counter: %d", frame_counter);
 
         frame_counter++;
-        // update_button_sprites();
+        update_button_sprites();
     };
 
     return 0;
-- 
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