[nostalgia/core/gba] Add sprite support

src/nostalgia/core/gba/irq.arm.cpp

@@ -9,10 +9,35 @@
 // NOTE: this file is compiled as ARM and not THUMB, so don't but too much in
 // here
 
+#include <nostalgia/core/config.hpp>
+
+#include "addresses.hpp"
+#include "gfx.hpp"
 #include "irq.hpp"
 
+namespace nostalgia::core {
+
+volatile uint16_t g_spriteUpdates = 0;
+GbaSpriteAttrUpdate g_spriteBuffer[config::GbaSpriteBufferLen];
+
+}
+
+using namespace nostalgia::core;
+
 extern "C" {
 
+void nostalgia_core_isr_vblank() {
+	// copy g_spriteUpdates to allow it to use a register instead of reading
+	// from memory every iteration of the loop, needed because g_spriteUpdates
+	// is volatile
+	const auto updates = g_spriteUpdates;
+	for (uint16_t i = 0; i < updates; ++i) {
+		auto &oa = g_spriteBuffer[i];
+		MEM_OAM[oa.idx] = *reinterpret_cast<uint64_t*>(&oa);
+	}
+	g_spriteUpdates = 0;
+}
+
 void nostalgia_core_isr_timer0() {
 }
 
@@ -25,7 +50,4 @@ void nostalgia_core_isr_timer2() {
 void nostalgia_core_isr_timer3() {
 }
 
-void nostalgia_core_isr_vblank() {
-}
-
 }