Document FRLG-unique vars in main.c

src/main.c

@@ -67,9 +67,15 @@ IntrFunc gIntrTable[INTR_COUNT];
 bool8 gLinkVSyncDisabled;
 u32 IntrMain_Buffer[0x200];
 u8 gPcmDmaCounter;
-u8 gUnknown_3003578;
-u8 gUnknown_3003D80;
-u8 gUnknown_3003D84;
+
+// These variables are not defined in RS or Emerald, and are never read.
+// They were likely used to debug the audio engine and VCount interrupt.
+// Define NDEBUG in include/config.h to remove these variables.
+#ifndef NDEBUG
+u8 sVcountAfterSound;
+u8 sVcountAtIntr;
+u8 sVcountBeforeSound;
+#endif
 
 static IntrFunc * const sTimerIntrFunc = gIntrTable + 0x7;
 
@@ -369,11 +375,15 @@ static void VBlankIntr(void)
 
     gPcmDmaCounter = gSoundInfo.pcmDmaCounter;
 
-    gUnknown_3003D84 = REG_VCOUNT;
+#ifndef NDEBUG
+    sVcountBeforeSound = REG_VCOUNT;
+#endif
     m4aSoundMain();
-    gUnknown_3003578 = REG_VCOUNT;
+#ifndef NDEBUG
+    sVcountAfterSound = REG_VCOUNT;
+#endif
 
-    sub_800DD28();
+    TryReceiveLinkBattleData();
     Random();
     UpdateWirelessStatusIndicatorSprite();
 
@@ -398,7 +408,9 @@ static void HBlankIntr(void)
 
 static void VCountIntr(void)
 {
-    gUnknown_3003D80 = REG_VCOUNT;
+#ifndef NDEBUG
+    sVcountAtIntr = REG_VCOUNT;
+#endif
     m4aSoundVSync();
     INTR_CHECK |= INTR_FLAG_VCOUNT;
     gMain.intrCheck |= INTR_FLAG_VCOUNT;