FDS: IRQs are affected by enable disk io register

negativeExponent · Jun 2, 2022 · d623a93 · d623a93
1 parent 971d721
commit d623a93
Showing 1 changed file with 16 additions and 8 deletions.
diff --git a/src/fds.cpp b/src/fds.cpp
@@ -223,8 +223,8 @@ void FCEU_FDSSelect(void)
 	FCEU_DispMessage("Disk %d Side %c Selected", 0, SelectDisk >> 1, (SelectDisk & 1) ? 'B' : 'A');
 }
 
-#define IRQ_Repeat  (IRQa & 0x01)
-#define IRQ_Enabled (IRQa & 0x02)
+#define IRQ_Repeat  0x01
+#define IRQ_Enabled 0x02
 
 static void FDSFix(int a) {
 	if ((IRQa & IRQ_Enabled) && IRQCount) {
@@ -574,21 +574,29 @@ void FDSSoundReset(void) {
 static DECLFW(FDSWrite) {
 	switch (A) {
 	case 0x4020:
-		X6502_IRQEnd(FCEU_IQEXT);
 		IRQLatch &= 0xFF00;
 		IRQLatch |= V;
 		break;
 	case 0x4021:
-		X6502_IRQEnd(FCEU_IQEXT);
 		IRQLatch &= 0xFF;
 		IRQLatch |= V << 8;
 		break;
 	case 0x4022:
-		X6502_IRQEnd(FCEU_IQEXT);
-		IRQCount = IRQLatch;
-		IRQa = V & 3;
+		IRQa &= ~1;
+		IRQa |= (V & 1);
+		if ((V & 2) && (FDSRegs[3] & 1)) {
+			IRQa |= 2;
+			IRQCount = IRQLatch;
+		} else
+			X6502_IRQEnd(FCEU_IQEXT);
+		break;
+	case 0x4023:
+		if (!(V & 1)) {
+			IRQa &= 2;
+			X6502_IRQEnd(FCEU_IQEXT);
+			X6502_IRQEnd(FCEU_IQEXT2);
+		}
 		break;
-	case 0x4023: break;
 	case 0x4024:
 		if (mapperFDS_diskinsert && ~mapperFDS_control & 0x04) {