From 8c03c20019afb3a1099c9ea90d66d2c9f10aa6ac Mon Sep 17 00:00:00 2001
From: Jeffrey Pfau <jeffrey@endrift.com>
Date: Tue, 16 Apr 2013 23:14:16 -0700
Subject: [PATCH] Implement HALT

---
 src/gba/gba-bios.c |  3 +++
 src/gba/gba-io.c   |  8 ++++++++
 src/gba/gba.c      | 27 ++++-----------------------
 src/gba/gba.h      |  2 +-
 4 files changed, 16 insertions(+), 24 deletions(-)

diff --git a/src/gba/gba-bios.c b/src/gba/gba-bios.c
index df1de54ce..4cc1f562f 100644
--- a/src/gba/gba-bios.c
+++ b/src/gba/gba-bios.c
@@ -49,6 +49,9 @@ static void _CpuSet(struct GBA* gba) {
 void GBASwi16(struct ARMBoard* board, int immediate) {
 	struct GBA* gba = ((struct GBABoard*) board)->p;
 	switch (immediate) {
+	case 0x2:
+		GBAHalt(gba);
+		break;
 	case 0xB:
 		_CpuSet(gba);
 		break;
diff --git a/src/gba/gba-io.c b/src/gba/gba-io.c
index e3739c3c5..d272bfb78 100644
--- a/src/gba/gba-io.c
+++ b/src/gba/gba-io.c
@@ -41,6 +41,14 @@ void GBAIOWrite(struct GBA* gba, uint32_t address, uint16_t value) {
 	case REG_IME:
 		GBAWriteIME(gba, value);
 		break;
+	case REG_HALTCNT:
+		value &= 0x80;
+		if (!value) {
+			GBAHalt(gba);
+		} else {
+			GBALog(GBA_LOG_STUB, "Stop unimplemented");
+		}
+		return;
 	default:
 		GBALog(GBA_LOG_STUB, "Stub I/O register write: %03x", address);
 		break;
diff --git a/src/gba/gba.c b/src/gba/gba.c
index b2b18a63d..6d305bb9b 100644
--- a/src/gba/gba.c
+++ b/src/gba/gba.c
@@ -130,12 +130,6 @@ void GBARaiseIRQ(struct GBA* gba, enum GBAIRQ irq) {
 	}
 }
 
-void GBAPollNextEvent(struct GBA* gba) {
-	int32_t nextEvent = gba->video.nextEvent;
-
-	gba->cpu.nextEvent = nextEvent;
-}
-
 int GBATestIRQ(struct GBA* gba) {
 	if (gba->memory.io[REG_IME >> 1] && gba->memory.io[REG_IE >> 1] & gba->memory.io[REG_IF >> 1]) {
 		gba->springIRQ = 1;
@@ -146,24 +140,7 @@ int GBATestIRQ(struct GBA* gba) {
 }
 
 int GBAWaitForIRQ(struct GBA* gba) {
-	int irqPending = GBATestIRQ(gba) || gba->video.hblankIRQ || gba->video.vblankIRQ || gba->video.vcounterIRQ;
-	/*if (this.timersEnabled) {
-		timer = this.timers[0];
-		irqPending = irqPending || timer.doIrq;
-		timer = this.timers[1];
-		irqPending = irqPending || timer.doIrq;
-		timer = this.timers[2];
-		irqPending = irqPending || timer.doIrq;
-		timer = this.timers[3];
-		irqPending = irqPending || timer.doIrq;
-	}*/
-	if (!irqPending) {
-		return 0;
-	}
-
 	while (1) {
-		GBAPollNextEvent(gba);
-
 		if (gba->cpu.nextEvent == INT_MAX) {
 			return 0;
 		} else {
@@ -176,6 +153,10 @@ int GBAWaitForIRQ(struct GBA* gba) {
 	}
 }
 
+int GBAHalt(struct GBA* gba) {
+	return GBAWaitForIRQ(gba);
+}
+
 void GBALog(int level, const char* format, ...) {
 	va_list args;
 	va_start(args, format);
diff --git a/src/gba/gba.h b/src/gba/gba.h
index 9579c58a1..c1426b031 100644
--- a/src/gba/gba.h
+++ b/src/gba/gba.h
@@ -64,9 +64,9 @@ void GBABoardReset(struct ARMBoard* board);
 void GBAWriteIE(struct GBA* gba, uint16_t value);
 void GBAWriteIME(struct GBA* gba, uint16_t value);
 void GBARaiseIRQ(struct GBA* gba, enum GBAIRQ irq);
-void GBAPollNextEvent(struct GBA* gba);
 int GBATestIRQ(struct GBA* gba);
 int GBAWaitForIRQ(struct GBA* gba);
+int GBAHalt(struct GBA* gba);
 
 void GBAAttachDebugger(struct GBA* gba, struct ARMDebugger* debugger);