From 1a2831200c5e28c408c75bbbd4c14a28801c8216 Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Sat, 8 Aug 2020 21:28:55 -0700
Subject: [PATCH] GBA Hardware: Fix RTC

---
 CHANGES                              |  1 +
 include/mgba/internal/gba/hardware.h | 21 +++++++++++++--------
 src/gba/hardware.c                   | 18 +++++++++---------
 3 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/CHANGES b/CHANGES
index 6c503a44f..d12ece948 100644
--- a/CHANGES
+++ b/CHANGES
@@ -12,6 +12,7 @@ Bugfixes:
  - DS Video: Fix 2D/3D blending alpha values
  - DS I/O: Enable POWCNT1 bit 1 at boot (fixes mgba.io/i/616)
  - DS Slot-1: Reply to IR 0x08 command properly (fixes mgba.io/i/666)
+ - GBA Hardware: Fix RTC
  - GBA Video: Fix mode 2 out-of-bounds VRAM crash
  - GBA Video: Fix regression adjusting brightness of backdrop
  - DS GX: Properly reject invalid commands
diff --git a/include/mgba/internal/gba/hardware.h b/include/mgba/internal/gba/hardware.h
index a06da3a80..498334356 100644
--- a/include/mgba/internal/gba/hardware.h
+++ b/include/mgba/internal/gba/hardware.h
@@ -53,12 +53,6 @@ enum GPIODirection {
 	GPIO_READ_WRITE = 1
 };
 
-DECL_BITFIELD(RTCControl, uint8_t);
-DECL_BIT(RTCControl, Reset, 0);
-DECL_BIT(RTCControl, Hour24, 1);
-DECL_BIT(RTCControl, IRQ1, 4);
-DECL_BIT(RTCControl, IRQ2, 5);
-
 enum RTCCommand {
 	RTC_STATUS1 = 0,
 	RTC_ALARM1 = 1,
@@ -70,6 +64,17 @@ enum RTCCommand {
 	RTC_FREE_REG = 7
 };
 
+DECL_BITFIELD(RTCStatus1, uint8_t);
+DECL_BIT(RTCStatus1, Reset, 0);
+DECL_BIT(RTCStatus1, Hour24, 1);
+DECL_BIT(RTCStatus1, IRQ1, 4);
+DECL_BIT(RTCStatus1, IRQ2, 5);
+
+DECL_BITFIELD(RTCControl, uint8_t);
+DECL_BIT(RTCControl, MinIRQ, 3);
+DECL_BIT(RTCControl, Hour24, 6);
+DECL_BIT(RTCControl, Poweroff, 7);
+
 DECL_BITFIELD(RTCCommandData, uint8_t);
 DECL_BITS(RTCCommandData, Magic, 0, 4);
 DECL_BITS(RTCCommandData, Command, 4, 3);
@@ -89,9 +94,9 @@ struct GBARTC {
 	uint8_t commandActive;
 	uint8_t alarm1[3];
 	RTCCommandData command;
-	RTCStatus2 status2;
+	uint8_t status1;
 	uint8_t freeReg;
-	RTCControl control;
+	uint8_t control; // Used for status2 on DS
 	uint8_t alarm2[3];
 	uint8_t time[7];
 };
diff --git a/src/gba/hardware.c b/src/gba/hardware.c
index 54a7d565f..374132f6c 100644
--- a/src/gba/hardware.c
+++ b/src/gba/hardware.c
@@ -131,7 +131,7 @@ void GBAHardwareInitRTC(struct GBACartridgeHardware* hw) {
 	hw->rtc.command = 0;
 	hw->rtc.control = 0x40;
 	hw->rtc.freeReg = 0;
-	hw->rtc.status2 = 0;
+	hw->rtc.status1 = 0;
 	memset(hw->rtc.time, 0, sizeof(hw->rtc.time));
 }
 
@@ -245,7 +245,7 @@ void GBARTCProcessByte(struct GBARTC* rtc, struct mRTCSource* source) {
 			case RTC_FORCE_IRQ:
 				break;
 			case RTC_ALARM1:
-				if (RTCStatus2GetINT1(rtc->status2) == 4) {
+				if (RTCStatus2GetINT1(rtc->control) == 4) {
 					rtc->bytesRemaining = 3;
 				}
 			}
@@ -254,14 +254,14 @@ void GBARTCProcessByte(struct GBARTC* rtc, struct mRTCSource* source) {
 		}
 	} else {
 		switch (RTCCommandDataGetCommand(rtc->command)) {
-		case RTC_STATUS1:
-			rtc->control = rtc->bits & 0xFE;
+		case RTC_STATUS2:
+			rtc->control = rtc->bits;
 			break;
 		case RTC_FORCE_IRQ:
 			mLOG(GBA_HW, STUB, "Unimplemented RTC command %u", RTCCommandDataGetCommand(rtc->command));
 			break;
-		case RTC_STATUS2:
-			rtc->status2 = rtc->bits;
+		case RTC_STATUS1:
+			rtc->status1 = rtc->bits & 0xFE;
 			break;
 		case RTC_FREE_REG:
 			rtc->freeReg = rtc->bits;
@@ -292,10 +292,10 @@ unsigned GBARTCOutput(struct GBARTC* rtc) {
 	}
 	switch (RTCCommandDataGetCommand(rtc->command)) {
 	case RTC_STATUS1:
-		outputByte = rtc->control;
+		outputByte = rtc->status1;
 		break;
 	case RTC_STATUS2:
-		outputByte = rtc->status2;
+		outputByte = rtc->control;
 		break;
 	case RTC_DATETIME:
 	case RTC_TIME:
@@ -332,7 +332,7 @@ void _rtcUpdateClock(struct GBARTC* rtc, struct mRTCSource* source) {
 	rtc->time[1] = _rtcBCD(date.tm_mon + 1);
 	rtc->time[2] = _rtcBCD(date.tm_mday);
 	rtc->time[3] = _rtcBCD(date.tm_wday);
-	if (RTCControlIsHour24(rtc->control)) {
+	if (RTCControlIsHour24(rtc->control) || RTCStatus1IsHour24(rtc->status1)) {
 		rtc->time[4] = _rtcBCD(date.tm_hour);
 	} else {
 		rtc->time[4] = _rtcBCD(date.tm_hour % 12);