RTC code/data

13 files changed, 614 insertions, 944 deletions

diff --git a/asm/crt0.s b/asm/crt0.s
index 9729a9488..94d4a4b7a 100644
--- a/asm/crt0.s
+++ b/asm/crt0.s
@@ -12,7 +12,7 @@ GPIOPortData: ; 80000C4
 GPIOPortDirection: ; 80000C6
 	.2byte 0
 
-GPIOPortReadWrite: ; 80000C8
+GPIOPortReadEnable: ; 80000C8
 	.2byte 0
 
 	.rept 6
diff --git a/asm/rom.s b/asm/rom.s
index 913d13834..0d916724f 100644
--- a/asm/rom.s
+++ b/asm/rom.s
@@ -27,7 +27,7 @@ AgbMain: ; 800024C
 	bl InitKeypadData
 	bl InitIntrHandlers
 	bl m4aSoundInit
-	bl GameFreakRTC_Init
+	bl RtcInit
 	bl CheckForFlashMemory
 	bl init_saveblock_ptrs_and_set_copyright_callback2
 	bl sound_sources_off
@@ -204,7 +204,7 @@ _080003E0: .4byte 0x0000043c
 	thumb_func_start SeedRngWithRtc
 SeedRngWithRtc: ; 80003E4
 	push {lr}
-	bl GameFreakRTC_GetNumMinutes
+	bl RtcGetMinuteCount
 	adds r2, r0, 0
 	lsrs r0, r2, 16
 	ldr r1, _080003FC
@@ -620,7 +620,7 @@ DoSoftReset: ; 80006B4
 	ands r2, r1
 	strh r2, [r0, 0xA]
 	ldrh r0, [r0, 0xA]
-	bl RTC_SetReadOnly
+	bl RTC_Protect
 	movs r0, 0xFF
 	bl SoftReset
 	pop {r4}
@@ -18378,803 +18378,7 @@ _080090EC: .4byte 0x00000fbc
 _080090F0: .4byte 0x0000efff
 	thumb_func_end sub_8009084
 
-	thumb_func_start GFRTC_DisableInterrupts
-GFRTC_DisableInterrupts: ; 80090F4
-	ldr r2, _08009104
-	ldr r1, _08009108
-	ldrh r0, [r1]
-	strh r0, [r2]
-	movs r0, 0
-	strh r0, [r1]
-	bx lr
-	.align 2
-_08009104: .4byte 0x0300046e
-_08009108: .4byte 0x04000208
-	thumb_func_end GFRTC_DisableInterrupts
-
-	thumb_func_start GFRTC_RestoreInterrupts
-GFRTC_RestoreInterrupts: ; 800910C
-	ldr r0, _08009118
-	ldr r1, _0800911C
-	ldrh r1, [r1]
-	strh r1, [r0]
-	bx lr
-	.align 2
-_08009118: .4byte 0x04000208
-_0800911C: .4byte 0x0300046e
-	thumb_func_end GFRTC_RestoreInterrupts
-
-	thumb_func_start GFRTC_ConvertBcdToBinary
-GFRTC_ConvertBcdToBinary: ; 8009120
-	push {lr}
-	lsls r0, 24
-	lsrs r2, r0, 24
-	cmp r2, 0x9F
-	bhi _08009132
-	movs r3, 0xF
-	ands r3, r2
-	cmp r3, 0x9
-	bls _08009136
-_08009132:
-	movs r0, 0xFF
-	b _08009144
-_08009136:
-	lsrs r1, r0, 28
-	movs r0, 0xF
-	ands r1, r0
-	lsls r0, r1, 2
-	adds r0, r1
-	lsls r0, 1
-	adds r0, r3
-_08009144:
-	pop {r1}
-	bx r1
-	thumb_func_end GFRTC_ConvertBcdToBinary
-
-	thumb_func_start GFRTC_IsLeapYear
-GFRTC_IsLeapYear: ; 8009148
-	push {r4,lr}
-	lsls r0, 24
-	lsrs r1, r0, 24
-	adds r4, r1, 0
-	movs r0, 0x3
-	ands r0, r1
-	cmp r0, 0
-	bne _08009166
-	adds r0, r1, 0
-	movs r1, 0x64
-	bl __umodsi3
-	lsls r0, 24
-	cmp r0, 0
-	bne _08009174
-_08009166:
-	movs r1, 0xC8
-	lsls r1, 1
-	adds r0, r4, 0
-	bl __modsi3
-	cmp r0, 0
-	bne _08009178
-_08009174:
-	movs r0, 0x1
-	b _0800917A
-_08009178:
-	movs r0, 0
-_0800917A:
-	pop {r4}
-	pop {r1}
-	bx r1
-	thumb_func_end GFRTC_IsLeapYear
-
-	thumb_func_start GFRTC_ConvertYmdToDayCount
-GFRTC_ConvertYmdToDayCount: ; 8009180
-	push {r4-r7,lr}
-	mov r7, r8
-	push {r7}
-	lsls r0, 24
-	lsrs r7, r0, 24
-	lsls r1, 24
-	lsrs r6, r1, 24
-	lsls r2, 24
-	lsrs r2, 24
-	mov r8, r2
-	movs r5, 0
-	subs r4, r7, 0x1
-	cmp r4, 0
-	ble _080091C0
-_0800919C:
-	ldr r1, _08009204
-	adds r0, r5, r1
-	lsls r0, 16
-	lsrs r5, r0, 16
-	lsls r0, r4, 24
-	lsrs r0, 24
-	bl GFRTC_IsLeapYear
-	lsls r0, 24
-	lsrs r0, 24
-	cmp r0, 0x1
-	bne _080091BA
-	adds r0, r5, 0x1
-	lsls r0, 16
-	lsrs r5, r0, 16
-_080091BA:
-	subs r4, 0x1
-	cmp r4, 0
-	bgt _0800919C
-_080091C0:
-	subs r0, r6, 0x1
-	cmp r0, 0
-	ble _080091D8
-	ldr r1, _08009208
-	adds r4, r0, 0
-_080091CA:
-	ldm r1!, {r0}
-	adds r0, r5, r0
-	lsls r0, 16
-	lsrs r5, r0, 16
-	subs r4, 0x1
-	cmp r4, 0
-	bne _080091CA
-_080091D8:
-	cmp r6, 0x2
-	bls _080091F0
-	adds r0, r7, 0
-	bl GFRTC_IsLeapYear
-	lsls r0, 24
-	lsrs r0, 24
-	cmp r0, 0x1
-	bne _080091F0
-	adds r0, r5, 0x1
-	lsls r0, 16
-	lsrs r5, r0, 16
-_080091F0:
-	mov r1, r8
-	adds r0, r5, r1
-	lsls r0, 16
-	lsrs r5, r0, 16
-	adds r0, r5, 0
-	pop {r3}
-	mov r8, r3
-	pop {r4-r7}
-	pop {r1}
-	bx r1
-	.align 2
-_08009204: .4byte 0x0000016d
-_08009208: .4byte gUnknown_081E761C
-	thumb_func_end GFRTC_ConvertYmdToDayCount
-
-	thumb_func_start GFRTC_GetDayCount
-GFRTC_GetDayCount: ; 800920C
-	push {r4-r6,lr}
-	adds r6, r0, 0
-	ldrb r0, [r6]
-	bl GFRTC_ConvertBcdToBinary
-	adds r5, r0, 0
-	lsls r5, 24
-	lsrs r5, 24
-	ldrb r0, [r6, 0x1]
-	bl GFRTC_ConvertBcdToBinary
-	adds r4, r0, 0
-	lsls r4, 24
-	lsrs r4, 24
-	ldrb r0, [r6, 0x2]
-	bl GFRTC_ConvertBcdToBinary
-	adds r2, r0, 0
-	lsls r2, 24
-	lsrs r2, 24
-	adds r0, r5, 0
-	adds r1, r4, 0
-	bl GFRTC_ConvertYmdToDayCount
-	lsls r0, 16
-	lsrs r0, 16
-	pop {r4-r6}
-	pop {r1}
-	bx r1
-	thumb_func_end GFRTC_GetDayCount
-
-	thumb_func_start GameFreakRTC_Init
-GameFreakRTC_Init: ; 8009248
-	push {r4,r5,lr}
-	ldr r5, _08009274
-	movs r0, 0
-	strh r0, [r5]
-	bl GFRTC_DisableInterrupts
-	bl RTC_SetReadWrite
-	bl RTC_Init
-	ldr r4, _08009278
-	strb r0, [r4]
-	bl GFRTC_RestoreInterrupts
-	ldrb r4, [r4]
-	movs r0, 0xF
-	ands r0, r4
-	cmp r0, 0
-	bne _0800927C
-	movs r0, 0x1
-	strh r0, [r5]
-	b _0800929A
-	.align 2
-_08009274: .4byte 0x03000458
-_08009278: .4byte 0x0300046c
-_0800927C:
-	movs r0, 0xF0
-	ands r0, r4
-	cmp r0, 0
-	beq _08009286
-	movs r0, 0x2
-_08009286:
-	strh r0, [r5]
-	ldr r4, _080092A0
-	adds r0, r4, 0
-	bl GFRTC_GetControlRegAndRtcDateTime
-	adds r0, r4, 0
-	bl GFRTC_TestForErrors
-	ldr r1, _080092A4
-	strh r0, [r1]
-_0800929A:
-	pop {r4,r5}
-	pop {r0}
-	bx r0
-	.align 2
-_080092A0: .4byte 0x03000460
-_080092A4: .4byte 0x03000458
-	thumb_func_end GameFreakRTC_Init
-
-	thumb_func_start sub_80092A8
-sub_80092A8: ; 80092A8
-	ldr r0, _080092B0
-	ldrh r0, [r0]
-	bx lr
-	.align 2
-_080092B0: .4byte 0x03000458
-	thumb_func_end sub_80092A8
-
-	thumb_func_start GameFreakRTC_GetRTCDateTime
-GameFreakRTC_GetRTCDateTime: ; 80092B4
-	push {r4,lr}
-	adds r2, r0, 0
-	ldr r0, _080092D0
-	ldrh r1, [r0]
-	movs r0, 0xFF
-	lsls r0, 4
-	ands r0, r1
-	cmp r0, 0
-	beq _080092D8
-	adds r1, r2, 0
-	ldr r0, _080092D4
-	ldm r0!, {r2-r4}
-	stm r1!, {r2-r4}
-	b _080092DE
-	.align 2
-_080092D0: .4byte 0x03000458
-_080092D4: .4byte gUnknown_081E7610
-_080092D8:
-	adds r0, r2, 0
-	bl GFRTC_GetControlRegAndRtcDateTime
-_080092DE:
-	pop {r4}
-	pop {r0}
-	bx r0
-	thumb_func_end GameFreakRTC_GetRTCDateTime
-
-	thumb_func_start GameFreakRTC_GetRTCDateTimeInternal
-GameFreakRTC_GetRTCDateTimeInternal: ; 80092E4
-	push {r4,lr}
-	adds r4, r0, 0
-	bl GFRTC_DisableInterrupts
-	adds r0, r4, 0
-	bl RTC_GetDateTime
-	bl GFRTC_RestoreInterrupts
-	pop {r4}
-	pop {r0}
-	bx r0
-	thumb_func_end GameFreakRTC_GetRTCDateTimeInternal
-
-	thumb_func_start GameFreakRTC_GetControlReg
-GameFreakRTC_GetControlReg: ; 80092FC
-	push {r4,lr}
-	adds r4, r0, 0
-	bl GFRTC_DisableInterrupts
-	adds r0, r4, 0
-	bl RTC_GetControlReg
-	bl GFRTC_RestoreInterrupts
-	pop {r4}
-	pop {r0}
-	bx r0
-	thumb_func_end GameFreakRTC_GetControlReg
-
-	thumb_func_start GFRTC_GetControlRegAndRtcDateTime
-GFRTC_GetControlRegAndRtcDateTime: ; 8009314
-	push {r4,lr}
-	adds r4, r0, 0
-	bl GameFreakRTC_GetControlReg
-	adds r0, r4, 0
-	bl GameFreakRTC_GetRTCDateTimeInternal
-	pop {r4}
-	pop {r0}
-	bx r0
-	thumb_func_end GFRTC_GetControlRegAndRtcDateTime
-
-	thumb_func_start GFRTC_TestForErrors
-GFRTC_TestForErrors: ; 8009328
-	push {r4-r7,lr}
-	mov r7, r8
-	push {r7}
-	adds r7, r0, 0
-	ldrb r1, [r7, 0x7]
-	movs r0, 0x80
-	ands r0, r1
-	lsls r0, 24
-	lsrs r0, 24
-	negs r0, r0
-	asrs r4, r0, 31
-	movs r0, 0x20
-	ands r4, r0
-	movs r0, 0x40
-	ands r0, r1
-	cmp r0, 0
-	bne _0800934E
-	movs r0, 0x10
-	orrs r4, r0
-_0800934E:
-	ldrb r0, [r7]
-	bl GFRTC_ConvertBcdToBinary
-	mov r8, r0
-	cmp r0, 0xFF
-	bne _08009362
-	movs r0, 0x40
-	orrs r4, r0
-	lsls r0, r4, 16
-	lsrs r4, r0, 16
-_08009362:
-	ldrb r0, [r7, 0x1]
-	bl GFRTC_ConvertBcdToBinary
-	adds r6, r0, 0
-	cmp r6, 0xFF
-	beq _08009376
-	cmp r6, 0
-	beq _08009376
-	cmp r6, 0xC
-	ble _0800937E
-_08009376:
-	movs r0, 0x80
-	orrs r4, r0
-	lsls r0, r4, 16
-	lsrs r4, r0, 16
-_0800937E:
-	ldrb r0, [r7, 0x2]
-	bl GFRTC_ConvertBcdToBinary
-	adds r5, r0, 0
-	cmp r5, 0xFF
-	bne _08009396
-	movs r1, 0x80
-	lsls r1, 1
-	adds r0, r1, 0
-	orrs r4, r0
-	lsls r0, r4, 16
-	lsrs r4, r0, 16
-_08009396:
-	cmp r6, 0x2
-	bne _080093B4
-	mov r1, r8
-	lsls r0, r1, 24
-	lsrs r0, 24
-	bl GFRTC_IsLeapYear
-	lsls r0, 24
-	lsrs r0, 24
-	ldr r1, _080093B0
-	ldr r1, [r1, 0x4]
-	adds r0, r1
-	b _080093BE
-	.align 2
-_080093B0: .4byte gUnknown_081E761C
-_080093B4:
-	ldr r0, _08009424
-	subs r1, r6, 0x1
-	lsls r1, 2
-	adds r1, r0
-	ldr r0, [r1]
-_080093BE:
-	cmp r5, r0
-	ble _080093CE
-	movs r1, 0x80
-	lsls r1, 1
-	adds r0, r1, 0
-	orrs r4, r0
-	lsls r0, r4, 16
-	lsrs r4, r0, 16
-_080093CE:
-	ldrb r0, [r7, 0x4]
-	bl GFRTC_ConvertBcdToBinary
-	adds r5, r0, 0
-	cmp r5, 0x18
-	ble _080093E6
-	movs r1, 0x80
-	lsls r1, 2
-	adds r0, r1, 0
-	orrs r4, r0
-	lsls r0, r4, 16
-	lsrs r4, r0, 16
-_080093E6:
-	ldrb r0, [r7, 0x5]
-	bl GFRTC_ConvertBcdToBinary
-	adds r5, r0, 0
-	cmp r5, 0x3C
-	ble _080093FE
-	movs r1, 0x80
-	lsls r1, 3
-	adds r0, r1, 0
-	orrs r4, r0
-	lsls r0, r4, 16
-	lsrs r4, r0, 16
-_080093FE:
-	ldrb r0, [r7, 0x6]
-	bl GFRTC_ConvertBcdToBinary
-	adds r5, r0, 0
-	cmp r5, 0x3C
-	ble _08009416
-	movs r1, 0x80
-	lsls r1, 4
-	adds r0, r1, 0
-	orrs r4, r0
-	lsls r0, r4, 16
-	lsrs r4, r0, 16
-_08009416:
-	adds r0, r4, 0
-	pop {r3}
-	mov r8, r3
-	pop {r4-r7}
-	pop {r1}
-	bx r1
-	.align 2
-_08009424: .4byte gUnknown_081E761C
-	thumb_func_end GFRTC_TestForErrors
-
-	thumb_func_start sub_8009428
-sub_8009428: ; 8009428
-	push {lr}
-	bl GFRTC_DisableInterrupts
-	bl RTC_Reset
-	bl GFRTC_RestoreInterrupts
-	pop {r0}
-	bx r0
-	thumb_func_end sub_8009428
-
-	thumb_func_start GameFreakRTC_FormatDecimalTimeString
-GameFreakRTC_FormatDecimalTimeString: ; 800943C
-	push {r4-r6,lr}
-	adds r5, r2, 0
-	adds r6, r3, 0
-	movs r2, 0x2
-	movs r3, 0x2
-	bl ConvertIntToDecimalStringN
-	movs r4, 0xF0
-	strb r4, [r0]
-	adds r0, 0x1
-	adds r1, r5, 0
-	movs r2, 0x2
-	movs r3, 0x2
-	bl ConvertIntToDecimalStringN
-	strb r4, [r0]
-	adds r0, 0x1
-	adds r1, r6, 0
-	movs r2, 0x2
-	movs r3, 0x2
-	bl ConvertIntToDecimalStringN
-	movs r1, 0xFF
-	strb r1, [r0]
-	pop {r4-r6}
-	pop {r0}
-	bx r0
-	thumb_func_end GameFreakRTC_FormatDecimalTimeString
-
-	thumb_func_start GameFreakRTC_FormatHexTimeString
-GameFreakRTC_FormatHexTimeString: ; 8009474
-	push {r4-r6,lr}
-	adds r5, r2, 0
-	adds r6, r3, 0
-	movs r2, 0x2
-	movs r3, 0x2
-	bl ConvertIntToHexStringN
-	movs r4, 0xF0
-	strb r4, [r0]
-	adds r0, 0x1
-	adds r1, r5, 0
-	movs r2, 0x2
-	movs r3, 0x2
-	bl ConvertIntToHexStringN
-	strb r4, [r0]
-	adds r0, 0x1
-	adds r1, r6, 0
-	movs r2, 0x2
-	movs r3, 0x2
-	bl ConvertIntToHexStringN
-	movs r1, 0xFF
-	strb r1, [r0]
-	pop {r4-r6}
-	pop {r0}
-	bx r0
-	thumb_func_end GameFreakRTC_FormatHexTimeString
-
-	thumb_func_start GameFreakRTC_FormatHexTimeStringFromRTCInfo
-GameFreakRTC_FormatHexTimeStringFromRTCInfo: ; 80094AC
-	push {lr}
-	ldr r3, _080094C0
-	ldrb r1, [r3, 0x4]
-	ldrb r2, [r3, 0x5]
-	ldrb r3, [r3, 0x6]
-	bl GameFreakRTC_FormatHexTimeString
-	pop {r0}
-	bx r0
-	.align 2
-_080094C0: .4byte 0x03000460
-	thumb_func_end GameFreakRTC_FormatHexTimeStringFromRTCInfo
-
-	thumb_func_start GameFreakRTC_FormatDecimalYearMonthDayString
-GameFreakRTC_FormatDecimalYearMonthDayString: ; 80094C4
-	push {r4-r6,lr}
-	adds r5, r2, 0
-	adds r6, r3, 0
-	movs r2, 0x2
-	movs r3, 0x4
-	bl ConvertIntToDecimalStringN
-	movs r4, 0xAE
-	strb r4, [r0]
-	adds r0, 0x1
-	adds r1, r5, 0
-	movs r2, 0x2
-	movs r3, 0x2
-	bl ConvertIntToDecimalStringN
-	strb r4, [r0]
-	adds r0, 0x1
-	adds r1, r6, 0
-	movs r2, 0x2
-	movs r3, 0x2
-	bl ConvertIntToDecimalStringN
-	movs r1, 0xFF
-	strb r1, [r0]
-	pop {r4-r6}
-	pop {r0}
-	bx r0
-	thumb_func_end GameFreakRTC_FormatDecimalYearMonthDayString
-
-	thumb_func_start GameFreakRTC_FormatHexYearMonthDayString
-GameFreakRTC_FormatHexYearMonthDayString: ; 80094FC
-	push {r4-r6,lr}
-	adds r5, r2, 0
-	adds r6, r3, 0
-	movs r2, 0x2
-	movs r3, 0x4
-	bl ConvertIntToHexStringN
-	movs r4, 0xAE
-	strb r4, [r0]
-	adds r0, 0x1
-	adds r1, r5, 0
-	movs r2, 0x2
-	movs r3, 0x2
-	bl ConvertIntToHexStringN
-	strb r4, [r0]
-	adds r0, 0x1
-	adds r1, r6, 0
-	movs r2, 0x2
-	movs r3, 0x2
-	bl ConvertIntToHexStringN
-	movs r1, 0xFF
-	strb r1, [r0]
-	pop {r4-r6}
-	pop {r0}
-	bx r0
-	thumb_func_end GameFreakRTC_FormatHexYearMonthDayString
-
-	thumb_func_start GameFreakRTC_GetRTCDelta
-GameFreakRTC_GetRTCDelta: ; 8009534
-	push {r4-r7,lr}
-	adds r5, r0, 0
-	adds r7, r1, 0
-	adds r6, r2, 0
-	bl GFRTC_GetDayCount
-	adds r4, r0, 0
-	lsls r4, 16
-	lsrs r4, 16
-	ldrb r0, [r5, 0x6]
-	bl GFRTC_ConvertBcdToBinary
-	ldrb r1, [r6, 0x4]
-	subs r0, r1
-	strb r0, [r7, 0x4]
-	ldrb r0, [r5, 0x5]
-	bl GFRTC_ConvertBcdToBinary
-	ldrb r1, [r6, 0x3]
-	subs r0, r1
-	strb r0, [r7, 0x3]
-	ldrb r0, [r5, 0x4]
-	bl GFRTC_ConvertBcdToBinary
-	ldrb r1, [r6, 0x2]
-	subs r0, r1
-	strb r0, [r7, 0x2]
-	ldrh r0, [r6]
-	subs r4, r0
-	strh r4, [r7]
-	ldrb r1, [r7, 0x4]
-	movs r0, 0x4
-	ldrsb r0, [r7, r0]
-	cmp r0, 0
-	bge _08009586
-	adds r0, r1, 0
-	adds r0, 0x3C
-	strb r0, [r7, 0x4]
-	ldrb r0, [r7, 0x3]
-	subs r0, 0x1
-	strb r0, [r7, 0x3]
-_08009586:
-	ldrb r1, [r7, 0x3]
-	movs r0, 0x3
-	ldrsb r0, [r7, r0]
-	cmp r0, 0
-	bge _0800959C
-	adds r0, r1, 0
-	adds r0, 0x3C
-	strb r0, [r7, 0x3]
-	ldrb r0, [r7, 0x2]
-	subs r0, 0x1
-	strb r0, [r7, 0x2]
-_0800959C:
-	ldrb r1, [r7, 0x2]
-	movs r0, 0x2
-	ldrsb r0, [r7, r0]
-	cmp r0, 0
-	bge _080095B2
-	adds r0, r1, 0
-	adds r0, 0x18
-	strb r0, [r7, 0x2]
-	ldrh r0, [r7]
-	subs r0, 0x1
-	strh r0, [r7]
-_080095B2:
-	pop {r4-r7}
-	pop {r0}
-	bx r0
-	thumb_func_end GameFreakRTC_GetRTCDelta
-
-	thumb_func_start GameFreakRTC_CalcLocalDateTime
-GameFreakRTC_CalcLocalDateTime: ; 80095B8
-	push {r4,lr}
-	ldr r4, _080095D4
-	adds r0, r4, 0
-	bl GameFreakRTC_GetRTCDateTime
-	ldr r1, _080095D8
-	ldr r2, _080095DC
-	adds r0, r4, 0
-	bl GameFreakRTC_GetRTCDelta
-	pop {r4}
-	pop {r0}
-	bx r0
-	.align 2
-_080095D4: .4byte 0x03000460
-_080095D8: .4byte 0x03004038
-_080095DC: .4byte 0x02024f3c
-	thumb_func_end GameFreakRTC_CalcLocalDateTime
-
-	thumb_func_start GameFreakRTC_CalcRTCToLocalDelta_DayZero
-GameFreakRTC_CalcRTCToLocalDelta_DayZero: ; 80095E0
-	push {lr}
-	adds r3, r0, 0
-	adds r2, r1, 0
-	movs r0, 0
-	adds r1, r3, 0
-	movs r3, 0
-	bl GameFreakRTC_CalcRTCToLocalDelta
-	pop {r0}
-	bx r0
-	thumb_func_end GameFreakRTC_CalcRTCToLocalDelta_DayZero
-
-	thumb_func_start GameFreakRTC_CalcRTCToLocalDelta
-GameFreakRTC_CalcRTCToLocalDelta: ; 80095F4
-	push {r4,r5,lr}
-	ldr r4, _08009618
-	strh r0, [r4]
-	strb r1, [r4, 0x2]
-	strb r2, [r4, 0x3]
-	strb r3, [r4, 0x4]
-	ldr r5, _0800961C
-	adds r0, r5, 0
-	bl GameFreakRTC_GetRTCDateTime
-	ldr r1, _08009620
-	adds r0, r5, 0
-	adds r2, r4, 0
-	bl GameFreakRTC_GetRTCDelta
-	pop {r4,r5}
-	pop {r0}
-	bx r0
-	.align 2
-_08009618: .4byte 0x03004038
-_0800961C: .4byte 0x03000460
-_08009620: .4byte 0x02024f3c
-	thumb_func_end GameFreakRTC_CalcRTCToLocalDelta
-
-	thumb_func_start GameFreakRTC_GetDelta
-GameFreakRTC_GetDelta: ; 8009624
-	push {r4-r6,lr}
-	adds r4, r0, 0
-	ldrb r3, [r2, 0x4]
-	ldrb r0, [r1, 0x4]
-	subs r5, r3, r0
-	strb r5, [r4, 0x4]
-	ldrb r3, [r2, 0x3]
-	ldrb r0, [r1, 0x3]
-	subs r6, r3, r0
-	strb r6, [r4, 0x3]
-	ldrb r0, [r2, 0x2]
-	ldrb r3, [r1, 0x2]
-	subs r0, r3
-	strb r0, [r4, 0x2]
-	ldrh r0, [r2]
-	ldrh r1, [r1]
-	subs r0, r1
-	strh r0, [r4]
-	lsls r0, r5, 24
-	cmp r0, 0
-	bge _08009658
-	adds r0, r5, 0
-	adds r0, 0x3C
-	strb r0, [r4, 0x4]
-	subs r0, r6, 0x1
-	strb r0, [r4, 0x3]
-_08009658:
-	ldrb r1, [r4, 0x3]
-	movs r0, 0x3
-	ldrsb r0, [r4, r0]
-	cmp r0, 0
-	bge _0800966E
-	adds r0, r1, 0
-	adds r0, 0x3C
-	strb r0, [r4, 0x3]
-	ldrb r0, [r4, 0x2]
-	subs r0, 0x1
-	strb r0, [r4, 0x2]
-_0800966E:
-	ldrb r1, [r4, 0x2]
-	movs r0, 0x2
-	ldrsb r0, [r4, r0]
-	cmp r0, 0
-	bge _08009684
-	adds r0, r1, 0
-	adds r0, 0x18
-	strb r0, [r4, 0x2]
-	ldrh r0, [r4]
-	subs r0, 0x1
-	strh r0, [r4]
-_08009684:
-	pop {r4-r6}
-	pop {r0}
-	bx r0
-	thumb_func_end GameFreakRTC_GetDelta
-
-	thumb_func_start GameFreakRTC_GetNumMinutes
-GameFreakRTC_GetNumMinutes: ; 800968C
-	push {r4,lr}
-	ldr r4, _080096C0
-	adds r0, r4, 0
-	bl GameFreakRTC_GetRTCDateTime
-	adds r0, r4, 0
-	bl GFRTC_GetDayCount
-	lsls r0, 16
-	lsrs r0, 16
-	lsls r1, r0, 1
-	adds r1, r0
-	lsls r0, r1, 4
-	subs r0, r1
-	lsls r0, 5
-	ldrb r2, [r4, 0x4]
-	lsls r1, r2, 4
-	subs r1, r2
-	lsls r1, 2
-	adds r0, r1
-	ldrb r4, [r4, 0x5]
-	adds r0, r4
-	pop {r4}
-	pop {r1}
-	bx r1
-	.align 2
-_080096C0: .4byte 0x03000460
-	thumb_func_end GameFreakRTC_GetNumMinutes
+	.include "genasm/rtc_util.s"
 
 	thumb_func_start sub_80096C4
 sub_80096C4: ; 80096C4
@@ -19647,7 +18851,7 @@ sub_8009A64: ; 8009A64
 	adds r1, 0x4
 	movs r0, 0x7
 	strh r0, [r1]
-	bl sub_80092A8
+	bl RtcGetErrorFlags
 	movs r1, 0xFF
 	lsls r1, 4
 	ands r1, r0
@@ -126160,7 +125364,7 @@ _0803F5D0:
 	adds r0, r3
 	b _0803F61C
 _0803F5DA:
-	bl GameFreakRTC_CalcLocalDateTime
+	bl RtcCalcLocalTime
 	ldr r0, _0803F5F8
 	ldrb r0, [r0, 0x2]
 	subs r0, 0xC
@@ -126179,7 +125383,7 @@ _0803F5F6:
 	.align 2
 _0803F5F8: .4byte 0x03004038
 _0803F5FC:
-	bl GameFreakRTC_CalcLocalDateTime
+	bl RtcCalcLocalTime
 	ldr r0, _0803F624
 	ldrb r0, [r0, 0x2]
 	cmp r0, 0xB
@@ -165175,7 +164379,7 @@ NewGameInitData: ; 8052E6C
 	cmp r0, 0x2
 	bne _08052E7E
 _08052E7A:
-	bl sub_8009428
+	bl RtcReset
 _08052E7E:
 	ldr r1, _08052F40
 	movs r0, 0x1
@@ -208403,7 +207607,7 @@ s2C_unknown: ; 8066300
 	lsls r1, 24
 	lsrs r1, 24
 	adds r0, r4, 0
-	bl GameFreakRTC_CalcRTCToLocalDelta_DayZero
+	bl RtcInitLocalTimeOffset
 	movs r0, 0
 	pop {r4,r5}
 	pop {r1}
@@ -208422,7 +207626,7 @@ s2D_unknown: ; 8066338
 	thumb_func_start s2E_unknown
 s2E_unknown: ; 8066344
 	push {lr}
-	bl GameFreakRTC_CalcLocalDateTime
+	bl RtcCalcLocalTime
 	ldr r2, _0806636C
 	ldr r1, _08066370
 	movs r0, 0x2
@@ -216900,7 +216104,7 @@ sub_806A328: ; 806A328
 	push {lr}
 	ldr r0, _0806A350
 	bl FlagSet
-	bl GameFreakRTC_CalcLocalDateTime
+	bl RtcCalcLocalTime
 	ldr r2, _0806A354
 	adds r2, 0xA0
 	ldr r3, _0806A358
@@ -216928,7 +216132,7 @@ InTrainerHill: ; 806A360
 	lsls r0, 24
 	cmp r0, 0
 	beq _0806A380
-	bl GameFreakRTC_CalcLocalDateTime
+	bl RtcCalcLocalTime
 	ldr r4, _0806A38C
 	adds r0, r4, 0
 	bl sub_806A390
@@ -216998,7 +216202,7 @@ sub_806A3F4: ; 806A3F4
 	mov r0, sp
 	adds r1, r6, 0
 	adds r2, r5, 0
-	bl GameFreakRTC_GetDelta
+	bl CalcTimeDifference
 	mov r0, sp
 	movs r2, 0
 	ldrsh r1, [r0, r2]
@@ -218186,7 +217390,7 @@ _0806AD5C: .4byte 0x0202f388
 _0806AD60: .4byte 0x03005eb8
 _0806AD64: .4byte gUnknown_084118A0
 _0806AD68:
-	bl GameFreakRTC_CalcLocalDateTime
+	bl RtcCalcLocalTime
 	ldr r0, _0806AD7C
 	movs r1, 0x50
 	bl AddTask
@@ -218261,7 +217465,7 @@ _0806AE04: .4byte 0x03004b20
 _0806AE08:
 	ldrb r0, [r5, 0x2]
 	bl remove_task
-	bl sub_8009428
+	bl RtcReset
 	ldr r4, _0806AE4C
 	movs r1, 0
 	ldrsh r0, [r4, r1]
@@ -218271,7 +217475,7 @@ _0806AE08:
 	ldrsb r2, [r4, r2]
 	movs r3, 0x4
 	ldrsb r3, [r4, r3]
-	bl GameFreakRTC_CalcRTCToLocalDelta
+	bl RtcCalcLocalTimeOffset
 	ldr r2, _0806AE50
 	adds r2, 0xA0
 	ldr r0, [r4]
@@ -547951,7 +547155,7 @@ sub_810AD58: ; 810AD58
 	ldrsh r0, [r4, r1]
 	movs r2, 0xE
 	ldrsh r1, [r4, r2]
-	bl GameFreakRTC_CalcRTCToLocalDelta_DayZero
+	bl RtcInitLocalTimeOffset
 	movs r0, 0x1
 	negs r0, r0
 	movs r1, 0
@@ -548310,7 +547514,7 @@ sub_810AFE0: ; 810AFE0
 	adds r4, r0, 0
 	lsls r4, 24
 	lsrs r4, 24
-	bl GameFreakRTC_CalcLocalDateTime
+	bl RtcCalcLocalTime
 	ldr r1, _0810B048
 	lsls r0, r4, 2
 	adds r0, r4
@@ -552842,7 +552046,7 @@ sub_810D378: ; 810D378
 	lsls r0, 24
 	cmp r0, 0
 	beq _0810D3BE
-	bl GameFreakRTC_CalcLocalDateTime
+	bl RtcCalcLocalTime
 	ldr r1, _0810D3AC
 	ldr r0, _0810D3B0
 	ldrb r0, [r0, 0x2]
@@ -568816,7 +568020,7 @@ _0811536C:
 	lsrs r4, r0, 24
 	cmp r4, 0x5
 	bls _08115322
-	bl GameFreakRTC_CalcLocalDateTime
+	bl RtcCalcLocalTime
 	add sp, 0x8
 	pop {r4-r6}
 	pop {r0}
diff --git a/data/data2.s b/data/data2.s
index 88cf02113..9f5b37cd8 100644
--- a/data/data2.s
+++ b/data/data2.s
@@ -363,11 +363,8 @@ gUnknown_081E75CC: ; 81E75CC
 gUnknown_081E75FC: ; 81E75FC
 	.incbin "baserom.gba", 0x001e75fc, 0x14
 
-gUnknown_081E7610: ; 81E7610
-	.incbin "baserom.gba", 0x001e7610, 0xc
-
-gUnknown_081E761C: ; 81E761C
-	.incbin "baserom.gba", 0x001e761c, 0x30
+; 81E7610
+	.include "data/rtc_util.s"
 
 gUnknown_081E764C: ; 81E764C
 	.incbin "baserom.gba", 0x001e764c, 0x40
diff --git a/data/rtc_util.s b/data/rtc_util.s
new file mode 100644
index 000000000..9ee05f47e
--- /dev/null
+++ b/data/rtc_util.s
@@ -0,0 +1,32 @@
+	.align 2
+
+; 2000 Jan 1 00:00:00
+gDefaultRtcInfo: ; 81E7610
+	.byte 0
+	.byte 1
+	.byte 1
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+	.byte 0
+
+	.align 2
+
+gNumDaysInMonths: ; 81E761C
+	.4byte 31
+	.4byte 28
+	.4byte 31
+	.4byte 30
+	.4byte 31
+	.4byte 30
+	.4byte 31
+	.4byte 31
+	.4byte 30
+	.4byte 31
+	.4byte 30
+	.4byte 31
diff --git a/include/gba/gba.h b/include/gba/gba.h
new file mode 100644
index 000000000..5a9dc9b2d
--- /dev/null
+++ b/include/gba/gba.h
@@ -0,0 +1,34 @@
+#ifndef GUARD_GBA_GBA_H
+#define GUARD_GBA_GBA_H
+
+#include <stddef.h>
+
+typedef unsigned char  u8;
+typedef unsigned short u16;
+typedef unsigned int   u32;
+typedef signed char    s8;
+typedef signed short   s16;
+typedef signed int     s32;
+
+typedef volatile u8  vu8;
+typedef volatile u16 vu16;
+typedef volatile u32 vu32;
+typedef volatile s8  vs8;
+typedef volatile s16 vs16;
+typedef volatile s32 vs32;
+
+typedef float  f32;
+typedef double f64;
+
+typedef u8  bool8;
+typedef u16 bool16;
+typedef u32 bool32;
+
+#define TRUE  1
+#define FALSE 0
+
+#include "gba/io_reg.h"
+#include "gba/syscall.h"
+#include "gba/macro.h"
+
+#endif // GUARD_GBA_GBA_H
diff --git a/include/global.h b/include/global.h
index 0c7fef66e..1747446f3 100644
--- a/include/global.h
+++ b/include/global.h
@@ -1,35 +1,7 @@
 #ifndef GUARD_GLOBAL_H
 #define GUARD_GLOBAL_H
 
-#include <stddef.h>
-
-typedef unsigned char  u8;
-typedef unsigned short u16;
-typedef unsigned int   u32;
-typedef signed char    s8;
-typedef signed short   s16;
-typedef signed int     s32;
-
-typedef volatile u8  vu8;
-typedef volatile u16 vu16;
-typedef volatile u32 vu32;
-typedef volatile s8  vs8;
-typedef volatile s16 vs16;
-typedef volatile s32 vs32;
-
-typedef float  f32;
-typedef double f64;
-
-typedef u8  bool8;
-typedef u16 bool16;
-typedef u32 bool32;
-
-#define TRUE  1
-#define FALSE 0
-
-#include "gba/io_reg.h"
-#include "gba/syscall.h"
-#include "gba/macro.h"
+#include "gba/gba.h"
 
 extern u8 gStringVar1[];
 extern u8 gStringVar2[];
@@ -41,6 +13,14 @@ enum
     FEMALE
 };
 
+struct Time
+{
+    s16 days;
+    s8 hours;
+    s8 minutes;
+    s8 seconds;
+};
+
 struct SaveBlock2
 {
     u8 playerName[8];
@@ -51,6 +31,8 @@ struct SaveBlock2
     u8 playTimeMinutes;
     u8 playTimeSeconds;
     u8 playTimeVBlanks;
+    u8 filler[0x85];
+    struct Time localTimeOffset;
 };
 
 extern struct SaveBlock2 gSaveBlock2;
diff --git a/include/rtc.h b/include/rtc.h
new file mode 100644
index 000000000..5ecff238f
--- /dev/null
+++ b/include/rtc.h
@@ -0,0 +1,54 @@
+#ifndef GUARD_RTC_H
+#define GUARD_RTC_H
+
+#include "gba/gba.h"
+
+#define RTC_INFO_CTRL_UNK1          0x01 // unknown
+#define RTC_INFO_CTRL_IRQ_ENABLE    0x02 // per-minute IRQ enable
+#define RTC_INFO_CTRL_UNK2          0x04 // unknown
+#define RTC_INFO_CTRL_24HOUR        0x40 // 0: 12-hour mode, 1: 24-hour mode
+#define RTC_INFO_CTRL_POWER_FAILURE 0x80 // power failure occurred
+
+enum
+{
+    MONTH_JAN = 1,
+    MONTH_FEB,
+    MONTH_MAR,
+    MONTH_APR,
+    MONTH_MAY,
+    MONTH_JUN,
+    MONTH_JUL,
+    MONTH_AUG,
+    MONTH_SEP,
+    MONTH_OCT,
+    MONTH_NOV,
+    MONTH_DEC
+};
+
+struct RtcInfo
+{
+    u8 year;
+    u8 month;
+    u8 day;
+    u8 dayOfWeek;
+    u8 hour;
+    u8 minute;
+    u8 second;
+    u8 control;
+    u8 unknown1;
+    u8 unknown2;
+};
+
+void RTC_Unprotect();
+void RTC_Protect();
+u8 RTC_Probe();
+bool8 RTC_Reset();
+bool8 RTC_GetControl(struct RtcInfo *rtc);
+bool8 RTC_SetControl(struct RtcInfo *rtc);
+bool8 RTC_GetDateTime(struct RtcInfo *rtc);
+bool8 RTC_SetDateTime(struct RtcInfo *rtc);
+bool8 RTC_GetTime(struct RtcInfo *rtc);
+bool8 RTC_SetTime(struct RtcInfo *rtc);
+bool8 RTC_SetUnknownData(struct RtcInfo *rtc);
+
+#endif // GUARD_RTC_H
diff --git a/include/rtc_util.h b/include/rtc_util.h
new file mode 100644
index 000000000..584b675d6
--- /dev/null
+++ b/include/rtc_util.h
@@ -0,0 +1,20 @@
+#ifndef GUARD_RTC_UTIL_H
+#define GUARD_RTC_UTIL_H
+
+#include "global.h"
+
+void RtcInit();
+u16 RtcGetErrorFlags();
+void RtcReset();
+void FormatDecimalTime(u8 *dest, s32 hour, s32 minute, s32 second);
+void FormatHexTime(u8 *dest, s32 hour, s32 minute, s32 second);
+void FormatHexRtcTime(u8 *dest);
+void FormatDecimalDate(u8 *dest, s32 year, s32 month, s32 day);
+void FormatHexDate(u8 *dest, s32 year, s32 month, s32 day);
+void RtcCalcLocalTime();
+void RtcInitLocalTimeOffset(s32 hours, s32 minutes);
+void RtcCalcLocalTimeOffset(s32 days, s32 hours, s32 minutes, s32 seconds);
+void CalcTimeDifference(struct Time *result, struct Time *t1, struct Time *t2);
+u32 RtcGetMinuteCount();
+
+#endif // GUARD_RTC_UTIL_H
diff --git a/include/string_util.h b/include/string_util.h
index d1b90aa34..0dee55828 100644
--- a/include/string_util.h
+++ b/include/string_util.h
@@ -1,6 +1,16 @@
 #ifndef GUARD_STRING_UTIL_H
 #define GUARD_STRING_UTIL_H
 
+#include "global.h"
+
+#define CHAR_SPACE          0x00
+#define CHAR_QUESTION_MARK  0xAC
+#define CHAR_HYPHEN         0xAE
+#define CHAR_COLON          0xF0
+#define EXT_CTRL_CODE_BEGIN 0xFC // extended control code
+#define PLACEHOLDER_BEGIN   0xFD // string placeholder
+#define EOS                 0xFF // end of string
+
 enum StringConvertMode
 {
     STR_CONV_MODE_LEFT_ALIGN,
diff --git a/iwram_syms.txt b/iwram_syms.txt
index cbcd2de7b..5f6e9a8ab 100644
--- a/iwram_syms.txt
+++ b/iwram_syms.txt
@@ -1,5 +1,12 @@
+gRtcErrorFlags = 0x3000458;
+gRtcInfo = 0x3000460;
+gRtcProbeResult = 0x300046C;
+gRtcSavedIme = 0x300046E;
+
 gPlayTimeCounterState = 0x300057C;
 
 gRtcLocked = 0x3000F36;
 
 gUnknownStringVar = 0x3002900;
+
+gLocalTime = 0x3004038;
diff --git a/src/librtc.c b/src/librtc.c
index a64c5af89..b87862a8f 100644
--- a/src/librtc.c
+++ b/src/librtc.c
@@ -1,29 +1,22 @@
-#include "global.h"
-
-struct RtcInfo
-{
-    u8 year;
-    u8 month;
-    u8 dayOfMonth;
-    u8 dayOfWeek;
-    u8 hour;
-    u8 minute;
-    u8 second;
-    u8 control;
-    u8 unknown1;
-    u8 unknown2;
-};
-
-#define OFFSET_YEAR         offsetof(struct RtcInfo, year)
-#define OFFSET_MONTH        offsetof(struct RtcInfo, month)
-#define OFFSET_DAY_OF_MONTH offsetof(struct RtcInfo, dayOfMonth)
-#define OFFSET_DAY_OF_WEEK  offsetof(struct RtcInfo, dayOfWeek)
-#define OFFSET_HOUR         offsetof(struct RtcInfo, hour)
-#define OFFSET_MINUTE       offsetof(struct RtcInfo, minute)
-#define OFFSET_SECOND       offsetof(struct RtcInfo, second)
-#define OFFSET_CONTROL      offsetof(struct RtcInfo, control)
-#define OFFSET_UNKNOWN1     offsetof(struct RtcInfo, unknown1)
-#define OFFSET_UNKNOWN2     offsetof(struct RtcInfo, unknown2)
+#include "gba/gba.h"
+#include "rtc.h"
+
+#define RTC_CTRL_UNK1          0x02 // unknown
+#define RTC_CTRL_IRQ_ENABLE    0x08 // per-minute IRQ enable
+#define RTC_CTRL_UNK2          0x20 // unknown
+#define RTC_CTRL_24HOUR        0x40 // 0: 12-hour mode, 1: 24-hour mode
+#define RTC_CTRL_POWER_FAILURE 0x80 // power failure occurred
+
+#define OFFSET_YEAR        offsetof(struct RtcInfo, year)
+#define OFFSET_MONTH       offsetof(struct RtcInfo, month)
+#define OFFSET_DAY         offsetof(struct RtcInfo, day)
+#define OFFSET_DAY_OF_WEEK offsetof(struct RtcInfo, dayOfWeek)
+#define OFFSET_HOUR        offsetof(struct RtcInfo, hour)
+#define OFFSET_MINUTE      offsetof(struct RtcInfo, minute)
+#define OFFSET_SECOND      offsetof(struct RtcInfo, second)
+#define OFFSET_CONTROL     offsetof(struct RtcInfo, control)
+#define OFFSET_UNKNOWN1    offsetof(struct RtcInfo, unknown1)
+#define OFFSET_UNKNOWN2    offsetof(struct RtcInfo, unknown2)
 
 #define RTC_BUF(info, index) (*((u8 *)(info) + (index)))
 
@@ -33,57 +26,56 @@ struct RtcInfo
 #define RTC_TIME_BUF(info, index) (*((u8 *)(info) + OFFSET_HOUR + (index)))
 #define RTC_TIME_BUF_LEN (OFFSET_SECOND - OFFSET_HOUR + 1)
 
+#define RTC_CMD_RESET       0x60
+#define RTC_CMD_WR_CONTROL  0x62
+#define RTC_CMD_RD_CONTROL  0x63
+#define RTC_CMD_WR_DATETIME 0x64
+#define RTC_CMD_RD_DATETIME 0x65
+#define RTC_CMD_WR_TIME     0x66
+#define RTC_CMD_RD_TIME     0x67
+#define RTC_CMD_WR_UNKNOWN  0x68
+
 extern vu16 GPIOPortData;
 extern vu16 GPIOPortDirection;
-extern vu16 GPIOPortReadWrite;
+extern vu16 GPIOPortReadEnable;
 
 extern bool8 gRtcLocked;
 
-void RTC_SetReadWrite();
-void RTC_SetReadOnly();
-u8 RTC_Init();
-bool8 RTC_Reset();
-bool8 RTC_GetControlReg(struct RtcInfo *rtc);
-bool8 RTC_SetControlReg(struct RtcInfo *rtc);
-bool8 RTC_GetDateTime(struct RtcInfo *rtc);
-bool8 RTC_SetDateTime(struct RtcInfo *rtc);
-bool8 RTC_GetTime(struct RtcInfo *rtc);
-bool8 RTC_SetTime(struct RtcInfo *rtc);
-bool8 RTC_SetUnknownData(struct RtcInfo *rtc);
-s32 RTC_WriteByte(u8 value);
-s32 RTC_WriteByteReversed(u8 value);
-u8 RTC_ReadByte();
-void RTC_SetReadWriteInternal();
-void RTC_SetReadOnlyInternal();
-
-void RTC_SetReadWrite()
+s32 RTC_WriteCommand(u8 value);
+s32 RTC_WriteData(u8 value);
+u8 RTC_ReadData();
+void RTC_EnableGpioPortRead();
+void RTC_DisableGpioPortRead();
+
+void RTC_Unprotect()
 {
-    RTC_SetReadWriteInternal();
+    RTC_EnableGpioPortRead();
     gRtcLocked = FALSE;
 }
 
-void RTC_SetReadOnly()
+void RTC_Protect()
 {
-    RTC_SetReadOnlyInternal();
+    RTC_DisableGpioPortRead();
     gRtcLocked = TRUE;
 }
 
-u8 RTC_Init()
+u8 RTC_Probe()
 {
-    u8 v2;
+    u8 errorCode;
     struct RtcInfo rtc;
 
-    if (!RTC_GetControlReg(&rtc))
+    if (!RTC_GetControl(&rtc))
         return 0;
 
-    v2 = 0;
+    errorCode = 0;
 
-    if ((rtc.control & 0xC0) == 0x80 || !(rtc.control & 0xC0))
+    if ((rtc.control & (RTC_INFO_CTRL_POWER_FAILURE | RTC_INFO_CTRL_24HOUR)) == RTC_INFO_CTRL_POWER_FAILURE
+     || (rtc.control & (RTC_INFO_CTRL_POWER_FAILURE | RTC_INFO_CTRL_24HOUR)) == 0)
     {
         if (!RTC_Reset())
             return 0;
 
-        v2++;
+        errorCode++;
     }
 
     RTC_GetTime(&rtc);
@@ -91,12 +83,12 @@ u8 RTC_Init()
     if (rtc.second & 0x80)
     {
         if (!RTC_Reset())
-            return (v2 << 4) & 0xF0;
+            return (errorCode << 4) & 0xF0;
 
-        v2++;
+        errorCode++;
     }
 
-    return (v2 << 4) | 1;
+    return (errorCode << 4) | 1;
 }
 
 bool8 RTC_Reset()
@@ -114,21 +106,21 @@ bool8 RTC_Reset()
 
     GPIOPortDirection = 7;
 
-    RTC_WriteByte(0x60);
+    RTC_WriteCommand(RTC_CMD_RESET);
 
     GPIOPortData = 1;
     GPIOPortData = 1;
 
     gRtcLocked = FALSE;
 
-    rtc.control = 0x40;
+    rtc.control = RTC_INFO_CTRL_24HOUR;
 
-    result = RTC_SetControlReg(&rtc);
+    result = RTC_SetControl(&rtc);
 
     return result;
 }
 
-bool8 RTC_GetControlReg(struct RtcInfo *rtc)
+bool8 RTC_GetControl(struct RtcInfo *rtc)
 {
     u8 controlData;
 
@@ -142,13 +134,16 @@ bool8 RTC_GetControlReg(struct RtcInfo *rtc)
 
     GPIOPortDirection = 7;
 
-    RTC_WriteByte(0x63);
+    RTC_WriteCommand(RTC_CMD_RD_CONTROL);
 
     GPIOPortDirection = 5;
 
-    controlData = RTC_ReadByte();
+    controlData = RTC_ReadData();
 
-    rtc->control = (controlData & 0xC0) | ((controlData & 0x20) >> 3) | ((controlData & 8) >> 2) | ((controlData & 2) >> 1);
+    rtc->control = (controlData & (RTC_CTRL_POWER_FAILURE | RTC_CTRL_24HOUR))
+                 | ((controlData & RTC_CTRL_UNK2) >> 3)
+                 | ((controlData & RTC_CTRL_IRQ_ENABLE) >> 2)
+                 | ((controlData & RTC_CTRL_UNK1) >> 1);
 
     GPIOPortData = 1;
     GPIOPortData = 1;
@@ -158,7 +153,7 @@ bool8 RTC_GetControlReg(struct RtcInfo *rtc)
     return TRUE;
 }
 
-bool8 RTC_SetControlReg(struct RtcInfo *rtc)
+bool8 RTC_SetControl(struct RtcInfo *rtc)
 {
     u8 controlData;
 
@@ -170,13 +165,16 @@ bool8 RTC_SetControlReg(struct RtcInfo *rtc)
     GPIOPortData = 1;
     GPIOPortData = 5;
 
-    controlData = ((rtc->control & 4) << 3) | (1 << 6) | ((rtc->control & 2) << 2) | ((rtc->control & 1) << 1);
+    controlData = RTC_CTRL_24HOUR
+                | ((rtc->control & RTC_INFO_CTRL_UNK2) << 3)
+                | ((rtc->control & RTC_INFO_CTRL_IRQ_ENABLE) << 2)
+                | ((rtc->control & RTC_INFO_CTRL_UNK1) << 1);
 
     GPIOPortDirection = 7;
 
-    RTC_WriteByte(0x62);
+    RTC_WriteCommand(RTC_CMD_WR_CONTROL);
 
-    RTC_WriteByteReversed(controlData);
+    RTC_WriteData(controlData);
 
     GPIOPortData = 1;
     GPIOPortData = 1;
@@ -200,12 +198,12 @@ bool8 RTC_GetDateTime(struct RtcInfo *rtc)
 
     GPIOPortDirection = 7;
 
-    RTC_WriteByte(0x65);
+    RTC_WriteCommand(RTC_CMD_RD_DATETIME);
 
     GPIOPortDirection = 5;
 
     for (i = 0; i < RTC_DATETIME_BUF_LEN; i++)
-        RTC_DATETIME_BUF(rtc, i) = RTC_ReadByte();
+        RTC_DATETIME_BUF(rtc, i) = RTC_ReadData();
 
     RTC_BUF(rtc, OFFSET_HOUR) &= 0x7F;
 
@@ -231,10 +229,10 @@ bool8 RTC_SetDateTime(struct RtcInfo *rtc)
 
     GPIOPortDirection = 7;
 
-    RTC_WriteByte(0x64);
+    RTC_WriteCommand(RTC_CMD_WR_DATETIME);
 
     for (i = 0; i < RTC_DATETIME_BUF_LEN; i++)
-        RTC_WriteByteReversed(RTC_DATETIME_BUF(rtc, i));
+        RTC_WriteData(RTC_DATETIME_BUF(rtc, i));
 
     GPIOPortData = 1;
     GPIOPortData = 1;
@@ -258,12 +256,12 @@ bool8 RTC_GetTime(struct RtcInfo *rtc)
 
     GPIOPortDirection = 7;
 
-    RTC_WriteByte(0x67);
+    RTC_WriteCommand(RTC_CMD_RD_TIME);
 
     GPIOPortDirection = 5;
 
     for (i = 0; i < RTC_TIME_BUF_LEN; i++)
-        RTC_TIME_BUF(rtc, i) = RTC_ReadByte();
+        RTC_TIME_BUF(rtc, i) = RTC_ReadData();
 
     RTC_BUF(rtc, OFFSET_HOUR) &= 0x7F;
 
@@ -289,10 +287,10 @@ bool8 RTC_SetTime(struct RtcInfo *rtc)
 
     GPIOPortDirection = 7;
 
-    RTC_WriteByte(0x66);
+    RTC_WriteCommand(RTC_CMD_WR_TIME);
 
     for (i = 0; i < RTC_TIME_BUF_LEN; i++)
-        RTC_WriteByteReversed(RTC_TIME_BUF(rtc, i));
+        RTC_WriteData(RTC_TIME_BUF(rtc, i));
 
     GPIOPortData = 1;
     GPIOPortData = 1;
@@ -312,9 +310,13 @@ bool8 RTC_SetUnknownData(struct RtcInfo *rtc)
 
     gRtcLocked = TRUE;
 
+    // unknown1 appears to be a BCD number in the range 0-11,
+    // so it may be an hour in 12-hour format.
+    // Months are normally 1-12.
+
     a[0] = ((rtc->unknown1 & 0xF) + 10 * ((rtc->unknown1 >> 4) & 0xF));
 
-    if (a[0] <= 0xB)
+    if (a[0] < 12)
         a[0] = rtc->unknown1;
     else
         a[0] = rtc->unknown1 | 0x80;
@@ -326,10 +328,10 @@ bool8 RTC_SetUnknownData(struct RtcInfo *rtc)
 
     GPIOPortDirection = 7;
 
-    RTC_WriteByte(0x68);
+    RTC_WriteCommand(RTC_CMD_WR_UNKNOWN);
 
     for (i = 0; i < 2; i++)
-        RTC_WriteByteReversed(a[i]);
+        RTC_WriteData(a[i]);
 
     GPIOPortData = 1;
     GPIOPortData = 1;
@@ -339,7 +341,7 @@ bool8 RTC_SetUnknownData(struct RtcInfo *rtc)
     return TRUE;
 }
 
-s32 RTC_WriteByte(u8 value)
+s32 RTC_WriteCommand(u8 value)
 {
     u8 i;
     u8 temp;
@@ -356,7 +358,7 @@ s32 RTC_WriteByte(u8 value)
     // control reaches end of non-void function
 }
 
-s32 RTC_WriteByteReversed(u8 value)
+s32 RTC_WriteData(u8 value)
 {
     u8 i;
     u8 temp;
@@ -373,7 +375,7 @@ s32 RTC_WriteByteReversed(u8 value)
     // control reaches end of non-void function
 }
 
-u8 RTC_ReadByte()
+u8 RTC_ReadData()
 {
     u8 i;
     u8 temp;
@@ -395,12 +397,12 @@ u8 RTC_ReadByte()
     return value;
 }
 
-void RTC_SetReadWriteInternal()
+void RTC_EnableGpioPortRead()
 {
-    GPIOPortReadWrite = 1;
+    GPIOPortReadEnable = 1;
 }
 
-void RTC_SetReadOnlyInternal()
+void RTC_DisableGpioPortRead()
 {
-    GPIOPortReadWrite = 0;
+    GPIOPortReadEnable = 0;
 }
diff --git a/src/rtc_util.c b/src/rtc_util.c
new file mode 100644
index 000000000..b279ec753
--- /dev/null
+++ b/src/rtc_util.c
@@ -0,0 +1,335 @@
+#include "global.h"
+#include "rtc.h"
+#include "rtc_util.h"
+#include "string_util.h"
+
+extern const struct RtcInfo gDefaultRtcInfo;
+extern const s32 gNumDaysInMonths[];
+
+extern u16 gRtcErrorFlags;
+extern struct RtcInfo gRtcInfo;
+extern u8 gRtcProbeResult;
+extern u16 gRtcSavedIme;
+
+extern struct Time gLocalTime;
+
+void RtcDisableInterrupts();
+void RtcRestoreInterrupts();
+u32 ConvertBcdToBinary(u8 bcd);
+bool8 IsLeapYear(u8 year);
+u16 ConvertDateToDayCount(u8 year, u8 month, u8 day);
+u16 RtcGetDayCount(struct RtcInfo *rtc);
+void RtcGetInfo(struct RtcInfo *rtc);
+void RtcGetDateTime(struct RtcInfo *rtc);
+void RtcGetControl(struct RtcInfo *rtc);
+void RtcGetRawInfo(struct RtcInfo *rtc);
+u16 RtcCheckInfo(struct RtcInfo *rtc);
+void RtcCalcTimeDifference(struct RtcInfo *rtc, struct Time *result, struct Time *t);
+
+void RtcDisableInterrupts()
+{
+    gRtcSavedIme = REG_IME;
+    REG_IME = 0;
+}
+
+void RtcRestoreInterrupts()
+{
+    REG_IME = gRtcSavedIme;
+}
+
+u32 ConvertBcdToBinary(u8 bcd)
+{
+    if (bcd > 0x9F)
+        return 0xFF;
+
+    if ((bcd & 0xF) <= 9)
+        return (10 * ((bcd >> 4) & 0xF)) + (bcd & 0xF);
+    else
+        return 0xFF;
+}
+
+bool8 IsLeapYear(u8 year)
+{
+    if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0))
+        return TRUE;
+
+    return FALSE;
+}
+
+u16 ConvertDateToDayCount(u8 year, u8 month, u8 day)
+{
+    s32 i;
+    u16 dayCount = 0;
+
+    for (i = year - 1; i > 0; i--)
+    {
+        dayCount += 365;
+
+        if (IsLeapYear(i) == TRUE)
+            dayCount++;
+    }
+
+    for (i = 0; i < month - 1; i++)
+        dayCount += gNumDaysInMonths[i];
+
+    if (month > MONTH_FEB && IsLeapYear(year) == TRUE)
+        dayCount++;
+
+    dayCount += day;
+
+    return dayCount;
+}
+
+u16 RtcGetDayCount(struct RtcInfo *rtc)
+{
+    u8 year = ConvertBcdToBinary(rtc->year);
+    u8 month = ConvertBcdToBinary(rtc->month);
+    u8 day = ConvertBcdToBinary(rtc->day);
+    return ConvertDateToDayCount(year, month, day);
+}
+
+void RtcInit()
+{
+    gRtcErrorFlags = 0;
+
+    RtcDisableInterrupts();
+    RTC_Unprotect();
+    gRtcProbeResult = RTC_Probe();
+    RtcRestoreInterrupts();
+
+    if (!(gRtcProbeResult & 0xF))
+    {
+        gRtcErrorFlags = 1;
+        return;
+    }
+
+    if (gRtcProbeResult & 0xF0)
+        gRtcErrorFlags = 2;
+    else
+        gRtcErrorFlags = 0;
+
+    RtcGetRawInfo(&gRtcInfo);
+    gRtcErrorFlags = RtcCheckInfo(&gRtcInfo);
+}
+
+u16 RtcGetErrorFlags()
+{
+    return gRtcErrorFlags;
+}
+
+void RtcGetInfo(struct RtcInfo *rtc)
+{
+    if (gRtcErrorFlags & 0xFF0)
+        *rtc = gDefaultRtcInfo;
+    else
+        RtcGetRawInfo(rtc);
+}
+
+void RtcGetDateTime(struct RtcInfo *rtc)
+{
+    RtcDisableInterrupts();
+    RTC_GetDateTime(rtc);
+    RtcRestoreInterrupts();
+}
+
+void RtcGetControl(struct RtcInfo *rtc)
+{
+    RtcDisableInterrupts();
+    RTC_GetControl(rtc);
+    RtcRestoreInterrupts();
+}
+
+void RtcGetRawInfo(struct RtcInfo *rtc)
+{
+    RtcGetControl(rtc);
+    RtcGetDateTime(rtc);
+}
+
+u16 RtcCheckInfo(struct RtcInfo *rtc)
+{
+    u16 errorFlags = 0;
+    s32 year;
+    s32 month;
+    s32 value;
+
+    if (rtc->control & RTC_INFO_CTRL_POWER_FAILURE)
+        errorFlags |= 0x20;
+
+    if (!(rtc->control & RTC_INFO_CTRL_24HOUR))
+        errorFlags |= 0x10;
+
+    year = ConvertBcdToBinary(rtc->year);
+
+    if (year == 0xFF)
+        errorFlags |= 0x40;
+
+    month = ConvertBcdToBinary(rtc->month);
+
+    if (month == 0xFF || month == 0 || month > 12)
+        errorFlags |= 0x80;
+
+    value = ConvertBcdToBinary(rtc->day);
+
+    if (value == 0xFF)
+        errorFlags |= 0x100;
+
+    if (month == MONTH_FEB)
+    {
+        if (value > IsLeapYear(year) + gNumDaysInMonths[month - 1])
+            errorFlags |= 0x100;
+    }
+    else
+    {
+        if (value > gNumDaysInMonths[month - 1])
+            errorFlags |= 0x100;
+    }
+
+    value = ConvertBcdToBinary(rtc->hour);
+
+    if (value > 24)
+        errorFlags |= 0x200;
+
+    value = ConvertBcdToBinary(rtc->minute);
+
+    if (value > 60)
+        errorFlags |= 0x400;
+
+    value = ConvertBcdToBinary(rtc->second);
+
+    if (value > 60)
+        errorFlags |= 0x800;
+
+    return errorFlags;
+}
+
+void RtcReset()
+{
+    RtcDisableInterrupts();
+    RTC_Reset();
+    RtcRestoreInterrupts();
+}
+
+void FormatDecimalTime(u8 *dest, s32 hour, s32 minute, s32 second)
+{
+    dest = ConvertIntToDecimalStringN(dest, hour, STR_CONV_MODE_LEADING_ZEROS, 2);
+    *dest++ = CHAR_COLON;
+    dest = ConvertIntToDecimalStringN(dest, minute, STR_CONV_MODE_LEADING_ZEROS, 2);
+    *dest++ = CHAR_COLON;
+    dest = ConvertIntToDecimalStringN(dest, second, STR_CONV_MODE_LEADING_ZEROS, 2);
+    *dest = EOS;
+}
+
+void FormatHexTime(u8 *dest, s32 hour, s32 minute, s32 second)
+{
+    dest = ConvertIntToHexStringN(dest, hour, STR_CONV_MODE_LEADING_ZEROS, 2);
+    *dest++ = CHAR_COLON;
+    dest = ConvertIntToHexStringN(dest, minute, STR_CONV_MODE_LEADING_ZEROS, 2);
+    *dest++ = CHAR_COLON;
+    dest = ConvertIntToHexStringN(dest, second, STR_CONV_MODE_LEADING_ZEROS, 2);
+    *dest = EOS;
+}
+
+void FormatHexRtcTime(u8 *dest)
+{
+    FormatHexTime(dest, gRtcInfo.hour, gRtcInfo.minute, gRtcInfo.second);
+}
+
+void FormatDecimalDate(u8 *dest, s32 year, s32 month, s32 day)
+{
+    dest = ConvertIntToDecimalStringN(dest, year, STR_CONV_MODE_LEADING_ZEROS, 4);
+    *dest++ = CHAR_HYPHEN;
+    dest = ConvertIntToDecimalStringN(dest, month, STR_CONV_MODE_LEADING_ZEROS, 2);
+    *dest++ = CHAR_HYPHEN;
+    dest = ConvertIntToDecimalStringN(dest, day, STR_CONV_MODE_LEADING_ZEROS, 2);
+    *dest = EOS;
+}
+
+void FormatHexDate(u8 *dest, s32 year, s32 month, s32 day)
+{
+    dest = ConvertIntToHexStringN(dest, year, STR_CONV_MODE_LEADING_ZEROS, 4);
+    *dest++ = CHAR_HYPHEN;
+    dest = ConvertIntToHexStringN(dest, month, STR_CONV_MODE_LEADING_ZEROS, 2);
+    *dest++ = CHAR_HYPHEN;
+    dest = ConvertIntToHexStringN(dest, day, STR_CONV_MODE_LEADING_ZEROS, 2);
+    *dest = EOS;
+}
+
+void RtcCalcTimeDifference(struct RtcInfo *rtc, struct Time *result, struct Time *t)
+{
+    u16 days = RtcGetDayCount(rtc);
+    result->seconds = ConvertBcdToBinary(rtc->second) - t->seconds;
+    result->minutes = ConvertBcdToBinary(rtc->minute) - t->minutes;
+    result->hours = ConvertBcdToBinary(rtc->hour) - t->hours;
+    result->days = days - t->days;
+
+    if (result->seconds < 0)
+    {
+        result->seconds += 60;
+        --result->minutes;
+    }
+
+    if (result->minutes < 0)
+    {
+        result->minutes += 60;
+        --result->hours;
+    }
+
+    if (result->hours < 0)
+    {
+        result->hours += 24;
+        --result->days;
+    }
+}
+
+void RtcCalcLocalTime()
+{
+    RtcGetInfo(&gRtcInfo);
+    RtcCalcTimeDifference(&gRtcInfo, &gLocalTime, &gSaveBlock2.localTimeOffset);
+}
+
+void RtcInitLocalTimeOffset(s32 hours, s32 minutes)
+{
+    RtcCalcLocalTimeOffset(0, hours, minutes, 0);
+}
+
+void RtcCalcLocalTimeOffset(s32 days, s32 hours, s32 minutes, s32 seconds)
+{
+  gLocalTime.days = days;
+  gLocalTime.hours = hours;
+  gLocalTime.minutes = minutes;
+  gLocalTime.seconds = seconds;
+  RtcGetInfo(&gRtcInfo);
+  RtcCalcTimeDifference(&gRtcInfo, &gSaveBlock2.localTimeOffset, &gLocalTime);
+}
+
+void CalcTimeDifference(struct Time *result, struct Time *t1, struct Time *t2)
+{
+    result->seconds = t2->seconds - t1->seconds;
+    result->minutes = t2->minutes - t1->minutes;
+    result->hours = t2->hours - t1->hours;
+    result->days = t2->days - t1->days;
+
+    if (result->seconds < 0)
+    {
+        result->seconds += 60;
+        --result->minutes;
+    }
+
+    if (result->minutes < 0)
+    {
+        result->minutes += 60;
+        --result->hours;
+    }
+
+    if (result->hours < 0)
+    {
+        result->hours += 24;
+        --result->days;
+    }
+}
+
+u32 RtcGetMinuteCount()
+{
+    RtcGetInfo(&gRtcInfo);
+    return (24 * 60) * RtcGetDayCount(&gRtcInfo) + 60 * gRtcInfo.hour + gRtcInfo.minute;
+}
diff --git a/src/string_util.c b/src/string_util.c
index 221319ae3..a2d2d9cd2 100644
--- a/src/string_util.c
+++ b/src/string_util.c
@@ -1,13 +1,6 @@
 #include "global.h"
 #include "string_util.h"
 
-#define CHAR_SPACE         0x00
-#define CHAR_QUESTION_MARK 0xAC
-
-#define EXT_CTRL_CODE_BEGIN 0xFC // extended control code
-#define PLACEHOLDER_BEGIN   0xFD // string placeholder
-#define EOS                 0xFF // end of string
-
 #define MAX_PLACEHOLDER_ID 0xD
 
 typedef u8 *(*ExpandPlaceholderFunc)();