Decompile GF funcs responsible for overlays

14 files changed, 718 insertions, 548 deletions

diff --git a/arm9/arm9.lcf b/arm9/arm9.lcf
index c9ddc713..41382881 100644
--- a/arm9/arm9.lcf
+++ b/arm9/arm9.lcf
@@ -110,6 +110,8 @@ SECTIONS {
 		unk_02000E0C.o (.text)
 		string_util.o (.text)
 		unk_020023C0.o (.text)
+		poke_overlay.o (.text)
+		unk_020061E8.o (.text)
 		filesystem.o (.text)
 		unk_02006864.o (.text)
 		script.o (.text)
diff --git a/arm9/asm/unk_020023C0.s b/arm9/asm/unk_020023C0.s
index ef8f06bf..0e8dfbdf 100644
--- a/arm9/asm/unk_020023C0.s
+++ b/arm9/asm/unk_020023C0.s
@@ -7792,551 +7792,3 @@ _02005F36:
 	mov r0, #0x0
 	bx lr
 	.balign 4
-
-	; Code that handles overlays?
-
-	thumb_func_start FreeOverlayAllocation
-FreeOverlayAllocation: ; 0x02005F3C
-	push {r4, lr}
-	add r4, r0, #0x0
-	ldr r0, [r4, #0x4]
-	cmp r0, #0x1
-	beq _02005F4A
-	bl ErrorHandling
-_02005F4A:
-	ldr r1, [r4, #0x0]
-	mov r0, #0x0
-	blx FS_UnloadOverlay
-	cmp r0, #0x1
-	beq _02005F5A
-	bl ErrorHandling
-_02005F5A:
-	mov r0, #0x0
-	str r0, [r4, #0x4]
-	pop {r4, pc}
-
-	thumb_func_start UnloadOverlayByID
-UnloadOverlayByID: ; 0x02005F60
-	push {r4, lr}
-	add r4, r0, #0x0
-	bl GetOverlayLoadDestination
-	bl GetLoadedOverlaysInRegion
-	mov r2, #0x0
-	add r3, r0, #0x0
-_02005F70:
-	ldr r1, [r3, #0x4]
-	cmp r1, #0x1
-	bne _02005F86
-	ldr r1, [r3, #0x0]
-	cmp r4, r1
-	bne _02005F86
-	lsl r1, r2, #0x3
-	add r0, r0, r1
-	bl FreeOverlayAllocation
-	pop {r4, pc}
-_02005F86:
-	add r2, r2, #0x1
-	add r3, #0x8
-	cmp r2, #0x8
-	blt _02005F70
-	pop {r4, pc}
-
-	thumb_func_start GetOverlayLoadDestination
-GetOverlayLoadDestination: ; 0x02005F90
-	push {lr}
-	sub sp, #0x2c
-	add r2, r0, #0x0
-	add r0, sp, #0x0
-	mov r1, #0x0
-	blx FS_LoadOverlayInfo
-	cmp r0, #0x1
-	beq _02005FA6
-	bl ErrorHandling
-_02005FA6:
-	mov r0, #0x2
-	ldr r2, [sp, #0x4]
-	lsl r0, r0, #0x18
-	cmp r2, r0
-	bhi _02005FBC
-	lsr r0, r0, #0x1
-	cmp r2, r0
-	blo _02005FBC
-	add sp, #0x2c
-	mov r0, #0x1
-	pop {pc}
-_02005FBC:
-	mov r0, #0x1
-	ldr r1, _02005FD8 ; =0x027E0000
-	lsl r0, r0, #0xe
-	add r0, r1, r0
-	cmp r2, r0
-	bhi _02005FD2
-	cmp r2, r1
-	blo _02005FD2
-	add sp, #0x2c
-	mov r0, #0x2
-	pop {pc}
-_02005FD2:
-	mov r0, #0x0
-	add sp, #0x2c
-	pop {pc}
-	.balign 4
-_02005FD8: .word 0x027E0000
-
-	thumb_func_start HandleLoadOverlay
-HandleLoadOverlay: ; 0x02005FDC
-	push {r3-r7, lr}
-	add r4, r1, #0x0
-	mov r1, #0x0
-	mvn r1, r1
-	add r5, r0, #0x0
-	str r1, [sp, #0x0]
-	bl CanOverlayBeLoaded
-	cmp r0, #0x0
-	bne _02005FF4
-	mov r0, #0x0
-	pop {r3-r7, pc}
-_02005FF4:
-	add r0, r5, #0x0
-	bl GetOverlayLoadDestination
-	add r7, r0, #0x0
-	bl GetLoadedOverlaysInRegion
-	add r3, r0, #0x0
-	mov r6, #0x0
-	add r1, r3, #0x0
-_02006006:
-	ldr r0, [r1, #0x4]
-	cmp r0, #0x0
-	bne _02006018
-	lsl r1, r6, #0x3
-	add r2, r3, r1
-	mov r0, #0x1
-	str r0, [r2, #0x4]
-	str r5, [r3, r1]
-	b _02006020
-_02006018:
-	add r6, r6, #0x1
-	add r1, #0x8
-	cmp r6, #0x8
-	blt _02006006
-_02006020:
-	cmp r6, #0x8
-	blt _0200602C
-	bl ErrorHandling
-	mov r0, #0x0
-	pop {r3-r7, pc}
-_0200602C:
-	sub r6, r7, #0x1
-	cmp r6, #0x1
-	bhi _0200603C
-	mov r0, #0x0
-	mvn r0, r0
-	blx FS_SetDefaultDMA
-	str r0, [sp, #0x0]
-_0200603C:
-	cmp r4, #0x0
-	beq _0200604A
-	cmp r4, #0x1
-	beq _02006056
-	cmp r4, #0x2
-	beq _02006062
-	b _0200606E
-_0200604A:
-	mov r0, #0x0
-	add r1, r5, #0x0
-	bl LoadOverlayNormal
-	add r4, r0, #0x0
-	b _02006076
-_02006056:
-	mov r0, #0x0
-	add r1, r5, #0x0
-	bl LoadOverlayNoInit
-	add r4, r0, #0x0
-	b _02006076
-_02006062:
-	mov r0, #0x0
-	add r1, r5, #0x0
-	bl LoadOverlayNoInitAsync
-	add r4, r0, #0x0
-	b _02006076
-_0200606E:
-	bl ErrorHandling
-	mov r0, #0x0
-	pop {r3-r7, pc}
-_02006076:
-	cmp r6, #0x1
-	bhi _02006080
-	ldr r0, [sp, #0x0]
-	blx FS_SetDefaultDMA
-_02006080:
-	cmp r4, #0x0
-	bne _0200608C
-	bl ErrorHandling
-	mov r0, #0x0
-	pop {r3-r7, pc}
-_0200608C:
-	mov r0, #0x1
-	pop {r3-r7, pc}
-
-	thumb_func_start CanOverlayBeLoaded
-CanOverlayBeLoaded: ; 0x02006090
-	push {r3-r7, lr}
-	sub sp, #0x10
-	add r1, sp, #0xc
-	add r2, sp, #0x8
-	add r4, r0, #0x0
-	bl GetOverlayRamBounds
-	cmp r0, #0x0
-	bne _020060A8
-	add sp, #0x10
-	mov r0, #0x0
-	pop {r3-r7, pc}
-_020060A8:
-	add r0, r4, #0x0
-	bl GetOverlayLoadDestination
-	bl GetLoadedOverlaysInRegion
-	add r5, r0, #0x0
-	mov r4, #0x0
-	add r6, sp, #0x4
-	add r7, sp, #0x0
-_020060BA:
-	ldr r0, [r5, #0x4]
-	cmp r0, #0x1
-	bne _020060FC
-	ldr r0, [r5, #0x0]
-	add r1, r6, #0x0
-	add r2, r7, #0x0
-	bl GetOverlayRamBounds
-	cmp r0, #0x1
-	bne _020060FC
-	ldr r1, [sp, #0x4]
-	ldr r2, [sp, #0xc]
-	cmp r2, r1
-	blo _020060DC
-	ldr r0, [sp, #0x0]
-	cmp r2, r0
-	blo _020060F2
-_020060DC:
-	ldr r3, [sp, #0x8]
-	cmp r3, r1
-	bls _020060E8
-	ldr r0, [sp, #0x0]
-	cmp r3, r0
-	bls _020060F2
-_020060E8:
-	cmp r2, r1
-	bhi _020060FC
-	ldr r0, [sp, #0x0]
-	cmp r3, r0
-	blo _020060FC
-_020060F2:
-	bl ErrorHandling
-	add sp, #0x10
-	mov r0, #0x0
-	pop {r3-r7, pc}
-_020060FC:
-	add r4, r4, #0x1
-	add r5, #0x8
-	cmp r4, #0x8
-	blt _020060BA
-	mov r0, #0x1
-	add sp, #0x10
-	pop {r3-r7, pc}
-	.balign 4
-
-	thumb_func_start GetLoadedOverlaysInRegion
-GetLoadedOverlaysInRegion: ; 0x0200610C
-	cmp r0, #0x0
-	beq _02006118
-	cmp r0, #0x1
-	beq _0200611C
-	cmp r0, #0x2
-	beq _02006120
-_02006118:
-	ldr r0, _02006124 ; =0x021C45B0
-	bx lr
-_0200611C:
-	ldr r0, _02006128 ; =0x021C45F0
-	bx lr
-_02006120:
-	ldr r0, _0200612C ; =0x021C4630
-	bx lr
-	.balign 4
-_02006124: .word 0x021C45B0
-_02006128: .word 0x021C45F0
-_0200612C: .word 0x021C4630
-
-	thumb_func_start GetOverlayRamBounds
-GetOverlayRamBounds: ; 0x02006130
-	push {r4-r5, lr}
-	sub sp, #0x2c
-	add r3, r0, #0x0
-	add r5, r1, #0x0
-	add r4, r2, #0x0
-	add r0, sp, #0x0
-	mov r1, #0x0
-	add r2, r3, #0x0
-	blx FS_LoadOverlayInfo
-	cmp r0, #0x0
-	bne _02006152
-	bl ErrorHandling
-	add sp, #0x2c
-	mov r0, #0x0
-	pop {r4-r5, pc}
-_02006152:
-	ldr r2, [sp, #0x4]
-	str r2, [r5, #0x0]
-	ldr r1, [sp, #0x8]
-	ldr r0, [sp, #0xc]
-	add r0, r1, r0
-	add r0, r2, r0
-	str r0, [r4, #0x0]
-	mov r0, #0x1
-	add sp, #0x2c
-	pop {r4-r5, pc}
-	.balign 4
-
-	thumb_func_start LoadOverlayNormal
-LoadOverlayNormal: ; 0x02006168
-	ldr r3, _0200616C ; =FS_LoadOverlay
-	bx r3
-	.balign 4
-_0200616C: .word FS_LoadOverlay
-
-	thumb_func_start LoadOverlayNoInit
-LoadOverlayNoInit: ; 0x02006170
-	push {lr}
-	sub sp, #0x2c
-	add r3, r0, #0x0
-	add r2, r1, #0x0
-	add r0, sp, #0x0
-	add r1, r3, #0x0
-	blx FS_LoadOverlayInfo
-	cmp r0, #0x0
-	bne _0200618A
-	add sp, #0x2c
-	mov r0, #0x0
-	pop {pc}
-_0200618A:
-	add r0, sp, #0x0
-	blx FS_LoadOverlayImage
-	cmp r0, #0x0
-	bne _0200619A
-	add sp, #0x2c
-	mov r0, #0x0
-	pop {pc}
-_0200619A:
-	add r0, sp, #0x0
-	blx FS_StartOverlay
-	mov r0, #0x1
-	add sp, #0x2c
-	pop {pc}
-	.balign 4
-
-	thumb_func_start LoadOverlayNoInitAsync
-LoadOverlayNoInitAsync: ; 0x020061A8
-	push {lr}
-	sub sp, #0x74
-	add r3, r0, #0x0
-	add r2, r1, #0x0
-	add r0, sp, #0x0
-	add r1, r3, #0x0
-	blx FS_LoadOverlayInfo
-	cmp r0, #0x0
-	bne _020061C2
-	add sp, #0x74
-	mov r0, #0x0
-	pop {pc}
-_020061C2:
-	add r0, sp, #0x2c
-	blx FS_InitFile
-	add r0, sp, #0x0
-	add r1, sp, #0x2c
-	blx FS_LoadOverlayImageAsync
-	add r0, sp, #0x2c
-	blx FS_WaitAsync
-	add r0, sp, #0x2c
-	blx FS_CloseFile
-	add r0, sp, #0x0
-	blx FS_StartOverlay
-	mov r0, #0x1
-	add sp, #0x74
-	pop {pc}
-
-	thumb_func_start FUN_020061E8
-FUN_020061E8: ; 0x020061E8
-	push {r3-r7, lr}
-	add r5, r1, #0x0
-	add r6, r0, #0x0
-	add r7, r2, #0x0
-	cmp r5, #0x0
-	beq _0200620C
-	add r0, r3, #0x0
-	bl FUN_02016998
-	add r4, r0, #0x0
-	bne _02006202
-	mov r0, #0x0
-	pop {r3-r7, pc}
-_02006202:
-	mov r1, #0x0
-	add r2, r5, #0x0
-	blx Call_FillMemWithValue
-	b _0200620E
-_0200620C:
-	mov r4, #0x0
-_0200620E:
-	add r0, r6, #0x0
-	add r1, r4, #0x0
-	add r2, r7, #0x0
-	bl FUN_0200CA44
-	pop {r3-r7, pc}
-	.balign 4
-
-	thumb_func_start FUN_0200621C
-FUN_0200621C: ; 0x0200621C
-	push {r4, lr}
-	add r4, r0, #0x0
-	bl FUN_0201B6C8
-	cmp r0, #0x0
-	beq _0200622C
-	bl FUN_02016A18
-_0200622C:
-	add r0, r4, #0x0
-	bl FUN_0200CAB4
-	pop {r4, pc}
-
-	thumb_func_start FUN_02006234
-FUN_02006234: ; 0x02006234
-	push {r3-r5, lr}
-	add r5, r0, #0x0
-	add r4, r1, #0x0
-	add r0, r2, #0x0
-	mov r1, #0x28
-	bl FUN_02016998
-	add r3, r0, #0x0
-	add r2, r3, #0x0
-	ldmia r5!, {r0-r1}
-	stmia r2!, {r0-r1}
-	ldmia r5!, {r0-r1}
-	stmia r2!, {r0-r1}
-	mov r0, #0x0
-	str r0, [r3, #0x10]
-	str r0, [r3, #0x14]
-	str r4, [r3, #0x18]
-	str r0, [r3, #0x1c]
-	str r0, [r3, #0x20]
-	str r0, [r3, #0x24]
-	add r0, r3, #0x0
-	pop {r3-r5, pc}
-
-	thumb_func_start FUN_02006260
-FUN_02006260: ; 0x02006260
-	ldr r3, _02006264 ; =FUN_02016A18
-	bx r3
-	.balign 4
-_02006264: .word FUN_02016A18 
-
-	thumb_func_start FUN_02006268
-FUN_02006268: ; 0x02006268
-	push {r4, lr}
-	add r4, r0, #0x0
-	add r0, r2, #0x0
-	bl FUN_02016998
-	str r0, [r4, #0x1c]
-	pop {r4, pc}
-	.balign 4
-
-	thumb_func_start FUN_02006278
-FUN_02006278: ; 0x02006278
-	ldr r0, [r0, #0x1c]
-	bx lr
-
-	thumb_func_start FUN_0200627C
-FUN_0200627C: ; 0x0200627C
-	push {r4, lr}
-	add r4, r0, #0x0
-	ldr r0, [r4, #0x1c]
-	bl FUN_02016A18
-	mov r0, #0x0
-	str r0, [r4, #0x1c]
-	pop {r4, pc}
-
-	thumb_func_start FUN_0200628C
-FUN_0200628C: ; 0x0200628C
-	ldr r0, [r0, #0x18]
-	bx lr
-
-	thumb_func_start FUN_02006290
-FUN_02006290: ; 0x02006290
-	push {r4, lr}
-	add r4, r0, #0x0
-	ldr r1, [r4, #0x10]
-	cmp r1, #0x3
-	bhi _0200630E
-	add r1, r1, r1
-	add r1, pc
-	ldrh r1, [r1, #0x6]
-	lsl r1, r1, #0x10
-	asr r1, r1, #0x10
-	add pc, r1
-_020062A6: ; jump table (using 16-bit offset)
-	.short _020062AE - _020062A6 - 2; case 0
-	.short _020062C2 - _020062A6 - 2; case 1
-	.short _020062DA - _020062A6 - 2; case 2
-	.short _020062F0 - _020062A6 - 2; case 3
-_020062AE:
-	mov r1, #0x0
-	ldr r0, [r4, #0xc]
-	mvn r1, r1
-	cmp r0, r1
-	beq _020062BE
-	mov r1, #0x2
-	bl HandleLoadOverlay
-_020062BE:
-	mov r0, #0x1
-	str r0, [r4, #0x10]
-_020062C2:
-	add r1, r4, #0x0
-	ldr r2, [r4, #0x0]
-	add r0, r4, #0x0
-	add r1, #0x14
-	blx r2
-	cmp r0, #0x1
-	bne _0200630E
-	mov r0, #0x2
-	str r0, [r4, #0x10]
-	mov r0, #0x0
-	str r0, [r4, #0x14]
-	b _0200630E
-_020062DA:
-	add r1, r4, #0x0
-	ldr r2, [r4, #0x4]
-	add r1, #0x14
-	blx r2
-	cmp r0, #0x1
-	bne _0200630E
-	mov r0, #0x3
-	str r0, [r4, #0x10]
-	mov r0, #0x0
-	str r0, [r4, #0x14]
-	b _0200630E
-_020062F0:
-	add r1, r4, #0x0
-	ldr r2, [r4, #0x8]
-	add r1, #0x14
-	blx r2
-	cmp r0, #0x1
-	bne _0200630E
-	mov r1, #0x0
-	ldr r0, [r4, #0xc]
-	mvn r1, r1
-	cmp r0, r1
-	beq _0200630A
-	bl UnloadOverlayByID
-_0200630A:
-	mov r0, #0x1
-	pop {r4, pc}
-_0200630E:
-	mov r0, #0x0
-	pop {r4, pc}
-	.balign 4
diff --git a/arm9/asm/unk_020061E8.s b/arm9/asm/unk_020061E8.s
new file mode 100644
index 00000000..3b8df8d6
--- /dev/null
+++ b/arm9/asm/unk_020061E8.s
@@ -0,0 +1,181 @@
+	.include "asm/macros.inc"
+	.include "global.inc"
+	.section .text
+
+	thumb_func_start FUN_020061E8
+FUN_020061E8: ; 0x020061E8
+	push {r3-r7, lr}
+	add r5, r1, #0x0
+	add r6, r0, #0x0
+	add r7, r2, #0x0
+	cmp r5, #0x0
+	beq _0200620C
+	add r0, r3, #0x0
+	bl FUN_02016998
+	add r4, r0, #0x0
+	bne _02006202
+	mov r0, #0x0
+	pop {r3-r7, pc}
+_02006202:
+	mov r1, #0x0
+	add r2, r5, #0x0
+	blx Call_FillMemWithValue
+	b _0200620E
+_0200620C:
+	mov r4, #0x0
+_0200620E:
+	add r0, r6, #0x0
+	add r1, r4, #0x0
+	add r2, r7, #0x0
+	bl FUN_0200CA44
+	pop {r3-r7, pc}
+	.balign 4
+
+	thumb_func_start FUN_0200621C
+FUN_0200621C: ; 0x0200621C
+	push {r4, lr}
+	add r4, r0, #0x0
+	bl FUN_0201B6C8
+	cmp r0, #0x0
+	beq _0200622C
+	bl FUN_02016A18
+_0200622C:
+	add r0, r4, #0x0
+	bl FUN_0200CAB4
+	pop {r4, pc}
+
+	thumb_func_start FUN_02006234
+FUN_02006234: ; 0x02006234
+	push {r3-r5, lr}
+	add r5, r0, #0x0
+	add r4, r1, #0x0
+	add r0, r2, #0x0
+	mov r1, #0x28
+	bl FUN_02016998
+	add r3, r0, #0x0
+	add r2, r3, #0x0
+	ldmia r5!, {r0-r1}
+	stmia r2!, {r0-r1}
+	ldmia r5!, {r0-r1}
+	stmia r2!, {r0-r1}
+	mov r0, #0x0
+	str r0, [r3, #0x10]
+	str r0, [r3, #0x14]
+	str r4, [r3, #0x18]
+	str r0, [r3, #0x1c]
+	str r0, [r3, #0x20]
+	str r0, [r3, #0x24]
+	add r0, r3, #0x0
+	pop {r3-r5, pc}
+
+	thumb_func_start FUN_02006260
+FUN_02006260: ; 0x02006260
+	ldr r3, _02006264 ; =FUN_02016A18
+	bx r3
+	.balign 4
+_02006264: .word FUN_02016A18
+
+	thumb_func_start FUN_02006268
+FUN_02006268: ; 0x02006268
+	push {r4, lr}
+	add r4, r0, #0x0
+	add r0, r2, #0x0
+	bl FUN_02016998
+	str r0, [r4, #0x1c]
+	pop {r4, pc}
+	.balign 4
+
+	thumb_func_start FUN_02006278
+FUN_02006278: ; 0x02006278
+	ldr r0, [r0, #0x1c]
+	bx lr
+
+	thumb_func_start FUN_0200627C
+FUN_0200627C: ; 0x0200627C
+	push {r4, lr}
+	add r4, r0, #0x0
+	ldr r0, [r4, #0x1c]
+	bl FUN_02016A18
+	mov r0, #0x0
+	str r0, [r4, #0x1c]
+	pop {r4, pc}
+
+	thumb_func_start FUN_0200628C
+FUN_0200628C: ; 0x0200628C
+	ldr r0, [r0, #0x18]
+	bx lr
+
+	thumb_func_start FUN_02006290
+FUN_02006290: ; 0x02006290
+	push {r4, lr}
+	add r4, r0, #0x0
+	ldr r1, [r4, #0x10]
+	cmp r1, #0x3
+	bhi _0200630E
+	add r1, r1, r1
+	add r1, pc
+	ldrh r1, [r1, #0x6]
+	lsl r1, r1, #0x10
+	asr r1, r1, #0x10
+	add pc, r1
+_020062A6: ; jump table (using 16-bit offset)
+	.short _020062AE - _020062A6 - 2; case 0
+	.short _020062C2 - _020062A6 - 2; case 1
+	.short _020062DA - _020062A6 - 2; case 2
+	.short _020062F0 - _020062A6 - 2; case 3
+_020062AE:
+	mov r1, #0x0
+	ldr r0, [r4, #0xc]
+	mvn r1, r1
+	cmp r0, r1
+	beq _020062BE
+	mov r1, #0x2
+	bl HandleLoadOverlay
+_020062BE:
+	mov r0, #0x1
+	str r0, [r4, #0x10]
+_020062C2:
+	add r1, r4, #0x0
+	ldr r2, [r4, #0x0]
+	add r0, r4, #0x0
+	add r1, #0x14
+	blx r2
+	cmp r0, #0x1
+	bne _0200630E
+	mov r0, #0x2
+	str r0, [r4, #0x10]
+	mov r0, #0x0
+	str r0, [r4, #0x14]
+	b _0200630E
+_020062DA:
+	add r1, r4, #0x0
+	ldr r2, [r4, #0x4]
+	add r1, #0x14
+	blx r2
+	cmp r0, #0x1
+	bne _0200630E
+	mov r0, #0x3
+	str r0, [r4, #0x10]
+	mov r0, #0x0
+	str r0, [r4, #0x14]
+	b _0200630E
+_020062F0:
+	add r1, r4, #0x0
+	ldr r2, [r4, #0x8]
+	add r1, #0x14
+	blx r2
+	cmp r0, #0x1
+	bne _0200630E
+	mov r1, #0x0
+	ldr r0, [r4, #0xc]
+	mvn r1, r1
+	cmp r0, r1
+	beq _0200630A
+	bl UnloadOverlayByID
+_0200630A:
+	mov r0, #0x1
+	pop {r4, pc}
+_0200630E:
+	mov r0, #0x0
+	pop {r4, pc}
+	.balign 4
diff --git a/arm9/lib/include/CARD_rom.h b/arm9/lib/include/CARD_rom.h
new file mode 100644
index 00000000..327bc995
--- /dev/null
+++ b/arm9/lib/include/CARD_rom.h
@@ -0,0 +1,11 @@
+#ifndef NITRO_CARD_ROM_H_
+#define NITRO_CARD_ROM_H_
+
+typedef struct
+{
+    u32 offset;
+    u32 length;
+}
+CARDRomRegion;
+
+#endif //NITRO_CARD_ROM_H_
diff --git a/arm9/lib/include/FS_archive.h b/arm9/lib/include/FS_archive.h
new file mode 100644
index 00000000..65bb2ea1
--- /dev/null
+++ b/arm9/lib/include/FS_archive.h
@@ -0,0 +1,90 @@
+#ifndef NITRO_FS_ARCHIVE_H_
+#define NITRO_FS_ARCHIVE_H_
+
+#include "nitro.h"
+
+#include "OS_thread.h"
+
+struct FSFile;
+struct FSArchive;
+
+typedef enum {
+    FS_COMMAND_ASYNC_BEGIN = 0,
+    FS_COMMAND_READFILE = FS_COMMAND_ASYNC_BEGIN,
+    FS_COMMAND_WRITEFILE,
+    FS_COMMAND_ASYNC_END,
+
+    FS_COMMAND_SYNC_BEGIN = FS_COMMAND_ASYNC_END,
+    FS_COMMAND_SEEKDIR = FS_COMMAND_SYNC_BEGIN,
+    FS_COMMAND_READDIR,
+    FS_COMMAND_FINDPATH,
+    FS_COMMAND_GETPATH,
+    FS_COMMAND_OPENFILEFAST,
+    FS_COMMAND_OPENFILEDIRECT,
+    FS_COMMAND_CLOSEFILE,
+    FS_COMMAND_SYNC_END,
+
+    FS_COMMAND_STATUS_BEGIN = FS_COMMAND_SYNC_END,
+    FS_COMMAND_ACTIVATE = FS_COMMAND_STATUS_BEGIN,
+    FS_COMMAND_IDLE,
+    FS_COMMAND_SUSPEND,
+    FS_COMMAND_RESUME,
+    FS_COMMAND_STATUS_END,
+
+    FS_COMMAND_INVALID
+} FSCommandType;
+
+typedef enum {
+    FS_RESULT_SUCCESS = 0,
+    FS_RESULT_FAILURE,
+    FS_RESULT_BUSY,
+    FS_RESULT_CANCELED,
+    FS_RESULT_CANCELLED = FS_RESULT_CANCELED, // SDK alias
+    FS_RESULT_UNSUPPORTED,
+    FS_RESULT_ERROR,
+    FS_RESULT_PROC_ASYNC,
+    FS_RESULT_PROC_DEFAULT,
+    FS_RESULT_PROC_UNKNOWN
+}
+FSResult;
+
+typedef FSResult (*FS_ARCHIVE_READ_FUNC) (struct FSArchive *p, void *dst, u32 pos, u32 size);
+typedef FSResult (*FS_ARCHIVE_WRITE_FUNC) (struct FSArchive *p, const void *src, u32 pos, u32 size);
+typedef FSResult (*FS_ARCHIVE_PROC_FUNC) (struct FSFile *, FSCommandType);
+
+typedef struct
+{
+    struct FSFile * prev;
+    struct FSFile * next;
+}
+FSFileLink;
+
+typedef struct FSArchive
+{
+    union
+    {
+        char ptr[4];
+        u32 pack;
+    } name;
+    struct FSArchive * prev;
+    struct FSArchive * next;
+    OSThreadQueue sync_q;
+    OSThreadQueue stat_q;
+    u32 flag;
+    FSFileLink list;
+    u32 base;
+    u32 fat;
+    u32 fat_size;
+    u32 fnt;
+    u32 fnt_size;
+    u32 fat_bak;
+    u32 fnt_bak;
+    void * load_mem;
+    FS_ARCHIVE_READ_FUNC read_func;
+    FS_ARCHIVE_WRITE_FUNC write_func;
+    FS_ARCHIVE_READ_FUNC table_func;
+    FS_ARCHIVE_PROC_FUNC proc;
+    u32 proc_flag;
+} FSArchive;
+
+#endif //NITRO_FS_ARCHIVE_H_
diff --git a/arm9/lib/include/FS_file.h b/arm9/lib/include/FS_file.h
new file mode 100644
index 00000000..08a698d0
--- /dev/null
+++ b/arm9/lib/include/FS_file.h
@@ -0,0 +1,164 @@
+#ifndef NITRO_FS_FILE_H_
+#define NITRO_FS_FILE_H_
+
+#include "nitro.h"
+
+#include "FS_archive.h"
+
+struct FSFile;
+
+#define FS_DMA_NOT_USE ((u32)~0)
+
+typedef struct FSDirPos
+{
+    struct FSArchive *arc;
+    u16 own_id;
+    u16 index;
+    u32 pos;
+}
+FSDirPos;
+
+typedef struct FSFileID
+{
+    struct FSArchive *arc;
+    u32 file_id;
+}
+FSFileID;
+
+typedef struct
+{
+    union
+    {
+        FSFileID file_id;
+        FSDirPos dir_id;
+    };
+    u32 is_directory;
+    u32 name_len;
+    char name[128];
+}
+FSDirEntry;
+
+
+typedef struct
+{
+    FSDirPos pos;
+}
+FSSeekDirInfo;
+
+
+typedef struct
+{
+    FSDirEntry *p_entry;
+    BOOL skip_string;
+}
+FSReadDirInfo;
+
+
+typedef struct
+{
+    FSDirPos pos;
+    const char *path;
+    BOOL find_directory;
+    union
+    {
+        FSFileID *file;
+        FSDirPos *dir;
+    }
+        result;
+}
+FSFindPathInfo;
+
+
+typedef struct
+{
+    u8 *buf;
+    u32 buf_len;
+    u16 total_len;
+    u16 dir_id;
+}
+FSGetPathInfo;
+
+
+typedef struct
+{
+    FSFileID id;
+}
+FSOpenFileFastInfo;
+
+
+typedef struct
+{
+    u32 top;
+    u32 bottom;
+    u32 index;
+}
+FSOpenFileDirectInfo;
+
+
+typedef struct
+{
+    u32 reserved;
+}
+FSCloseFileInfo;
+
+
+typedef struct
+{
+    void *dst;
+    u32 len_org;
+    u32 len;
+}
+FSReadFileInfo;
+
+
+typedef struct
+{
+    const void *src;
+    u32 len_org;
+    u32 len;
+}
+FSWriteFileInfo;
+
+typedef struct FSFile
+{
+    FSFileLink link;
+    struct FSArchive *arc;
+    u32 stat;
+    FSCommandType command;
+    FSResult error;
+    OSThreadQueue queue[1];
+    u32 filler; // Figure out what this actually is
+    union {
+        struct
+        {
+            u32 own_id;
+            u32 top;
+            u32 bottom;
+            u32 pos;
+        } file;
+        struct
+        {
+            FSDirPos pos;
+            u32 parent;
+        } dir;
+    } prop;
+
+    union {
+        FSReadFileInfo readfile;
+        FSWriteFileInfo writefile;
+
+        FSSeekDirInfo seekdir;
+        FSReadDirInfo readdir;
+        FSFindPathInfo findpath;
+        FSGetPathInfo getpath;
+        FSOpenFileFastInfo openfilefast;
+        FSOpenFileDirectInfo openfiledirect;
+        FSCloseFileInfo closefile;
+    };
+}
+FSFile;
+
+u32 FS_SetDefaultDMA(u32 dma_no); // returns the previous selection
+void FS_InitFile(FSFile * p_file);
+
+#endif //NITRO_FS_FILE_H_
diff --git a/arm9/lib/include/FS_overlay.h b/arm9/lib/include/FS_overlay.h
new file mode 100644
index 00000000..967169aa
--- /dev/null
+++ b/arm9/lib/include/FS_overlay.h
@@ -0,0 +1,42 @@
+#ifndef NITRO_FS_OVERLAY_H_
+#define NITRO_FS_OVERLAY_H_
+
+#include "nitro.h"
+#include "MI_exMemory.h"
+#include "FS_file.h"
+#include "CARD_rom.h"
+
+typedef u32 FSOverlayID;
+
+typedef void (*FSOverlayInitFunc) (void);
+
+typedef struct FSOverlayInfoHeader
+{
+    u32 id;
+    u8 *ram_address;
+    u32 ram_size;
+    u32 bss_size;
+    FSOverlayInitFunc *sinit_init;
+    FSOverlayInitFunc *sinit_init_end;
+    u32 file_id;
+    u32 compressed:24;
+    u32 flag:8;
+} FSOverlayInfoHeader;
+
+typedef struct FSOverlayInfo
+{
+    FSOverlayInfoHeader header;
+    MIProcessor target;
+    CARDRomRegion file_pos;
+} FSOverlayInfo;
+
+BOOL    FS_LoadOverlayInfo(FSOverlayInfo *p_ovi, MIProcessor target, FSOverlayID id);
+BOOL    FS_LoadOverlay(MIProcessor target, FSOverlayID id);
+BOOL    FS_UnloadOverlay(MIProcessor target, FSOverlayID id);
+BOOL    FS_LoadOverlayImage(FSOverlayInfo *p_ovi);
+void    FS_StartOverlay(FSOverlayInfo *p_ovi);
+BOOL    FS_LoadOverlayImageAsync(FSOverlayInfo *p_ovi, FSFile *p_file);
+void    FS_WaitAsync(FSFile *p_file);
+void    FS_CloseFile(FSFile *p_file);
+
+#endif //NITRO_FS_OVERLAY_H_
diff --git a/arm9/lib/include/MI_exMemory.h b/arm9/lib/include/MI_exMemory.h
new file mode 100644
index 00000000..4a8a10a8
--- /dev/null
+++ b/arm9/lib/include/MI_exMemory.h
@@ -0,0 +1,9 @@
+#ifndef NITRO_MI_EXMEMORY_H_
+#define NITRO_MI_EXMEMORY_H_
+
+typedef enum {
+    MI_PROCESSOR_ARM9 = 0,
+    MI_PROCESSOR_ARM7 = 1
+} MIProcessor;
+
+#endif //NITRO_MI_EXMEMORY_H_
diff --git a/arm9/lib/include/OS_system.h b/arm9/lib/include/OS_system.h
index 93903315..794e16d2 100644
--- a/arm9/lib/include/OS_system.h
+++ b/arm9/lib/include/OS_system.h
@@ -5,6 +5,7 @@
 #ifndef POKEDIAMOND_OS_SYSTEM_H
 #define POKEDIAMOND_OS_SYSTEM_H
 
+#include "function_target.h"
 #include "consts.h"
 
 typedef enum {
diff --git a/arm9/lib/include/OS_thread.h b/arm9/lib/include/OS_thread.h
index 4fb70bf7..207dac1b 100644
--- a/arm9/lib/include/OS_thread.h
+++ b/arm9/lib/include/OS_thread.h
@@ -7,6 +7,14 @@
 
 typedef struct _OSThread OSThread;
 
+struct _OSThreadQueue
+{
+    OSThread *head;
+    OSThread *tail;
+};
+
+typedef struct _OSThreadQueue OSThreadQueue;
+
 typedef struct OSThreadInfo {
     u16 isNeedRescheduling;
     u16 irqDepth;
diff --git a/arm9/lib/include/mmap.h b/arm9/lib/include/mmap.h
index d94df843..56ae08c8 100644
--- a/arm9/lib/include/mmap.h
+++ b/arm9/lib/include/mmap.h
@@ -12,8 +12,10 @@ extern u32 SDK_AUTOLOAD_DTCM_START[];
 #define HW_MAIN_MEM_SHARED_SIZE 0x00001000
 #define HW_MAIN_MEM_DEBUGGER_OFFSET     0x00700000
 
+#define HW_ITCM_IMAGE 0x01000000
 #define HW_ITCM                 0x01FF8000
 #define HW_ITCM_SIZE            0x00008000
+#define HW_ITCM_END (HW_ITCM + HW_ITCM_SIZE)
 
 #define HW_WRAM                 0x037F8000
 
diff --git a/arm9/lib/include/mmap_global.h b/arm9/lib/include/mmap_global.h
new file mode 100644
index 00000000..e657e46f
--- /dev/null
+++ b/arm9/lib/include/mmap_global.h
@@ -0,0 +1,4 @@
+#ifndef NITRO_MMAP_GLOBAL_H_
+#define NITRO_MMAP_GLOBAL_H_
+
+#endif //NITRO_MMAP_GLOBAL_H_
diff --git a/arm9/src/poke_overlay.c b/arm9/src/poke_overlay.c
new file mode 100644
index 00000000..105881d8
--- /dev/null
+++ b/arm9/src/poke_overlay.c
@@ -0,0 +1,203 @@
+#include "global.h"
+#include "nitro.h"
+#include "FS_file.h"
+#include "FS_overlay.h"
+
+#define OVERLAY_LOAD_WRAM 0
+#define OVERLAY_LOAD_ITCM 1
+#define OVERLAY_LOAD_DTCM 2
+
+extern void ErrorHandling(void);
+
+struct LoadedOverlay {
+    FSOverlayID id;
+    BOOL active;
+};
+
+extern struct LoadedOverlay gLoadedOverlays[3][8];
+
+struct LoadedOverlay* GetLoadedOverlaysInRegion(int);
+BOOL GetOverlayRamBounds(FSOverlayID, void**, void**);
+BOOL CanOverlayBeLoaded(FSOverlayID);
+int GetOverlayLoadDestination(FSOverlayID);
+BOOL LoadOverlayNormal(MIProcessor, FSOverlayID);
+BOOL LoadOverlayNoInit(MIProcessor, FSOverlayID);
+BOOL LoadOverlayNoInitAsync(MIProcessor, FSOverlayID);
+
+THUMB_FUNC void FreeOverlayAllocation(struct LoadedOverlay * loaded)
+{
+    if (loaded->active != TRUE)
+        ErrorHandling();
+    if (FS_UnloadOverlay(MI_PROCESSOR_ARM9, loaded->id) != TRUE)
+        ErrorHandling();
+    loaded->active = FALSE;
+}
+
+THUMB_FUNC void UnloadOverlayByID(FSOverlayID id)
+{
+    struct LoadedOverlay * loaded = GetLoadedOverlaysInRegion(GetOverlayLoadDestination(id));
+    int i;
+    for (i = 0; i < 8; i++)
+    {
+        if (loaded[i].active == TRUE && loaded[i].id == id)
+        {
+            FreeOverlayAllocation(&loaded[i]);
+            break;
+        }
+    }
+}
+
+THUMB_FUNC int GetOverlayLoadDestination(FSOverlayID id)
+{
+    FSOverlayInfo info;
+    u8 *end;
+    u8 *start;
+    if (FS_LoadOverlayInfo(&info, MI_PROCESSOR_ARM9, id) != TRUE)
+        ErrorHandling();
+    start = (u8 *)HW_ITCM_IMAGE;
+    end = (u8 *)HW_ITCM_END;
+    if (info.header.ram_address <= end && info.header.ram_address >= start)
+        return OVERLAY_LOAD_ITCM;
+    start = (u8 *)SDK_AUTOLOAD_DTCM_START;
+    end = start + HW_DTCM_SIZE;
+    if (info.header.ram_address <= end && info.header.ram_address >= start)
+        return OVERLAY_LOAD_DTCM;
+    return OVERLAY_LOAD_WRAM;
+}
+
+THUMB_FUNC BOOL HandleLoadOverlay(FSOverlayID id, int a1)
+{
+    u32 sp0 = FS_DMA_NOT_USE;
+    struct LoadedOverlay *r3;
+    int r7;
+    int r6;
+    BOOL result;
+
+    if (!CanOverlayBeLoaded(id))
+        return FALSE;
+    r7 = GetOverlayLoadDestination(id);
+    r3 = GetLoadedOverlaysInRegion(r7);
+    for (r6 = 0; r6 < 8; r6++)
+    {
+        if (!r3[r6].active)
+        {
+            struct LoadedOverlay * ovly;
+            ovly = &r3[r6];
+            ovly->active = TRUE;
+            ovly->id = id;
+            break;
+        }
+    }
+    if (r6 >= 8)
+    {
+        ErrorHandling();
+        return FALSE;
+    }
+    if (r7 == OVERLAY_LOAD_ITCM || r7 == OVERLAY_LOAD_DTCM)
+    {
+        sp0 = FS_SetDefaultDMA(FS_DMA_NOT_USE);
+    }
+    switch (a1)
+    {
+    case 0:
+        result = LoadOverlayNormal(MI_PROCESSOR_ARM9, id);
+        break;
+    case 1:
+        result = LoadOverlayNoInit(MI_PROCESSOR_ARM9, id);
+        break;
+    case 2:
+        result = LoadOverlayNoInitAsync(MI_PROCESSOR_ARM9, id);
+        break;
+    default:
+        ErrorHandling();
+        return FALSE;
+    }
+    if (r7 == OVERLAY_LOAD_ITCM || r7 == OVERLAY_LOAD_DTCM)
+    {
+        FS_SetDefaultDMA(sp0);
+    }
+    if (result == 0)
+    {
+        ErrorHandling();
+        return FALSE;
+    }
+    return TRUE;
+}
+
+THUMB_FUNC BOOL CanOverlayBeLoaded(FSOverlayID id)
+{
+    void *start, *end, *start2, *end2;
+    struct LoadedOverlay *r5;
+    int i;
+    if (!GetOverlayRamBounds(id, &start, &end))
+        return FALSE;
+    r5 = GetLoadedOverlaysInRegion(GetOverlayLoadDestination(id));
+    for (i = 0; i < 8; i++)
+    {
+        if (r5[i].active == TRUE && GetOverlayRamBounds(r5[i].id, &start2, &end2) == TRUE)
+        {
+            if ((start >= start2 && start < end2) || (end > start2 && end <= end2) || (start <= start2 && end >= end2))
+            {
+                ErrorHandling();
+                return FALSE;
+            }
+        }
+    }
+    return TRUE;
+}
+
+THUMB_FUNC struct LoadedOverlay* GetLoadedOverlaysInRegion(int a0)
+{
+    switch (a0)
+    {
+    case OVERLAY_LOAD_WRAM:
+    default:
+        return gLoadedOverlays[0];
+    case OVERLAY_LOAD_ITCM:
+        return gLoadedOverlays[1];
+    case OVERLAY_LOAD_DTCM:
+        return gLoadedOverlays[2];
+    }
+}
+
+THUMB_FUNC BOOL GetOverlayRamBounds(FSOverlayID id, void ** start, void ** end)
+{
+    FSOverlayInfo info;
+    if (!FS_LoadOverlayInfo(&info, MI_PROCESSOR_ARM9, id)) {
+        ErrorHandling();
+        return FALSE;
+    }
+    *start = (void *)info.header.ram_address;
+    *end = (char *)*start + (info.header.ram_size + info.header.bss_size);
+    return TRUE;
+}
+
+THUMB_FUNC BOOL LoadOverlayNormal(MIProcessor target, FSOverlayID id)
+{
+    return FS_LoadOverlay(target, id);
+}
+
+THUMB_FUNC BOOL LoadOverlayNoInit(MIProcessor target, FSOverlayID id)
+{
+    FSOverlayInfo info;
+    if (!FS_LoadOverlayInfo(&info, target, id))
+        return FALSE;
+    if (!FS_LoadOverlayImage(&info))
+        return FALSE;
+    FS_StartOverlay(&info);
+    return TRUE;
+}
+
+THUMB_FUNC BOOL LoadOverlayNoInitAsync(MIProcessor target, FSOverlayID id)
+{
+    FSOverlayInfo info;
+    FSFile file;
+    if (!FS_LoadOverlayInfo(&info, target, id))
+        return FALSE;
+    FS_InitFile(&file);
+    FS_LoadOverlayImageAsync(&info, &file);
+    FS_WaitAsync(&file);
+    FS_CloseFile(&file);
+    FS_StartOverlay(&info);
+    return TRUE;
+}
diff --git a/arm9/undefined_syms.txt b/arm9/undefined_syms.txt
index a76e7783..a2f736f8 100644
--- a/arm9/undefined_syms.txt
+++ b/arm9/undefined_syms.txt
@@ -22,6 +22,7 @@ gBacklightTop_2 = 0x02106FA0;
 gUnknown21C48B8 = 0x021C48B8;
 gUnk021C4918 = 0x021C4918;
 gUnk021C8C70 = 0x021C8C70;
+gLoadedOverlays = 0x021C45B0;
 OSi_IrqCallbackInfo = 0x021D341C;
 isInitialized = 0x021D347C;
 OSi_StackForDestructor = 0x021D3480;