# World Map Split
The world map split consists of three routines (along with their hooks).

## World Map Loading Routine
This routine changes the loading of the world map to account for the extra tilesets.
Assemble and put into aligned freespace:

```
.text
.align 2
.thumb
.thumb_func
.global worldtileset

main:
    mov r0, #0x0            @ r0: table offset
    ldr r1, mapheader       @ r1: map header
    ldrb r1, [r1, #0x14]
    cmp r1, #0x8E
    bls loadtileset
    mov r0, #0x4
    ldr r2, maparrays
loop:
    ldrb r3, [r2]
    cmp r3, #0xC5
    beq next
    cmp r3, r1
    beq loadtileset
    add r2, #0x1
    b loop
next:
    add r0, #0x4
    cmp r0, #0x8
    bgt loadtileset
    add r2, #0x1
    b loop
loadtileset:
    ldr r1, table
    ldr r1, [r1, r0]
    mov r4, #0x0            @ restore original code
    str r4, [sp]
    mov r0, #0x0
    mov r2, #0x0
    ldr r3, return
    bx r3

.align 2
    mapheader: .word 0x02036DFC
    maparrays: .word 0x083F1AA4
    table: .word 0x08FFFFFF
    return: .word 0x080C030D
```

You should point the `FF FF FF 08` in the assembled code to a table of 4 pointers (one for each tileset).
Hook: `00 48 00 47 FF FF FF 08` at `080C0304`, where `FF FF FF 08` is the pointer to the routine + 1.

## Town Map Loading Routine
This routine hooks into switching pages of the town map.
Assemble and put into aligned freespace:

```
.text
.align 2
.thumb
.thumb_func
.global townmap

main:
    ldr r3, return
    push {r3}
    ldr r2, key1
    ldr r5, key2
    ldr r0, [r5]
    ldr r4, constant
    add r0, r4
    ldrb r0, [r0]
    push {r0-r2}
    ldr r2, table
    lsl r0, #0x2
    add r0, r2
    ldr r0, [r0]
    ldr r1, vram
    swi 0x12
    pop {r0-r2, pc}

.align 2
    key1: .word 0x020399D4
    key2: .word 0x020399D8
    constant: .word 0x1CCA
    table: .word 0x08FFFFFF
    vram: .word 0x06000000
    return: .word 0x080C1615
```

You should point the `FF FF FF 08` in the assembled code to the same table. Make triple sure all the pointers are correct, because this calls `swi 0x12` directly and will probably kill the GBA if a tileset is missing or not compressed.
Hook: `00 4D 28 47 FF FF FF 08` at `080C1608`, where `FF FF FF 08` is the pointer to the routine + 1.

## Town Map Cancel Routine
This routine swaps in the original tileset when you cancel page switching with the B button.
Assemble and put into aligned freespace:

```
.text
.align 2
.thumb
.thumb_func
.global townmapcancel

main:
    ldr r5, return
    push {r5}
    ldr r0, [r4]
    ldr r2, constant
    add r1, r0, r2
    ldrb r1, [r1]
    push {r0-r2}
    ldr r2, table
    lsl r0, r1, #0x2
    add r0, r2
    ldr r0, [r0]
    ldr r1, vram
    swi 0x12
    pop {r0-r2, pc}
.align 2
    constant: .word 0x1CCB
    table: .word 0x08FFFFFF
    vram: .word 0x06000000
    return: .word 0x080C15BD
```

You should point the `FF FF FF 08` in the assembled code to the same table. Again, this calls `swi 0x12` directly and will probably kill the GBA if a tileset is missing or not compressed.
Hook: `01 4D 28 47 C0 46 FF FF FF 08` at `080C15B2`, where `FF FF FF 08` is the pointer to the routine + 1.