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Luma3DS-3GX/injector/patches/romfsredir.s

102 lines
2.8 KiB
ArmAsm

.arm.little
.create "build/romfsredir.bin", 0
.macro addr, reg, func
add reg, pc, #func-.-8
.endmacro
.macro load, reg, func
ldr reg, [pc, #func-.-8]
.endmacro
; Patch by delebile
.arm
_start:
; Jumps here before the fsOpenFileDirectly call
_mountArchive:
b mountArchive
.word 0xdead0000 ; Substituted opcode
.word 0xdead0001 ; Branch to hooked function
; Jumps here before every iFileOpen call
_fsRedir:
b fsRedir
.word 0xdead0002 ; Substituted opcode
.word 0xdead0003 ; Branch to hooked function
; Mounts the archive and registers it as 'lf:'
mountArchive:
cmp r3, #3
bne _mountArchive + 4
stmfd sp!, {r0-r4, lr}
sub sp, sp, #4
load r1, archiveId
mov r0, sp
load r4, fsMountArchive
blx r4
mov r3, #0
mov r2, #0
ldr r1, [sp]
addr r0, archiveName
load r4, fsRegisterArchive
blx r4
add sp, sp, #4
ldmfd sp!, {r0-r4, lr}
b _mountArchive + 4
; Check the path passed to iFileOpen.
; If it is trying to access a RomFS file, we try to
; open it from the LayeredFS folder.
; If the file cannot be opened, we just open
; it from its original archive like nothing happened
fsRedir:
stmfd sp!, {r0-r12, lr}
ldrb r12, [r1]
cmp r12, #0x72 ; 'r', should include "rom:", "rom2:" and "rex:"
ldrne r11, [pc, #updateRomFsStart-.-8]
cmpne r12, r11
bne endRedir
sub sp, sp, #0x400
pathRedir:
stmfd sp!, {r0-r3}
add r0, sp, #0x10
addr r3, customPath
pathRedir_1:
ldrb r2, [r3], #1
strh r2, [r0], #2
cmp r2, #0
bne pathRedir_1
sub r0, r0, #2
pathRedir_2:
ldrh r2, [r1], #2
cmp r2, #0x3A ; ':'
bne pathRedir_2
pathRedir_3:
ldrh r2, [r1], #2
strh r2, [r0], #2
cmp r2, #0
bne pathRedir_3
ldmfd sp!, {r0-r3}
mov r1, sp
bl _fsRedir + 4
add sp, sp, #0x400
cmp r0, #0
endRedir:
ldmfd sp!, {r0-r12, lr}
moveq r0, #0
bxeq lr
b _fsRedir + 4
.pool
.align 4
archiveName : .dcb "lf:", 0
fsMountArchive : .word 0xdead0005
fsRegisterArchive : .word 0xdead0006
archiveId : .word 0xdead0007
updateRomFsStart : .word 0xdead0008
customPath : .word 0xdead0004
.close