Alesis Vortex Wireless 2 patch to send MIDI messages when pressing the ribbon bank buttons

vortex_patch.py

from asm import *

blob = open("image.bin", "rb").read()

start_addr = 0x08003000

patch_start = start_addr + len(blob)

assert patch_start % 4 == 0

code = """
.syntax unified
.thumb_func
send_event_and_change_ribbon:
    push {r3-r5, lr}
    mov r4, r0
    mov r5, r1
    bl %(change_ribbon_bank)d
    add r4, #102
    strb r4, [sp,#1]
    strb r5, [sp,#2]
    mov r0, #0xb0
    strb r0, [sp]
    movs r1, #3
    mov r0, sp
    bl %(send_midi_event_a)d
    movs r1, #3
    mov r0, sp
    bl %(send_midi_event_b)d
    movs r1, #3
    mov r0, sp
    bl %(send_midi_event_c)d
    pop {r3-r5, pc}
""" % {
    "change_ribbon_bank": 0x08008645,
    "send_midi_event_a": 0x080045Ad,
    "send_midi_event_b": 0x080043F1,
    "send_midi_event_c": 0x080046A1,
}

patch_locs = [
    0x08005862,
    0x0800588E,
    0x080058BA,
]

c = THUMBAsm(code, patch_start)
c.objdump()

blob += c.data

for i in patch_locs:
    p = THUMBAsm("bl %d" % (c.send_event_and_change_ribbon+1), i)
    #p.objdump()
    #print(len(p.data))
    assert p.start == i
    assert len(p.data) == 4
    blob = blob[:p.start - start_addr] + p.data + blob[p.end - start_addr:]

open("patched_image.bin", "wb").write(blob)