mirror of
https://github.com/fail0verflow/bootmii.git
synced 2024-11-25 21:14:22 +01:00
145 lines
2.6 KiB
ArmAsm
145 lines
2.6 KiB
ArmAsm
/*
|
|
bootmii - a Free Software replacement for the Nintendo/BroadOn boot2.
|
|
system startup
|
|
|
|
Copyright (C) 2008, 2009 Hector Martin "marcan" <marcan@marcan.st>
|
|
|
|
# This code is licensed to you under the terms of the GNU GPL, version 2;
|
|
# see file COPYING or http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt
|
|
*/
|
|
|
|
.arm
|
|
|
|
.extern _main
|
|
.extern __got_start
|
|
.extern __got_end
|
|
.extern __bss_start
|
|
.extern __bss_end
|
|
.extern __stack_addr
|
|
.globl _start
|
|
.globl debug_output
|
|
|
|
|
|
.section .init
|
|
|
|
_start:
|
|
@ Get real address of _start
|
|
sub r4, pc, #8
|
|
@ Subtract offset to get the address that we were loaded at
|
|
ldr r0, =_start
|
|
sub r4, r4, r0
|
|
@ Output 0x42 to the debug port
|
|
mov r0, #0x42
|
|
bl debug_output
|
|
|
|
@ Set up a stack
|
|
ldr sp, =__stack_addr
|
|
add sp, r4
|
|
|
|
@ perform boot2v3 memory controller poke
|
|
bl memctrl_do_sub_sub_poke
|
|
|
|
@ Output 0x43 to the debug port
|
|
mov r0, #0x43
|
|
bl debug_output
|
|
|
|
@ check for a previous GOT relocation
|
|
ldr r1, [pc, #_is_reloced - . - 8]
|
|
cmp r1, #0
|
|
bne done_got
|
|
|
|
@ relocate the GOT entries
|
|
ldr r1, =__got_start
|
|
add r1, r4
|
|
ldr r2, =__got_end
|
|
add r2, r4
|
|
got_loop:
|
|
@ check for the end
|
|
cmp r1, r2
|
|
beq done_got
|
|
@ read the GOT entry
|
|
ldr r3, [r1]
|
|
@ add our base address
|
|
add r3, r4
|
|
str r3, [r1]
|
|
@ move on
|
|
add r1, r1, #4
|
|
b got_loop
|
|
|
|
done_got:
|
|
|
|
@ note that we have already reloced GOT
|
|
mov r1, #1
|
|
str r1, [pc, #_is_reloced - . - 8]
|
|
|
|
@ clear BSS
|
|
ldr r1, =__bss_start
|
|
add r1, r4
|
|
ldr r2, =__bss_end
|
|
add r2, r4
|
|
mov r3, #0
|
|
bss_loop:
|
|
@ check for the end
|
|
cmp r1, r2
|
|
beq done_bss
|
|
@ clear the word and move on
|
|
str r3, [r1]
|
|
add r1, r1, #4
|
|
b bss_loop
|
|
|
|
done_bss:
|
|
mov r0, #0x44
|
|
bl debug_output
|
|
@ take the plunge
|
|
mov r0, r4
|
|
bl _main
|
|
@ _main returned! Go to whatever address it returned...
|
|
mov r1, r0
|
|
mov r0, r4
|
|
mov pc, r1
|
|
|
|
_is_reloced:
|
|
.long 0
|
|
|
|
memctrl_do_sub_sub_poke:
|
|
stmdb sp!, {lr}
|
|
ldr r0, =0x163 @ reg_address
|
|
mov r1, #0x4C @ address
|
|
bl memctrl_sub_poke
|
|
ldr r0, =0x163 @ read address back (flush?)
|
|
bl memctrl_sub_peek
|
|
ldr r0, =0x162 @ reg_data
|
|
mov r1, #1 @ data
|
|
bl memctrl_sub_poke
|
|
ldmia sp!, {pc}
|
|
|
|
memctrl_sub_poke:
|
|
ldr r2, =0xD8B4000
|
|
strh r0, [r2, #0x74] @ reg_address <= address
|
|
ldrh r0, [r2, #0x74] @ read reg_address back
|
|
strh r1, [r2, #0x76] @ reg_data <= data
|
|
mov pc, lr
|
|
|
|
memctrl_sub_peek:
|
|
ldr r2, =0xD8B4000
|
|
strh r0, [r2, #0x74] @ reg_address <= address
|
|
ldrh r0, [r2, #0x74] @ read reg_address back
|
|
ldrh r0, [r2, #0x76] @ data <= reg_data
|
|
mov pc, lr
|
|
|
|
.pool
|
|
|
|
debug_output:
|
|
@ load address of port
|
|
mov r3, #0xd800000
|
|
@ load old value
|
|
ldr r2, [r3, #0xe0]
|
|
@ clear debug byte
|
|
bic r2, r2, #0xFF0000
|
|
@ insert new value
|
|
and r0, r0, #0xFF
|
|
orr r2, r2, r0, LSL #16
|
|
@ store back
|
|
str r2, [r3, #0xe0]
|
|
mov pc, lr
|