mirror of
https://github.com/fail0verflow/mini.git
synced 2024-12-03 16:44:21 +01:00
114 lines
2.2 KiB
ArmAsm
114 lines
2.2 KiB
ArmAsm
|
/*
|
||
|
|
mini - a Free Software replacement for the Nintendo/BroadOn IOS.
|
||
|
|
|
||
|
|
ELF loader: system startup
|
||
|
|
|
||
|
|
Copyright (C) 2008, 2009 Hector Martin "marcan" <marcan@marcansoft.com>
|
||
|
|
|
||
|
|
This program is free software; you can redistribute it and/or modify
|
||
|
|
it under the terms of the GNU General Public License as published by
|
||
|
|
the Free Software Foundation, version 2.
|
||
|
|
|
||
|
|
This program is distributed in the hope that it will be useful,
|
||
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
|
|
GNU General Public License for more details.
|
||
|
|
|
||
|
|
You should have received a copy of the GNU General Public License
|
||
|
|
along with this program; if not, write to the Free Software
|
||
|
|
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
||
|
|
|
||
|
|
*/
|
||
|
|
.arm
|
||
|
|
|
||
|
|
.extern _main
|
||
|
|
.extern __got_start
|
||
|
|
.extern __got_end
|
||
|
|
.extern __bss_start
|
||
|
|
.extern __bss_end
|
||
|
|
.extern __stack_addr
|
||
|
|
.extern delay
|
||
|
|
.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
|
||
|
|
|
||
|
|
@ Output 0x43 to the debug port
|
||
|
|
mov r0, #0x43
|
||
|
|
bl debug_output
|
||
|
|
|
||
|
|
@ 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:
|
||
|
|
@ 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
|
||
|
|
|
||
|
|
.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
|