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Atmosphere/sept/sept-secondary/src/start.s

98 lines
2.4 KiB
ArmAsm

/*
* Copyright (c) 2018-2020 Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
*/
.macro CLEAR_GPR_REG_ITER
mov r\@, #0
.endm
.section .text.start, "ax", %progbits
.arm
.align 5
.global _start
.type _start, %function
_start:
/* Switch to system mode, mask all interrupts, clear all flags */
msr cpsr_cxsf, #0xDF
b begin_relocation_loop
_version:
.word 0x00000000 /* Version. */
.word 0x00000000 /* Reserved. */
begin_relocation_loop:
/* Relocate ourselves if necessary */
ldr r2, =__start__
adr r3, _start
cmp r2, r3
beq _relocation_loop_end
/* If we are relocating, we are not rebooting to ourselves. Note that. */
ldr r0, =0x4003FFFC
mov r1, #0x0
str r1, [r0]
ldr r4, =_relocation_loop_end
mov r4, #0x1000
mov r1, #0x0
_relocation_loop:
ldmia r3!, {r5-r12}
stmia r2!, {r5-r12}
add r1, r1, #0x20
cmp r1, r4
bne _relocation_loop
ldr r12, =_second_relocation_start
bx r12
_second_relocation_start:
ldr r4, =__bss_start__
sub r4, r4, r2
mov r1, #0x0
_second_relocation_loop:
ldmia r3!, {r5-r12}
stmia r2!, {r5-r12}
add r1, r1, #0x20
cmp r1, r4
bne _second_relocation_loop
ldr r12, =_relocation_loop_end
bx r12
_relocation_loop_end:
/* Set the stack pointer */
ldr sp, =__stack_top__
mov fp, #0
bl __program_init
/* Set r0 to r12 to 0 (for debugging) & call main */
.rept 13
CLEAR_GPR_REG_ITER
.endr
ldr lr, =__program_exit
ldr r0, =_version
ldr r0, [r0]
b sept_main
/* No need to include this in normal programs: */
.section .chainloader.text.start, "ax", %progbits
.arm
.align 5
.global relocate_and_chainload
.type relocate_and_chainload, %function
relocate_and_chainload:
ldr sp, =__stack_top__
b relocate_and_chainload_main