Atmosphere/fusee/fusee-primary/src/start.s

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/*
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* Copyright (c) 2018-2019 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/>.
*/
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.macro CLEAR_GPR_REG_ITER
mov r\@, #0
.endm
.section .text.start, "ax", %progbits
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.arm
.align 5
.global _start
.type _start, %function
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_start:
/* Switch to system mode, mask all interrupts, clear all flags */
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msr cpsr_cxsf, #0xDF
/* Relocate ourselves if necessary */
ldr r2, =__start__
adr r3, _start
cmp r2, r3
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bne _relocation_loop_end
ldr r4, =__bss_start__
sub r4, r4, r2 /* size >= 32, obviously, and we've declared 32-byte-alignment */
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_relocation_loop:
ldmia r3!, {r5-r12}
stmia r2!, {r5-r12}
subs r4, #0x20
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bne _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
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/* Set r0 to r12 to 0 (for debugging) & call main */
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.rept 13
CLEAR_GPR_REG_ITER
.endr
ldr r0, =__program_argc
ldr r1, =__program_argv
ldr lr, =__program_exit
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ldr r0, [r0]
ldr r1, [r1]
b 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