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CTCaer
GitHub Repository: CTCaer/hekate
 Path: blob/master/loader/start.S
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/*

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* Copyright (c) 2018 naehrwert

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*

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* This program is free software; you can redistribute it and/or modify it

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* under the terms and conditions of the GNU General Public License,

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* version 2, as published by the Free Software Foundation.

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*

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* This program is distributed in the hope it will be useful, but WITHOUT

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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

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* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for

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* more details.

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*

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* You should have received a copy of the GNU General Public License

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* along with this program.  If not, see <http://www.gnu.org/licenses/>.

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*/

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.section .text._start

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.arm

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.extern _reloc_ipl

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.type _reloc_ipl, %function

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.extern memset

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.type memset, %function

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.extern loader_main

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.type loader_main, %function

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.globl _start

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.type _start, %function

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_start:

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	ADR R0, _start

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	LDR R1, =__ipl_start

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	CMP R0, R1

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	BEQ _real_start

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	/* If we are not in the right location already, copy a relocator to upper IRAM. */

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	ADR R2, _reloc_ipl

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	LDR R3, =0x4003FF00

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	MOV R4, #(_real_start - _reloc_ipl)

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_copy_loop:

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	LDMIA R2!, {R5}

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	STMIA R3!, {R5}

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	SUBS R4, #4

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	BNE _copy_loop

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	/* Use the relocator to copy ourselves into the right place. */

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	LDR R2, =__ipl_end

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	SUB R2, R2, R1

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	LDR R3, =_real_start

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	LDR R4, =0x4003FF00

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	BX R4

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_reloc_ipl:

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	LDMIA R0!, {R4-R7}

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	STMIA R1!, {R4-R7}

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	SUBS R2, #0x10

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	BNE _reloc_ipl

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	/* Jump to the relocated entry. */

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	BX R3

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_real_start:

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	/* Initially, we place our stack in IRAM but will move it to SDRAM later. */

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	LDR SP, =0x40007000

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	LDR R0, =__ldr_end

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	BL loader_main

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	B .

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	.word 0

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	.word 0

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	.word 0

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	.word 0

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	.word 0

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	.word 0

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