74 lines
1.6 KiB
ArmAsm
74 lines
1.6 KiB
ArmAsm
/*
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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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