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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2021-2022 Aidan MacDonald
*
* 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; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "config.h"
#include "mips.h"
#include "bootdata.h"
.text
.extern main
.extern system_early_init
.extern _loadaddress
.global _start
.set push
.set mips32
.set noreorder
.set noat
.section .startup.text,"ax",%progbits
_start:
b _realstart
nop
/* Header entries are 4-byte string labels (not null terminated!) followed
* by 4-byte values. Header should begin in the first 128 bytes and should
* be no more than 256 bytes in length. */
_header:
.ascii "BEGINHDR" /* beginning of header */
.ascii "LOAD"
.word _loadaddress
.ascii "ENDH" /* end of header structure */
#ifndef BOOTLOADER
/* Multiboot support header; this is not part of the above header. */
put_boot_data_here
#endif
_realstart:
/* Save bootloader arguments. */
move s0, a0
move s1, a1
move s2, a2
move s3, a3
/* Copy IRAM from BSS to low memory. */
la a0, _iramcopy
la a1, _iramstart
la a2, _iramend
bal _copy
nop
/* Copy TCSM from BSS */
la a0, _tcsmcopy
la a1, _tcsmstart
la a2, _tcsmend
bal _copy
nop
/* Clear the BSS segment (needed to zero-initialize C static values) */
la a0, _bssbegin
la a1, _bssend
bal _clear
move a2, $0
/* Set stack pointer and clear the stack */
la sp, stackend
la a0, stackbegin
li a2, 0xDEADBEEF
bal _clear
move a1, sp
/* Clear the IRQ stack */
la k0, _irqstackend
la a0, _irqstackbegin
bal _clear
move a1, k0
/* Write back D-cache and invalidate I-cache */
li v0, 0x80000000
ori v1, v0, (0x4000 - 32)
mtc0 zero, C0_TAGLO
mtc0 zero, C0_TAGHI
1:
cache DCIndexWBInv, 0(v0)
cache ICIndexStTag, 0(v0)
bne v0, v1, 1b
addiu v0, v0, 32
/* Invalidate BTB */
mfc0 v0, C0_Config, 7
nop
ori v0, v0, 2
mtc0 v0, C0_Config, 7
nop
/* Jump to C code */
jal system_early_init
nop
/* Restore bootloader arguments, jump to main. */
move a0, s0
move a1, s1
move a2, s2
move a3, s3
j main
move ra, zero /* init backtrace root */
/* copy(void* src, void* dst, void* dst_end) */
_copy:
beq a1, a2, 1f
addiu a1, 4
lw t0, 0(a0)
addiu a0, 4
b _copy
sw t0, -4(a1)
1:
jr ra
nop
/* clear(void* dst, void* dst_end, int value) */
_clear:
beq a0, a1, 1f
addiu a0, 4
b _clear
sw a2, -4(a0)
1:
jr ra
nop
.set pop
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