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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2023 Alessandro Gatti
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
.section .start
.option norvc /* Do not emit compressed instructions. */
.type start, @function
.global start
start:
.cfi_startproc
.option push
.option norelax
la gp, _global_pointer /* Load global pointer register. */
.option pop
csrw satp, zero /* Disable supervisor mode. */
/* Fill stack with a canary value. */
li t0, 0xBBBBBBBB /* Load canary value. */
la t1, _sstack /* Load stack area start address. */
la t2, _estack /* Load stack area end address. */
1:
sw t0, (t1) /* Write canary. */
addi t1, t1, 4 /* Next word. */
bltu t1, t2, 1b /* Loop until stack is filled. */
la sp, _estack /* Load stack pointer. */
/* Clear BSS area. */
la t1, _sbss /* Load BSS area start address. */
la t2, _ebss /* Load BSS area end address. */
1:
sw zero, (t1) /* Clear word. */
addi t1, t1, 4 /* Next word. */
bltu t1, t2, 1b /* Loop until BSS is cleared. */
/* Set program counter. */
la t0, _entry_point /* Load program counter address. */
csrw mepc, t0 /* Store it into machine exception PC. */
tail _entry_point /* Jump to entry point. */
.cfi_endproc
.end
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