xiuos/Ubiquitous/XiZi/arch/arm/cortex-m3/boot.S

115 lines
3.2 KiB
ArmAsm

/**
*************** (C) COPYRIGHT 2017 STMicroelectronics ************************
* @file startup_stm32f103xb.s
* @author MCD Application Team
* @brief STM32F103xB Devices vector table for Atollic toolchain.
* This module performs:
* - Set the initial SP
* - Set the initial PC == Reset_Handler,
* - Set the vector table entries with the exceptions ISR address
* - Configure the clock system
* - Branches to main in the C library (which eventually
* calls main()).
* After Reset the Cortex-M3 processor is in Thread mode,
* priority is Privileged, and the Stack is set to Main.
******************************************************************************
* @attention
*
* <h2><center>&copy; Copyright (c) 2017 STMicroelectronics.
* All rights reserved.</center></h2>
*
* This software component is licensed by ST under BSD 3-Clause license,
* the "License"; You may not use this file except in compliance with the
* License. You may obtain a copy of the License at:
* opensource.org/licenses/BSD-3-Clause
*
******************************************************************************
*/
/**
* @file boot.S
* @brief derived from ST standard peripheral library
* @version 1.1
* @author AIIT XUOS Lab
* @date 2021-11-30
*/
/*************************************************
File name: boot.S
Description: Reset and init function
Others:
History:
1. Date: 2021-11-30
Author: AIIT XUOS Lab
Modification:
1. take startup_stm32f103xb.s for XiZi kernel
*************************************************/
.syntax unified
.cpu cortex-m3
.fpu softvfp
.thumb
/* start address for the initialization values of the .data section.
defined in linker script */
.word _sidata
/* start address for the .data section. defined in linker script */
.word _sdata
/* end address for the .data section. defined in linker script */
.word _edata
/* start address for the .bss section. defined in linker script */
.word _sbss
/* end address for the .bss section. defined in linker script */
.word _ebss
.equ BootRAM, 0xF108F85F
/**
* @brief This is the code that gets called when the processor first
* starts execution following a reset event. Only the absolutely
* necessary set is performed, after which the application
* supplied main() routine is called.
* @param None
* @retval : None
*/
.section .text.Reset_Handler
.weak Reset_Handler
.type Reset_Handler, %function
Reset_Handler:
/* Copy the data segment initializers from flash to SRAM */
movs r1, #0
b LoopCopyDataInit
CopyDataInit:
ldr r3, =_sidata
ldr r3, [r3, r1]
str r3, [r0, r1]
adds r1, r1, #4
LoopCopyDataInit:
ldr r0, =_sdata
ldr r3, =_edata
adds r2, r0, r1
cmp r2, r3
bcc CopyDataInit
ldr r2, =_sbss
b LoopFillZerobss
/* Zero fill the bss segment. */
FillZerobss:
movs r3, #0
str r3, [r2], #4
LoopFillZerobss:
ldr r3, = _ebss
cmp r2, r3
bcc FillZerobss
/* Call the clock system intitialization function.*/
bl SystemInit
/* Call the application's entry point.*/
bl entry
bx lr
.size Reset_Handler, .-Reset_Handler