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stm32 啟動程式詳解

/**
  *************** (C) COPYRIGHT 2017 STMicroelectronics ************************
  * @file      startup_stm32f103xb.s
  * @author    MCD Application Team
  * @brief     STM32F103xB Devices vector table for Atollic toolchain.
  *            STM32F103xB工具鍊的裝置向量表。
  *            This module performs:
  *            本子產品執行:
  *                - Set the initial SP
  *                - Set the initial PC == Reset_Handler,
  *                - Set the vector table entries with the exceptions ISR address  設定向量表條目,但ISR位址除外
  *                - 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.
  *            重置後,Cortex-M3處理器處于線程模式,優先級為特權,堆棧設定為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:
  * 此軟體元件由ST根據BSD 3條款許可證(“許可證”)進行許可;除非符合許可證的要求,否則您不得使用此檔案。您可以通過以下網址獲得許可證副本:
  *                        opensource.org/licenses/BSD-3-Clause
  *
  ******************************************************************************
  */

  .syntax unified                 表示使用了統一彙編語言文法
  .cpu cortex-m3                  MCU為CM3核心
  .fpu softvfp
  .thumb                          Thumb是ARM體系結構中一種16位的指令集。

.global g_pfnVectors             global使得g_pfnVectors可以被其他目标檔案使用
.global Default_Handler          聲明為全局符号

/* start address for the initialization values of the .data section.
defined in linker script  .data節的初始化值的起始位址。在連結器腳本中定義*/
.word _sidata                   定義word變量 (4位元組   32位機)
/* start address for the .data section. defined in linker script */
.word _sdata                .data開始位址
/* end address for the .data section. defined in linker script */
.word _edata                .data開始位址
/* start address for the .bss section. defined in linker script */
.word _sbss                .bss 開始位址
/* end address for the .bss section. defined in linker script */
.word _ebss                 .bss結束位址

.equ  BootRAM,        0xF1E0F85F          定義宏
/**
 * @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.
 * 這是在重置事件後處理器首次開始執行時調用的代碼。隻執行絕對必要的設定,然後調用應用程式提供的main()例程。
 * @param  None
 * @retval : None
*/

  .section .text.Reset_Handler   /*彙程式設計式中以.開頭的名稱并不是指令的助記符,不會被翻譯成機器指令,而是給彙編器一些特殊訓示,稱為彙編訓示(Assembler Directive)或僞操作(Pseudo-operation),由于它不是真正的指令是以加個“僞”字。.section訓示把代碼劃分成若幹個段(Section),程式被作業系統加載執行時,每個段被加載到不同的位址,作業系統對不同的頁面設定不同的讀、寫、執行權限。.data段儲存程式的資料,是可讀可寫的,相當于C程式的全局變量。本程式中沒有定義資料,是以.data段是空的。

 .section .text
.text段儲存代碼,是隻讀和可執行的,後面那些指令都屬于.text段。*/
  .weak Reset_Handler          聲明其他的同名标号優先于該标号被引用。
  .type Reset_Handler, %function  .type name,@type:将符号name的type屬性設為type。其中type可以是function或object
Reset_Handler:

/* Copy the data segment initializers from flash to SRAM */将資料段初始值設定項從flash複制到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                  //把_sdata裡面的資料給r0
  ldr r3, =_edata
  adds r2, r0, r1
  cmp r2, r3
  bcc CopyDataInit                 無進位
  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 static constructors */
/*    bl __libc_init_array */
/* Call the application's entry point.*/
  bl entry
  bx lr
.size Reset_Handler, .-Reset_Handler

/**
 * @brief  This is the code that gets called when the processor receives an
 *         unexpected interrupt.  This simply enters an infinite loop, preserving
 *         the system state for examination by a debugger.
 * 這是當處理器接收到意外中斷時調用的代碼。這隻是進入一個無限循環,保留系統狀态供調試器檢查。
 * @param  None
 * @retval None       
*/
    .section .text.Default_Handler,"ax",%progbits
Default_Handler:
Infinite_Loop:
  b Infinite_Loop
  .size Default_Handler, .-Default_Handler
/******************************************************************************
*
* The minimal vector table for a Cortex M3.  Note that the proper constructs
* must be placed on this to ensure that it ends up at physical address
* M3的最小向量表。請注意,必須将适當的構造放在這個上,以確定它最終位于實體位址
* 0x0000.0000.
*
*******************************************************************************/
  .section .isr_vector,"a",%progbits
  .type g_pfnVectors, %object
  .size g_pfnVectors, .-g_pfnVectors


g_pfnVectors:

  .word  _estack
  .word  Reset_Handler
  .word  NMI_Handler
  .word  HardFault_Handler
  .word  MemManage_Handler
  .word  BusFault_Handler
  .word  UsageFault_Handler
  .word  0
  .word  0
  .word  0
  .word  0
  .word  SVC_Handler
  .word  DebugMon_Handler
  .word  0
  .word  PendSV_Handler
  .word  SysTick_Handler
  .word  WWDG_IRQHandler
  .word  PVD_IRQHandler
  .word  TAMPER_IRQHandler
  .word  RTC_IRQHandler
  .word  FLASH_IRQHandler
  .word  RCC_IRQHandler
  .word  EXTI0_IRQHandler
  .word  EXTI1_IRQHandler
  .word  EXTI2_IRQHandler
  .word  EXTI3_IRQHandler
  .word  EXTI4_IRQHandler
  .word  DMA1_Channel1_IRQHandler
  .word  DMA1_Channel2_IRQHandler
  .word  DMA1_Channel3_IRQHandler
  .word  DMA1_Channel4_IRQHandler
  .word  DMA1_Channel5_IRQHandler
  .word  DMA1_Channel6_IRQHandler
  .word  DMA1_Channel7_IRQHandler
  .word  ADC1_2_IRQHandler
  .word  USB_HP_CAN1_TX_IRQHandler
  .word  USB_LP_CAN1_RX0_IRQHandler
  .word  CAN1_RX1_IRQHandler
  .word  CAN1_SCE_IRQHandler
  .word  EXTI9_5_IRQHandler
  .word  TIM1_BRK_TIM9_IRQHandler
  .word  TIM1_UP_TIM10_IRQHandler
  .word  TIM1_TRG_COM_TIM11_IRQHandler
  .word  TIM1_CC_IRQHandler
  .word  TIM2_IRQHandler
  .word  TIM3_IRQHandler
  .word  TIM4_IRQHandler
  .word  I2C1_EV_IRQHandler
  .word  I2C1_ER_IRQHandler
  .word  I2C2_EV_IRQHandler
  .word  I2C2_ER_IRQHandler
  .word  SPI1_IRQHandler
  .word  SPI2_IRQHandler
  .word  USART1_IRQHandler
  .word  USART2_IRQHandler
  .word  USART3_IRQHandler
  .word  EXTI15_10_IRQHandler
  .word  RTC_Alarm_IRQHandler
  .word  USBWakeUp_IRQHandler
  .word  TIM8_BRK_TIM12_IRQHandler
  .word  TIM8_UP_TIM13_IRQHandler
  .word  TIM8_TRG_COM_TIM14_IRQHandler
  .word  TIM8_CC_IRQHandler
  .word  ADC3_IRQHandler
  .word  FSMC_IRQHandler
  .word  SDIO_IRQHandler
  .word  TIM5_IRQHandler
  .word  SPI3_IRQHandler
  .word  UART4_IRQHandler
  .word  UART5_IRQHandler
  .word  TIM6_IRQHandler
  .word  TIM7_IRQHandler
  .word  DMA2_Channel1_IRQHandler
  .word  DMA2_Channel2_IRQHandler
  .word  DMA2_Channel3_IRQHandler
  .word  DMA2_Channel4_5_IRQHandler
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  0
  .word  BootRAM       /* @0x1E0. This is for boot in RAM mode for 
                         STM32F10x XL-Density devices. */
/*******************************************************************************
*
* Provide weak aliases for each Exception handler to the Default_Handler. 
* As they are weak aliases, any function with the same name will override 
* this definition.
* 為預設\u處理程式的每個異常處理程式提供弱别名。

由于它們是弱别名,任何同名函數都将重寫此定義。
*******************************************************************************/
    
  .weak  NMI_Handler
  .thumb_set NMI_Handler,Default_Handler
  
  .weak  HardFault_Handler
  .thumb_set HardFault_Handler,Default_Handler
  
  .weak  MemManage_Handler
  .thumb_set MemManage_Handler,Default_Handler
  
  .weak  BusFault_Handler
  .thumb_set BusFault_Handler,Default_Handler

  .weak  UsageFault_Handler
  .thumb_set UsageFault_Handler,Default_Handler

  .weak  SVC_Handler
  .thumb_set SVC_Handler,Default_Handler

  .weak  DebugMon_Handler
  .thumb_set DebugMon_Handler,Default_Handler

  .weak  PendSV_Handler
  .thumb_set PendSV_Handler,Default_Handler

  .weak  SysTick_Handler
  .thumb_set SysTick_Handler,Default_Handler

  .weak  WWDG_IRQHandler
  .thumb_set WWDG_IRQHandler,Default_Handler

  .weak  PVD_IRQHandler
  .thumb_set PVD_IRQHandler,Default_Handler

  .weak  TAMPER_IRQHandler
  .thumb_set TAMPER_IRQHandler,Default_Handler

  .weak  RTC_IRQHandler
  .thumb_set RTC_IRQHandler,Default_Handler

  .weak  FLASH_IRQHandler
  .thumb_set FLASH_IRQHandler,Default_Handler

  .weak  RCC_IRQHandler
  .thumb_set RCC_IRQHandler,Default_Handler

  .weak  EXTI0_IRQHandler
  .thumb_set EXTI0_IRQHandler,Default_Handler

  .weak  EXTI1_IRQHandler
  .thumb_set EXTI1_IRQHandler,Default_Handler

  .weak  EXTI2_IRQHandler
  .thumb_set EXTI2_IRQHandler,Default_Handler

  .weak  EXTI3_IRQHandler
  .thumb_set EXTI3_IRQHandler,Default_Handler

  .weak  EXTI4_IRQHandler
  .thumb_set EXTI4_IRQHandler,Default_Handler

  .weak  DMA1_Channel1_IRQHandler
  .thumb_set DMA1_Channel1_IRQHandler,Default_Handler

  .weak  DMA1_Channel2_IRQHandler
  .thumb_set DMA1_Channel2_IRQHandler,Default_Handler

  .weak  DMA1_Channel3_IRQHandler
  .thumb_set DMA1_Channel3_IRQHandler,Default_Handler

  .weak  DMA1_Channel4_IRQHandler
  .thumb_set DMA1_Channel4_IRQHandler,Default_Handler

  .weak  DMA1_Channel5_IRQHandler
  .thumb_set DMA1_Channel5_IRQHandler,Default_Handler

  .weak  DMA1_Channel6_IRQHandler
  .thumb_set DMA1_Channel6_IRQHandler,Default_Handler

  .weak  DMA1_Channel7_IRQHandler
  .thumb_set DMA1_Channel7_IRQHandler,Default_Handler

  .weak  ADC1_2_IRQHandler
  .thumb_set ADC1_2_IRQHandler,Default_Handler

  .weak  USB_HP_CAN1_TX_IRQHandler
  .thumb_set USB_HP_CAN1_TX_IRQHandler,Default_Handler

  .weak  USB_LP_CAN1_RX0_IRQHandler
  .thumb_set USB_LP_CAN1_RX0_IRQHandler,Default_Handler

  .weak  CAN1_RX1_IRQHandler
  .thumb_set CAN1_RX1_IRQHandler,Default_Handler

  .weak  CAN1_SCE_IRQHandler
  .thumb_set CAN1_SCE_IRQHandler,Default_Handler

  .weak  EXTI9_5_IRQHandler
  .thumb_set EXTI9_5_IRQHandler,Default_Handler

  .weak  TIM1_BRK_TIM9_IRQHandler
  .thumb_set TIM1_BRK_TIM9_IRQHandler,Default_Handler

  .weak  TIM1_UP_TIM10_IRQHandler
  .thumb_set TIM1_UP_TIM10_IRQHandler,Default_Handler

  .weak  TIM1_TRG_COM_TIM11_IRQHandler
  .thumb_set TIM1_TRG_COM_TIM11_IRQHandler,Default_Handler

  .weak  TIM1_CC_IRQHandler
  .thumb_set TIM1_CC_IRQHandler,Default_Handler

  .weak  TIM2_IRQHandler
  .thumb_set TIM2_IRQHandler,Default_Handler

  .weak  TIM3_IRQHandler
  .thumb_set TIM3_IRQHandler,Default_Handler

  .weak  TIM4_IRQHandler
  .thumb_set TIM4_IRQHandler,Default_Handler

  .weak  I2C1_EV_IRQHandler
  .thumb_set I2C1_EV_IRQHandler,Default_Handler

  .weak  I2C1_ER_IRQHandler
  .thumb_set I2C1_ER_IRQHandler,Default_Handler

  .weak  I2C2_EV_IRQHandler
  .thumb_set I2C2_EV_IRQHandler,Default_Handler

  .weak  I2C2_ER_IRQHandler
  .thumb_set I2C2_ER_IRQHandler,Default_Handler

  .weak  SPI1_IRQHandler
  .thumb_set SPI1_IRQHandler,Default_Handler

  .weak  SPI2_IRQHandler
  .thumb_set SPI2_IRQHandler,Default_Handler

  .weak  USART1_IRQHandler
  .thumb_set USART1_IRQHandler,Default_Handler

  .weak  USART2_IRQHandler
  .thumb_set USART2_IRQHandler,Default_Handler

  .weak  USART3_IRQHandler
  .thumb_set USART3_IRQHandler,Default_Handler

  .weak  EXTI15_10_IRQHandler
  .thumb_set EXTI15_10_IRQHandler,Default_Handler

  .weak  RTC_Alarm_IRQHandler
  .thumb_set RTC_Alarm_IRQHandler,Default_Handler

  .weak  USBWakeUp_IRQHandler
  .thumb_set USBWakeUp_IRQHandler,Default_Handler

  .weak  TIM8_BRK_TIM12_IRQHandler
  .thumb_set TIM8_BRK_TIM12_IRQHandler,Default_Handler

  .weak  TIM8_UP_TIM13_IRQHandler
  .thumb_set TIM8_UP_TIM13_IRQHandler,Default_Handler

  .weak  TIM8_TRG_COM_TIM14_IRQHandler
  .thumb_set TIM8_TRG_COM_TIM14_IRQHandler,Default_Handler

  .weak  TIM8_CC_IRQHandler
  .thumb_set TIM8_CC_IRQHandler,Default_Handler

  .weak  ADC3_IRQHandler
  .thumb_set ADC3_IRQHandler,Default_Handler

  .weak  FSMC_IRQHandler
  .thumb_set FSMC_IRQHandler,Default_Handler

  .weak  SDIO_IRQHandler
  .thumb_set SDIO_IRQHandler,Default_Handler

  .weak  TIM5_IRQHandler
  .thumb_set TIM5_IRQHandler,Default_Handler

  .weak  SPI3_IRQHandler
  .thumb_set SPI3_IRQHandler,Default_Handler

  .weak  UART4_IRQHandler
  .thumb_set UART4_IRQHandler,Default_Handler

  .weak  UART5_IRQHandler
  .thumb_set UART5_IRQHandler,Default_Handler

  .weak  TIM6_IRQHandler
  .thumb_set TIM6_IRQHandler,Default_Handler

  .weak  TIM7_IRQHandler
  .thumb_set TIM7_IRQHandler,Default_Handler

  .weak  DMA2_Channel1_IRQHandler
  .thumb_set DMA2_Channel1_IRQHandler,Default_Handler

  .weak  DMA2_Channel2_IRQHandler
  .thumb_set DMA2_Channel2_IRQHandler,Default_Handler

  .weak  DMA2_Channel3_IRQHandler
  .thumb_set DMA2_Channel3_IRQHandler,Default_Handler

  .weak  DMA2_Channel4_5_IRQHandler
  .thumb_set DMA2_Channel4_5_IRQHandler,Default_Handler

/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/