嵌入式：STM32的启动(Startup)文件解析

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        启动文件(Startup File)是嵌入式系统开发中的核心组件之一，它用于初始化系统并为主程序的运行做好准备。在大多数情况下，启动文件是用汇编语言编写的，并且与具体的处理器架构和工具链紧密相关。本文将以startup_stm32f103xe.s文件为例，说明启动文件中做了什么。

1、文件说明

  1. ;******************** (C) COPYRIGHT 2017 STMicroelectronics ********************
  2. ;* File Name          : startup_stm32f103xe.s
  3. ;* Author             : MCD Application Team
  4. ;* Description        : STM32F103xE Devices vector table for MDK-ARM toolchain. 
  5. ;*                      This module performs:
  6. ;*                      - Set the initial SP
  7. ;*                      - Set the initial PC == Reset_Handler
  8. ;*                      - Set the vector table entries with the exceptions ISR address
  9. ;*                      - Configure the clock system
  10. ;*                      - Branches to __main in the C library (which eventually
  11. ;*                        calls main()).
  12. ;*                      After Reset the Cortex-M3 processor is in Thread mode,
  13. ;*                      priority is Privileged, and the Stack is set to Main.
  14. ;******************************************************************************
  15. ;* @attention
  16. ;*
  17. ;* Copyright (c) 2017 STMicroelectronics.
  18. ;* All rights reserved.
  19. ;*
  20. ;* This software component is licensed by ST under BSD 3-Clause license,
  21. ;* the "License"; You may not use this file except in compliance with the
  22. ;* License. You may obtain a copy of the License at:
  23. ;*                        opensource.org/licenses/BSD-3-Clause
  24. ;*
  25. ;******************************************************************************

        根据注释说明，该启动文件用于MDK-ARM工具链，完成以下任务：

  • 设置初始堆栈指针(SP)。
  • 设置初始程序计数器(PC)，指向Reset_Handler。
  • 初始化向量表，指定中断和异常处理函数的入口地址。
  • 配置系统时钟。
  • 跳转到 C 库的__main，最终调用用户定义的main()。

        在复位后，Cortex-M3处理器处于线程模式(Thread Mode)、特权级(Privileged)，使用主堆栈(Main Stack)。

2、栈开辟

  1. ; Amount of memory (in bytes) allocated for Stack
  2. ; Tailor this value to your application needs
  3. ; <h> Stack Configuration
  4. ;   <o> Stack Size (in Bytes) <0x0-0xFFFFFFFF:8>
  5. ; </h>
  6.  
  7. Stack_Size      EQU     0x00000400
  8.  
  9.                 AREA    STACK, NOINIT, READWRITE, ALIGN=3
  10. Stack_Mem       SPACE   Stack_Size
  11. __initial_sp

        首先定义了一个名为Stack_Size的常量1024，它表示栈的大小，根据上方的Configuration提示，栈大小按照8字节对齐。

        随后定义了一块名为STACK的内存区域，该区域不需要初始化，可读可写且起始地址按照2^3=8字节对齐。

        接着定义了一个名为Stack_Mem的内存块，其大小为Stack_Size，即1024。

        最后定义标号__initial_sp，代表栈的顶部（栈是从高地址向低地址生长的），该标号表示的地址也是堆栈寄存器(SP)的初始值。

3、堆开辟

  1. ; <h> Heap Configuration
  2. ;   <o>  Heap Size (in Bytes) <0x0-0xFFFFFFFF:8>
  3. ; </h>
  4.  
  5. Heap_Size       EQU     0x00000200
  6.  
  7.                 AREA    HEAP, NOINIT, READWRITE, ALIGN=3
  8. __heap_base
  9. Heap_Mem        SPACE   Heap_Size
  10. __heap_limit

        首先定义了一个名为Heap_Size的常量512，它表示堆的大小，根据上方的Configuration提示，堆大小按照8字节对齐。 

        随后定义了一块名为HEAP的内存区域，该区域不需要初始化，可读可写且起始地址按照2^3=8字节对齐。

        接着定义标号__heap_base，表示堆的起始地址。

        然后定义了一个名为Heap_Mem的内存块，其大小为Heap_Size，即512。

        最后定义标号__heap_limit，表示堆的结束地址。

4、指针对齐和指令集说明

  1.                 PRESERVE8
  2.                 THUMB

        PRESERVE8设置了PRES8构建属性，表示栈指针(SP)保持8字节对齐。THUMB表示接下来的指令是THUMB指令。

5、向量表定义

  1. ; Vector Table Mapped to Address 0 at Reset
  2.                 AREA    RESET, DATA, READONLY
  3.                 EXPORT  __Vectors
  4.                 EXPORT  __Vectors_End
  5.                 EXPORT  __Vectors_Size
  6.  
  7. __Vectors       DCD     __initial_sp               ; Top of Stack
  8.                 DCD     Reset_Handler              ; Reset Handler
  9.                 DCD     NMI_Handler                ; NMI Handler
  10.                 DCD     HardFault_Handler          ; Hard Fault Handler
  11.                 DCD     MemManage_Handler          ; MPU Fault Handler
  12.                 DCD     BusFault_Handler           ; Bus Fault Handler
  13.                 DCD     UsageFault_Handler         ; Usage Fault Handler
  14.                 DCD     0                          ; Reserved
  15.                 DCD     0                          ; Reserved
  16.                 DCD     0                          ; Reserved
  17.                 DCD     0                          ; Reserved
  18.                 DCD     SVC_Handler                ; SVCall Handler
  19.                 DCD     DebugMon_Handler           ; Debug Monitor Handler
  20.                 DCD     0                          ; Reserved
  21.                 DCD     PendSV_Handler             ; PendSV Handler
  22.                 DCD     SysTick_Handler            ; SysTick Handler
  23.  
  24.                 ; External Interrupts
  25.                 DCD     WWDG_IRQHandler            ; Window Watchdog
  26.                 DCD     PVD_IRQHandler             ; PVD through EXTI Line detect
  27.                 DCD     TAMPER_IRQHandler          ; Tamper
  28.                 DCD     RTC_IRQHandler             ; RTC
  29.                 DCD     FLASH_IRQHandler           ; Flash
  30.                 DCD     RCC_IRQHandler             ; RCC
  31.                 DCD     EXTI0_IRQHandler           ; EXTI Line 0
  32.                 DCD     EXTI1_IRQHandler           ; EXTI Line 1
  33.                 DCD     EXTI2_IRQHandler           ; EXTI Line 2
  34.                 DCD     EXTI3_IRQHandler           ; EXTI Line 3
  35.                 DCD     EXTI4_IRQHandler           ; EXTI Line 4
  36.                 DCD     DMA1_Channel1_IRQHandler   ; DMA1 Channel 1
  37.                 DCD     DMA1_Channel2_IRQHandler   ; DMA1 Channel 2
  38.                 DCD     DMA1_Channel3_IRQHandler   ; DMA1 Channel 3
  39.                 DCD     DMA1_Channel4_IRQHandler   ; DMA1 Channel 4
  40.                 DCD     DMA1_Channel5_IRQHandler   ; DMA1 Channel 5
  41.                 DCD     DMA1_Channel6_IRQHandler   ; DMA1 Channel 6
  42.                 DCD     DMA1_Channel7_IRQHandler   ; DMA1 Channel 7
  43.                 DCD     ADC1_2_IRQHandler          ; ADC1 & ADC2
  44.                 DCD     USB_HP_CAN1_TX_IRQHandler  ; USB High Priority or CAN1 TX
  45.                 DCD     USB_LP_CAN1_RX0_IRQHandler ; USB Low  Priority or CAN1 RX0
  46.                 DCD     CAN1_RX1_IRQHandler        ; CAN1 RX1
  47.                 DCD     CAN1_SCE_IRQHandler        ; CAN1 SCE
  48.                 DCD     EXTI9_5_IRQHandler         ; EXTI Line 9..5
  49.                 DCD     TIM1_BRK_IRQHandler        ; TIM1 Break
  50.                 DCD     TIM1_UP_IRQHandler         ; TIM1 Update
  51.                 DCD     TIM1_TRG_COM_IRQHandler    ; TIM1 Trigger and Commutation
  52.                 DCD     TIM1_CC_IRQHandler         ; TIM1 Capture Compare
  53.                 DCD     TIM2_IRQHandler            ; TIM2
  54.                 DCD     TIM3_IRQHandler            ; TIM3
  55.                 DCD     TIM4_IRQHandler            ; TIM4
  56.                 DCD     I2C1_EV_IRQHandler         ; I2C1 Event
  57.                 DCD     I2C1_ER_IRQHandler         ; I2C1 Error
  58.                 DCD     I2C2_EV_IRQHandler         ; I2C2 Event
  59.                 DCD     I2C2_ER_IRQHandler         ; I2C2 Error
  60.                 DCD     SPI1_IRQHandler            ; SPI1
  61.                 DCD     SPI2_IRQHandler            ; SPI2
  62.                 DCD     USART1_IRQHandler          ; USART1
  63.                 DCD     USART2_IRQHandler          ; USART2
  64.                 DCD     USART3_IRQHandler          ; USART3
  65.                 DCD     EXTI15_10_IRQHandler       ; EXTI Line 15..10
  66.                 DCD     RTC_Alarm_IRQHandler        ; RTC Alarm through EXTI Line
  67.                 DCD     USBWakeUp_IRQHandler       ; USB Wakeup from suspend
  68.                 DCD     TIM8_BRK_IRQHandler        ; TIM8 Break
  69.                 DCD     TIM8_UP_IRQHandler         ; TIM8 Update
  70.                 DCD     TIM8_TRG_COM_IRQHandler    ; TIM8 Trigger and Commutation
  71.                 DCD     TIM8_CC_IRQHandler         ; TIM8 Capture Compare
  72.                 DCD     ADC3_IRQHandler            ; ADC3
  73.                 DCD     FSMC_IRQHandler            ; FSMC
  74.                 DCD     SDIO_IRQHandler            ; SDIO
  75.                 DCD     TIM5_IRQHandler            ; TIM5
  76.                 DCD     SPI3_IRQHandler            ; SPI3
  77.                 DCD     UART4_IRQHandler           ; UART4
  78.                 DCD     UART5_IRQHandler           ; UART5
  79.                 DCD     TIM6_IRQHandler            ; TIM6
  80.                 DCD     TIM7_IRQHandler            ; TIM7
  81.                 DCD     DMA2_Channel1_IRQHandler   ; DMA2 Channel1
  82.                 DCD     DMA2_Channel2_IRQHandler   ; DMA2 Channel2
  83.                 DCD     DMA2_Channel3_IRQHandler   ; DMA2 Channel3
  84.                 DCD     DMA2_Channel4_5_IRQHandler ; DMA2 Channel4 & Channel5
  85. __Vectors_End
  86.  
  87. __Vectors_Size  EQU  __Vectors_End - __Vectors

        首先定义了一块名为RESET的内存区域，该区域存储数据且是只读的。 

        随后导出了三个标号__Vectors、__Vectors_End和__Vectors_Size，以便其他文件中引用它们。

         从标号__Vectors开始，使用DCD指令定义了多个中断函数的地址（包括系统内核中断和外部中断两类），可以看出最低地址存放着栈顶的初始化地址即__initial_sp。最后用__Vectors_End标号表示向量表的结束并计算出标号__Vectors_Size的值。

6、定义默认中断函数

  1.                 AREA    |.text|, CODE, READONLY
  2.                 
  3. ; Reset handler
  4. Reset_Handler   PROC
  5.                 EXPORT  Reset_Handler             [WEAK]
  6.                 IMPORT  __main
  7.                 IMPORT  SystemInit
  8.                 LDR     R0, =SystemInit
  9.                 BLX     R0               
  10.                 LDR     R0, =__main
  11.                 BX      R0
  12.                 ENDP
  13.                 
  14. ; Dummy Exception Handlers (infinite loops which can be modified)
  15.  
  16. NMI_Handler     PROC
  17.                 EXPORT  NMI_Handler                [WEAK]
  18.                 B       .
  19.                 ENDP
  20. HardFault_Handler\
  21.                 PROC
  22.                 EXPORT  HardFault_Handler          [WEAK]
  23.                 B       .
  24.                 ENDP
  25. MemManage_Handler\
  26.                 PROC
  27.                 EXPORT  MemManage_Handler          [WEAK]
  28.                 B       .
  29.                 ENDP
  30. BusFault_Handler\
  31.                 PROC
  32.                 EXPORT  BusFault_Handler           [WEAK]
  33.                 B       .
  34.                 ENDP
  35. UsageFault_Handler\
  36.                 PROC
  37.                 EXPORT  UsageFault_Handler         [WEAK]
  38.                 B       .
  39.                 ENDP
  40. SVC_Handler     PROC
  41.                 EXPORT  SVC_Handler                [WEAK]
  42.                 B       .
  43.                 ENDP
  44. DebugMon_Handler\
  45.                 PROC
  46.                 EXPORT  DebugMon_Handler           [WEAK]
  47.                 B       .
  48.                 ENDP
  49. PendSV_Handler  PROC
  50.                 EXPORT  PendSV_Handler             [WEAK]
  51.                 B       .
  52.                 ENDP
  53. SysTick_Handler PROC
  54.                 EXPORT  SysTick_Handler            [WEAK]
  55.                 B       .
  56.                 ENDP
  57.  
  58. Default_Handler PROC
  59.  
  60.                 EXPORT  WWDG_IRQHandler            [WEAK]
  61.                 EXPORT  PVD_IRQHandler             [WEAK]
  62.                 EXPORT  TAMPER_IRQHandler          [WEAK]
  63.                 EXPORT  RTC_IRQHandler             [WEAK]
  64.                 EXPORT  FLASH_IRQHandler           [WEAK]
  65.                 EXPORT  RCC_IRQHandler             [WEAK]
  66.                 EXPORT  EXTI0_IRQHandler           [WEAK]
  67.                 EXPORT  EXTI1_IRQHandler           [WEAK]
  68.                 EXPORT  EXTI2_IRQHandler           [WEAK]
  69.                 EXPORT  EXTI3_IRQHandler           [WEAK]
  70.                 EXPORT  EXTI4_IRQHandler           [WEAK]
  71.                 EXPORT  DMA1_Channel1_IRQHandler   [WEAK]
  72.                 EXPORT  DMA1_Channel2_IRQHandler   [WEAK]
  73.                 EXPORT  DMA1_Channel3_IRQHandler   [WEAK]
  74.                 EXPORT  DMA1_Channel4_IRQHandler   [WEAK]
  75.                 EXPORT  DMA1_Channel5_IRQHandler   [WEAK]
  76.                 EXPORT  DMA1_Channel6_IRQHandler   [WEAK]
  77.                 EXPORT  DMA1_Channel7_IRQHandler   [WEAK]
  78.                 EXPORT  ADC1_2_IRQHandler          [WEAK]
  79.                 EXPORT  USB_HP_CAN1_TX_IRQHandler  [WEAK]
  80.                 EXPORT  USB_LP_CAN1_RX0_IRQHandler [WEAK]
  81.                 EXPORT  CAN1_RX1_IRQHandler        [WEAK]
  82.                 EXPORT  CAN1_SCE_IRQHandler        [WEAK]
  83.                 EXPORT  EXTI9_5_IRQHandler         [WEAK]
  84.                 EXPORT  TIM1_BRK_IRQHandler        [WEAK]
  85.                 EXPORT  TIM1_UP_IRQHandler         [WEAK]
  86.                 EXPORT  TIM1_TRG_COM_IRQHandler    [WEAK]
  87.                 EXPORT  TIM1_CC_IRQHandler         [WEAK]
  88.                 EXPORT  TIM2_IRQHandler            [WEAK]
  89.                 EXPORT  TIM3_IRQHandler            [WEAK]
  90.                 EXPORT  TIM4_IRQHandler            [WEAK]
  91.                 EXPORT  I2C1_EV_IRQHandler         [WEAK]
  92.                 EXPORT  I2C1_ER_IRQHandler         [WEAK]
  93.                 EXPORT  I2C2_EV_IRQHandler         [WEAK]
  94.                 EXPORT  I2C2_ER_IRQHandler         [WEAK]
  95.                 EXPORT  SPI1_IRQHandler            [WEAK]
  96.                 EXPORT  SPI2_IRQHandler            [WEAK]
  97.                 EXPORT  USART1_IRQHandler          [WEAK]
  98.                 EXPORT  USART2_IRQHandler          [WEAK]
  99.                 EXPORT  USART3_IRQHandler          [WEAK]
  100.                 EXPORT  EXTI15_10_IRQHandler       [WEAK]
  101.                 EXPORT  RTC_Alarm_IRQHandler        [WEAK]
  102.                 EXPORT  USBWakeUp_IRQHandler       [WEAK]
  103.                 EXPORT  TIM8_BRK_IRQHandler        [WEAK]
  104.                 EXPORT  TIM8_UP_IRQHandler         [WEAK]
  105.                 EXPORT  TIM8_TRG_COM_IRQHandler    [WEAK]
  106.                 EXPORT  TIM8_CC_IRQHandler         [WEAK]
  107.                 EXPORT  ADC3_IRQHandler            [WEAK]
  108.                 EXPORT  FSMC_IRQHandler            [WEAK]
  109.                 EXPORT  SDIO_IRQHandler            [WEAK]
  110.                 EXPORT  TIM5_IRQHandler            [WEAK]
  111.                 EXPORT  SPI3_IRQHandler            [WEAK]
  112.                 EXPORT  UART4_IRQHandler           [WEAK]
  113.                 EXPORT  UART5_IRQHandler           [WEAK]
  114.                 EXPORT  TIM6_IRQHandler            [WEAK]
  115.                 EXPORT  TIM7_IRQHandler            [WEAK]
  116.                 EXPORT  DMA2_Channel1_IRQHandler   [WEAK]
  117.                 EXPORT  DMA2_Channel2_IRQHandler   [WEAK]
  118.                 EXPORT  DMA2_Channel3_IRQHandler   [WEAK]
  119.                 EXPORT  DMA2_Channel4_5_IRQHandler [WEAK]
  120.  
  121. WWDG_IRQHandler
  122. PVD_IRQHandler
  123. TAMPER_IRQHandler
  124. RTC_IRQHandler
  125. FLASH_IRQHandler
  126. RCC_IRQHandler
  127. EXTI0_IRQHandler
  128. EXTI1_IRQHandler
  129. EXTI2_IRQHandler
  130. EXTI3_IRQHandler
  131. EXTI4_IRQHandler
  132. DMA1_Channel1_IRQHandler
  133. DMA1_Channel2_IRQHandler
  134. DMA1_Channel3_IRQHandler
  135. DMA1_Channel4_IRQHandler
  136. DMA1_Channel5_IRQHandler
  137. DMA1_Channel6_IRQHandler
  138. DMA1_Channel7_IRQHandler
  139. ADC1_2_IRQHandler
  140. USB_HP_CAN1_TX_IRQHandler
  141. USB_LP_CAN1_RX0_IRQHandler
  142. CAN1_RX1_IRQHandler
  143. CAN1_SCE_IRQHandler
  144. EXTI9_5_IRQHandler
  145. TIM1_BRK_IRQHandler
  146. TIM1_UP_IRQHandler
  147. TIM1_TRG_COM_IRQHandler
  148. TIM1_CC_IRQHandler
  149. TIM2_IRQHandler
  150. TIM3_IRQHandler
  151. TIM4_IRQHandler
  152. I2C1_EV_IRQHandler
  153. I2C1_ER_IRQHandler
  154. I2C2_EV_IRQHandler
  155. I2C2_ER_IRQHandler
  156. SPI1_IRQHandler
  157. SPI2_IRQHandler
  158. USART1_IRQHandler
  159. USART2_IRQHandler
  160. USART3_IRQHandler
  161. EXTI15_10_IRQHandler
  162. RTC_Alarm_IRQHandler
  163. USBWakeUp_IRQHandler
  164. TIM8_BRK_IRQHandler
  165. TIM8_UP_IRQHandler
  166. TIM8_TRG_COM_IRQHandler
  167. TIM8_CC_IRQHandler
  168. ADC3_IRQHandler
  169. FSMC_IRQHandler
  170. SDIO_IRQHandler
  171. TIM5_IRQHandler
  172. SPI3_IRQHandler
  173. UART4_IRQHandler
  174. UART5_IRQHandler
  175. TIM6_IRQHandler
  176. TIM7_IRQHandler
  177. DMA2_Channel1_IRQHandler
  178. DMA2_Channel2_IRQHandler
  179. DMA2_Channel3_IRQHandler
  180. DMA2_Channel4_5_IRQHandler
  181.                 B       .
  182.  
  183.                 ENDP
  184.  
  185.                 ALIGN

        首先定义了一块名为.text的内存区域，该区域存储代码且是只读的。 

6.1、复位中断函数

  1. ; Reset handler
  2. Reset_Handler   PROC
  3.                 EXPORT  Reset_Handler             [WEAK]
  4.                 IMPORT  __main
  5.                 IMPORT  SystemInit
  6.                 LDR     R0, =SystemInit
  7.                 BLX     R0               
  8.                 LDR     R0, =__main
  9.                 BX      R0
  10.                 ENDP

        定义了一个名为Reset_Handler的标号，PROC表示这是一个过程（即函数），随后Reset_Handler标号被导出并被标记为弱标号，即如果没有在其他地方提供Reset_Handler，则会使用这里定义的弱定义。两个IMPORT语句表示__main和SystemInit标号来自于其他文件，随后使用LDR和BLX指令配合，跳转执行SystemInit函数，它是一个系统初始化函数，在system_stm32f1xx.c中定义，用于配置硬件（如时钟、外设等）。最后跳转执行__main函数，它是一个C库函数，它用于初始化程序的各个段和寄存器，并最终执行用户定义的main函数。其中BX指令不会保存当前PC，即__main函数不会返回。

6.2、其他系统内核中断函数

  1. ; Dummy Exception Handlers (infinite loops which can be modified)
  2.  
  3. NMI_Handler     PROC
  4.                 EXPORT  NMI_Handler                [WEAK]
  5.                 B       .
  6.                 ENDP
  7. HardFault_Handler\
  8.                 PROC
  9.                 EXPORT  HardFault_Handler          [WEAK]
  10.                 B       .
  11.                 ENDP
  12. MemManage_Handler\
  13.                 PROC
  14.                 EXPORT  MemManage_Handler          [WEAK]
  15.                 B       .
  16.                 ENDP
  17. BusFault_Handler\
  18.                 PROC
  19.                 EXPORT  BusFault_Handler           [WEAK]
  20.                 B       .
  21.                 ENDP
  22. UsageFault_Handler\
  23.                 PROC
  24.                 EXPORT  UsageFault_Handler         [WEAK]
  25.                 B       .
  26.                 ENDP
  27. SVC_Handler     PROC
  28.                 EXPORT  SVC_Handler                [WEAK]
  29.                 B       .
  30.                 ENDP
  31. DebugMon_Handler\
  32.                 PROC
  33.                 EXPORT  DebugMon_Handler           [WEAK]
  34.                 B       .
  35.                 ENDP
  36. PendSV_Handler  PROC
  37.                 EXPORT  PendSV_Handler             [WEAK]
  38.                 B       .
  39.                 ENDP
  40. SysTick_Handler PROC
  41.                 EXPORT  SysTick_Handler            [WEAK]
  42.                 B       .
  43.                 ENDP

        其他的系统内核中断函数的函数定义都是一个无限循环B .，开发者需要在其他地方为这些函数提供实际的实现。

6.3、外部中断函数

  1. Default_Handler PROC
  2.  
  3.                 EXPORT  WWDG_IRQHandler            [WEAK]
  4.                 EXPORT  PVD_IRQHandler             [WEAK]
  5.                 EXPORT  TAMPER_IRQHandler          [WEAK]
  6.                 EXPORT  RTC_IRQHandler             [WEAK]
  7.                 EXPORT  FLASH_IRQHandler           [WEAK]
  8.                 EXPORT  RCC_IRQHandler             [WEAK]
  9.                 EXPORT  EXTI0_IRQHandler           [WEAK]
  10.                 EXPORT  EXTI1_IRQHandler           [WEAK]
  11.                 EXPORT  EXTI2_IRQHandler           [WEAK]
  12.                 EXPORT  EXTI3_IRQHandler           [WEAK]
  13.                 EXPORT  EXTI4_IRQHandler           [WEAK]
  14.                 EXPORT  DMA1_Channel1_IRQHandler   [WEAK]
  15.                 EXPORT  DMA1_Channel2_IRQHandler   [WEAK]
  16.                 EXPORT  DMA1_Channel3_IRQHandler   [WEAK]
  17.                 EXPORT  DMA1_Channel4_IRQHandler   [WEAK]
  18.                 EXPORT  DMA1_Channel5_IRQHandler   [WEAK]
  19.                 EXPORT  DMA1_Channel6_IRQHandler   [WEAK]
  20.                 EXPORT  DMA1_Channel7_IRQHandler   [WEAK]
  21.                 EXPORT  ADC1_2_IRQHandler          [WEAK]
  22.                 EXPORT  USB_HP_CAN1_TX_IRQHandler  [WEAK]
  23.                 EXPORT  USB_LP_CAN1_RX0_IRQHandler [WEAK]
  24.                 EXPORT  CAN1_RX1_IRQHandler        [WEAK]
  25.                 EXPORT  CAN1_SCE_IRQHandler        [WEAK]
  26.                 EXPORT  EXTI9_5_IRQHandler         [WEAK]
  27.                 EXPORT  TIM1_BRK_IRQHandler        [WEAK]
  28.                 EXPORT  TIM1_UP_IRQHandler         [WEAK]
  29.                 EXPORT  TIM1_TRG_COM_IRQHandler    [WEAK]
  30.                 EXPORT  TIM1_CC_IRQHandler         [WEAK]
  31.                 EXPORT  TIM2_IRQHandler            [WEAK]
  32.                 EXPORT  TIM3_IRQHandler            [WEAK]
  33.                 EXPORT  TIM4_IRQHandler            [WEAK]
  34.                 EXPORT  I2C1_EV_IRQHandler         [WEAK]
  35.                 EXPORT  I2C1_ER_IRQHandler         [WEAK]
  36.                 EXPORT  I2C2_EV_IRQHandler         [WEAK]
  37.                 EXPORT  I2C2_ER_IRQHandler         [WEAK]
  38.                 EXPORT  SPI1_IRQHandler            [WEAK]
  39.                 EXPORT  SPI2_IRQHandler            [WEAK]
  40.                 EXPORT  USART1_IRQHandler          [WEAK]
  41.                 EXPORT  USART2_IRQHandler          [WEAK]
  42.                 EXPORT  USART3_IRQHandler          [WEAK]
  43.                 EXPORT  EXTI15_10_IRQHandler       [WEAK]
  44.                 EXPORT  RTC_Alarm_IRQHandler        [WEAK]
  45.                 EXPORT  USBWakeUp_IRQHandler       [WEAK]
  46.                 EXPORT  TIM8_BRK_IRQHandler        [WEAK]
  47.                 EXPORT  TIM8_UP_IRQHandler         [WEAK]
  48.                 EXPORT  TIM8_TRG_COM_IRQHandler    [WEAK]
  49.                 EXPORT  TIM8_CC_IRQHandler         [WEAK]
  50.                 EXPORT  ADC3_IRQHandler            [WEAK]
  51.                 EXPORT  FSMC_IRQHandler            [WEAK]
  52.                 EXPORT  SDIO_IRQHandler            [WEAK]
  53.                 EXPORT  TIM5_IRQHandler            [WEAK]
  54.                 EXPORT  SPI3_IRQHandler            [WEAK]
  55.                 EXPORT  UART4_IRQHandler           [WEAK]
  56.                 EXPORT  UART5_IRQHandler           [WEAK]
  57.                 EXPORT  TIM6_IRQHandler            [WEAK]
  58.                 EXPORT  TIM7_IRQHandler            [WEAK]
  59.                 EXPORT  DMA2_Channel1_IRQHandler   [WEAK]
  60.                 EXPORT  DMA2_Channel2_IRQHandler   [WEAK]
  61.                 EXPORT  DMA2_Channel3_IRQHandler   [WEAK]
  62.                 EXPORT  DMA2_Channel4_5_IRQHandler [WEAK]
  63.  
  64. WWDG_IRQHandler
  65. PVD_IRQHandler
  66. TAMPER_IRQHandler
  67. RTC_IRQHandler
  68. FLASH_IRQHandler
  69. RCC_IRQHandler
  70. EXTI0_IRQHandler
  71. EXTI1_IRQHandler
  72. EXTI2_IRQHandler
  73. EXTI3_IRQHandler
  74. EXTI4_IRQHandler
  75. DMA1_Channel1_IRQHandler
  76. DMA1_Channel2_IRQHandler
  77. DMA1_Channel3_IRQHandler
  78. DMA1_Channel4_IRQHandler
  79. DMA1_Channel5_IRQHandler
  80. DMA1_Channel6_IRQHandler
  81. DMA1_Channel7_IRQHandler
  82. ADC1_2_IRQHandler
  83. USB_HP_CAN1_TX_IRQHandler
  84. USB_LP_CAN1_RX0_IRQHandler
  85. CAN1_RX1_IRQHandler
  86. CAN1_SCE_IRQHandler
  87. EXTI9_5_IRQHandler
  88. TIM1_BRK_IRQHandler
  89. TIM1_UP_IRQHandler
  90. TIM1_TRG_COM_IRQHandler
  91. TIM1_CC_IRQHandler
  92. TIM2_IRQHandler
  93. TIM3_IRQHandler
  94. TIM4_IRQHandler
  95. I2C1_EV_IRQHandler
  96. I2C1_ER_IRQHandler
  97. I2C2_EV_IRQHandler
  98. I2C2_ER_IRQHandler
  99. SPI1_IRQHandler
  100. SPI2_IRQHandler
  101. USART1_IRQHandler
  102. USART2_IRQHandler
  103. USART3_IRQHandler
  104. EXTI15_10_IRQHandler
  105. RTC_Alarm_IRQHandler
  106. USBWakeUp_IRQHandler
  107. TIM8_BRK_IRQHandler
  108. TIM8_UP_IRQHandler
  109. TIM8_TRG_COM_IRQHandler
  110. TIM8_CC_IRQHandler
  111. ADC3_IRQHandler
  112. FSMC_IRQHandler
  113. SDIO_IRQHandler
  114. TIM5_IRQHandler
  115. SPI3_IRQHandler
  116. UART4_IRQHandler
  117. UART5_IRQHandler
  118. TIM6_IRQHandler
  119. TIM7_IRQHandler
  120. DMA2_Channel1_IRQHandler
  121. DMA2_Channel2_IRQHandler
  122. DMA2_Channel3_IRQHandler
  123. DMA2_Channel4_5_IRQHandler
  124.                 B       .
  125.  
  126.                 ENDP

        定义了一个名为Default_Handler的标号，PROC表示这是一个过程（即函数），外部中断函数的标号被导出并被标记为弱标号，它们表示的地址实际上就是Default_Handler函数的地址，如果没有在其他地方对这些外部中断函数进行实现，依旧是会进入无限循环B .。

7、堆栈初始化函数

  1.                 ALIGN
  2.  
  3. ;*******************************************************************************
  4. ; User Stack and Heap initialization
  5. ;*******************************************************************************
  6.                  IF      :DEF:__MICROLIB
  7.                 
  8.                  EXPORT  __initial_sp
  9.                  EXPORT  __heap_base
  10.                  EXPORT  __heap_limit
  11.                 
  12.                  ELSE
  13.                 
  14.                  IMPORT  __use_two_region_memory
  15.                  EXPORT  __user_initial_stackheap
  16.                  
  17. __user_initial_stackheap
  18.  
  19.                  LDR     R0, =  Heap_Mem
  20.                  LDR     R1, = (Stack_Mem + Stack_Size)
  21.                  LDR     R2, = (Heap_Mem +  Heap_Size)
  22.                  LDR     R3, = Stack_Mem
  23.                  BX      LR
  24.  
  25.                  ALIGN
  26.  
  27.                  ENDIF
  28.  
  29.                  END

        ALIGN表示将当前位置对齐到4字节。随后是一段条件编译的代码，如果定义了__MICROLIB宏，则将标号__initial_sp、__heap_base和__heap_limit导出；否则导入__use_two_region_memory标号并导出__user_initial_stackheap标号，其中在R0寄存器保存了堆起始地址，R1寄存器保存了栈顶地址，R2保存了堆结束地址，R3保存了栈的地址。最后跳转到标号LR处继续执行且不返回。

        定义__MICROLIB可以通过Option选项卡进行，如图1所示。

图1 使用微库选项

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注：本文转载自blog.csdn.net的日晨难再的文章"https://blog.csdn.net/weixin_45791458/article/details/142907328"。版权归原作者所有，此博客不拥有其著作权，亦不承担相应法律责任。如有侵权，请联系我们删除。
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