STM32 标准库V3.5启动文件startup

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文章目录

- layout: post tags: [STM32] comments: true
- 前言
- 分析startup_stm32f10x_md.s
- - 汇编指令
  - - EQU
    - AREA
    - SPACE
    - DCD
    - PROC
    - LDR
    - 常见的转移指令
  - 源码分析

前言

这里以stm32f103为硬件平台，搭建了stm32f1系列的标准库，版本是V3.5,在路径标准库的源码路径下Libraries\CMSIS\CM3\DeviceSupport\ST\STM32F10x\startup包含了各个编译器或者说IDE的启动文件：
这些IDE分别是arm，gcc_ride7,iar,TrueSTUDIO,不过这不是关注的重点，本文主要分析startup_stm32f10x_md.s。

分析startup_stm32f10x_md.s

首先看一下arm文件夹下的文件，具体如下；

-ar---        2011/3/10     10:52          15766 startup_stm32f10x_cl.s
-ar---        2011/3/10     10:52          15503 startup_stm32f10x_hd.s
-ar---        2011/3/10     10:52          15692 startup_stm32f10x_hd_vl.s
-ar---        2011/3/10     10:52          12376 startup_stm32f10x_ld.s
-ar---        2011/3/10     10:52          13656 startup_stm32f10x_ld_vl.s
-ar---        2011/3/10     10:52          12765 startup_stm32f10x_md.s
-ar---        2011/3/10     10:51          14073 startup_stm32f10x_md_vl.s
-ar---        2011/3/10     10:51          15955 startup_stm32f10x_xl.s

这里可以看到文件最终加以区分的是xl,md_vl,md等等，这些需要根据芯片具体的容量不同进行选择；
下面看一下startup_stm32f10x_md.s的汇编代码另外一般用户的代码都是从main()函数开始的，但是在此之前，则有启动代码初始化化硬件环境，然后跳转到 c runtime lib的__main中，进行运行环境的初始化，包括栈，堆等等，最终跳转到用户的main函数中。这里没有找到c runtime lib的源码，着实有点遗憾。

在分析源码之前，有必要对部分汇编指令进行简单的了解，这里参考了《Cortex_M3权威指南》

汇编指令

EQU

将一个变量赋值，例如：Stack_Size EQU 0x00000400|

AREA

用于定义一个代码段或数据段,具体用法如：AREA 段名称 {,参数1} {,参数2}...

SPACE

用于申请一片内存空间但不赋初值，例如：Stack_Mem SPACE 0x00000400,分配1024字节的内存控制，感觉相当于malloc，Stack_Mem应该会该内存空间的首地址；

DCD

用于分配一片连续的字存储单元并用伪指令中指定的表达式初始化

PROC

该伪指令用于定义子程序，位置在子程序的开始处，它和ENDP分别表示子程序定义的开始和结束两者必须成对出现;

LDR

从存储器中加载字到一个寄存器中，Load Data to Register

常见的转移指令

B Label 跳转到 Label 处对应的地址
BX reg 跳转到由寄存器 reg 给出的地址
BL Label 跳转到 Label 对应的地址，并且把跳转前的下条指令地址保存到 LR
BLX reg 跳转到由寄存器 reg 给出的地址，并根据 REG 的 LSB 切换处理器状态，还要把转移前的下条指令地址保存到 LR

LR（Link Register），连接寄存器的英文缩写，在ARM体系结构中LR的特殊用途有两种：
一是用来保存子程序返回地址；
二是当异常发生时，LR中保存的值等于异常发生时PC的值减4（或者减2），因此在各种异常模式下可以根据LR的值返回到异常发生前的相应位置继续执行。

源码分析

下面参考一下startup_stm32f10x_md.s的源码，进行分析一下。

;******************** (C) COPYRIGHT 2011 STMicroelectronics ********************
;* File Name          : startup_stm32f10x_md.s
;* Author             : MCD Application Team
;* Version            : V3.5.0
;* Date               : 11-March-2011
;* Description        : STM32F10x Medium Density Devices vector table for MDK-ARM 
;*                      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 CortexM3 processor is in Thread mode,
;*                      priority is Privileged, and the Stack is set to Main.
;* <<< Use Configuration Wizard in Context Menu >>>   
;*******************************************************************************
; THE PRESENT FIRMWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS
; WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE TIME.
; AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY DIRECT,
; INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING FROM THE
; CONTENT OF SUCH FIRMWARE AND/OR THE USE MADE BY CUSTOMERS OF THE CODING
; INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
;*******************************************************************************; Amount of memory (in bytes) allocated for Stack
; Tailor this value to your application needs
; <h> Stack Configuration
;   <o> Stack Size (in Bytes) <0x0-0xFFFFFFFF:8>
; </h>
Stack_Size      EQU     0x00000400  ;栈空间 1024 Bytes，1K的空间;分配数据段，命名为`STACK`,数据段未初始化,可以读写AREA    STACK, NOINIT, READWRITE, ALIGN=3   ;
Stack_Mem       SPACE   Stack_Size
__initial_sp; <h> Heap Configuration
;   <o>  Heap Size (in Bytes) <0x0-0xFFFFFFFF:8>
; </h>Heap_Size       EQU     0x00000200  ;堆空间的配置，512 字节的空间AREA    HEAP, NOINIT, READWRITE, ALIGN=3
__heap_base
Heap_Mem        SPACE   Heap_Size   ;分配堆空间为 512字节
__heap_limitPRESERVE8THUMB; Vector Table Mapped to Address 0 at Reset
;向量表映射到地址0x00000000AREA    RESET, DATA, READONLYEXPORT  __Vectors       ;导出__Vectors符号，用于外部文件的使用EXPORT  __Vectors_End   ;导出向量表的结束地址EXPORT  __Vectors_Size  ;导出向量表的大小;使用DCD为__initial_sp以及异常地址分配内存空间，存到向量表中
__Vectors       DCD     __initial_sp               ; Top of StackDCD     Reset_Handler              ; Reset HandlerDCD     NMI_Handler                ; NMI HandlerDCD     HardFault_Handler          ; Hard Fault HandlerDCD     MemManage_Handler          ; MPU Fault HandlerDCD     BusFault_Handler           ; Bus Fault HandlerDCD     UsageFault_Handler         ; Usage Fault HandlerDCD     0                          ; ReservedDCD     0                          ; ReservedDCD     0                          ; ReservedDCD     0                          ; ReservedDCD     SVC_Handler                ; SVCall HandlerDCD     DebugMon_Handler           ; Debug Monitor HandlerDCD     0                          ; ReservedDCD     PendSV_Handler             ; PendSV HandlerDCD     SysTick_Handler            ; SysTick Handler; External Interrupts; 外设的中断地址DCD     WWDG_IRQHandler            ; Window WatchdogDCD     PVD_IRQHandler             ; PVD through EXTI Line detectDCD     TAMPER_IRQHandler          ; TamperDCD     RTC_IRQHandler             ; RTCDCD     FLASH_IRQHandler           ; FlashDCD     RCC_IRQHandler             ; RCCDCD     EXTI0_IRQHandler           ; EXTI Line 0DCD     EXTI1_IRQHandler           ; EXTI Line 1DCD     EXTI2_IRQHandler           ; EXTI Line 2DCD     EXTI3_IRQHandler           ; EXTI Line 3DCD     EXTI4_IRQHandler           ; EXTI Line 4DCD     DMA1_Channel1_IRQHandler   ; DMA1 Channel 1DCD     DMA1_Channel2_IRQHandler   ; DMA1 Channel 2DCD     DMA1_Channel3_IRQHandler   ; DMA1 Channel 3DCD     DMA1_Channel4_IRQHandler   ; DMA1 Channel 4DCD     DMA1_Channel5_IRQHandler   ; DMA1 Channel 5DCD     DMA1_Channel6_IRQHandler   ; DMA1 Channel 6DCD     DMA1_Channel7_IRQHandler   ; DMA1 Channel 7DCD     ADC1_2_IRQHandler          ; ADC1_2DCD     USB_HP_CAN1_TX_IRQHandler  ; USB High Priority or CAN1 TXDCD     USB_LP_CAN1_RX0_IRQHandler ; USB Low  Priority or CAN1 RX0DCD     CAN1_RX1_IRQHandler        ; CAN1 RX1DCD     CAN1_SCE_IRQHandler        ; CAN1 SCEDCD     EXTI9_5_IRQHandler         ; EXTI Line 9..5DCD     TIM1_BRK_IRQHandler        ; TIM1 BreakDCD     TIM1_UP_IRQHandler         ; TIM1 UpdateDCD     TIM1_TRG_COM_IRQHandler    ; TIM1 Trigger and CommutationDCD     TIM1_CC_IRQHandler         ; TIM1 Capture CompareDCD     TIM2_IRQHandler            ; TIM2DCD     TIM3_IRQHandler            ; TIM3DCD     TIM4_IRQHandler            ; TIM4DCD     I2C1_EV_IRQHandler         ; I2C1 EventDCD     I2C1_ER_IRQHandler         ; I2C1 ErrorDCD     I2C2_EV_IRQHandler         ; I2C2 EventDCD     I2C2_ER_IRQHandler         ; I2C2 ErrorDCD     SPI1_IRQHandler            ; SPI1DCD     SPI2_IRQHandler            ; SPI2DCD     USART1_IRQHandler          ; USART1DCD     USART2_IRQHandler          ; USART2DCD     USART3_IRQHandler          ; USART3DCD     EXTI15_10_IRQHandler       ; EXTI Line 15..10DCD     RTCAlarm_IRQHandler        ; RTC Alarm through EXTI LineDCD     USBWakeUp_IRQHandler       ; USB Wakeup from suspend
__Vectors_End__Vectors_Size  EQU  __Vectors_End - __Vectors  ;   计算向量表大小AREA    |.text|, CODE, READONLY ;   分配代码段，只读; Reset handler
Reset_Handler    PROCEXPORT  Reset_Handler             [WEAK]IMPORT  __mainIMPORT  SystemInitLDR     R0, =SystemInitBLX     R0LDR     R0, =__mainBX      R0ENDP; Dummy Exception Handlers (infinite loops which can be modified)
; [WEAK]指令会优先使用外部的链接符号，但是没有原型，编译器也不会出现报错
NMI_Handler     PROCEXPORT  NMI_Handler                [WEAK]B       .ENDP
HardFault_Handler\PROCEXPORT  HardFault_Handler          [WEAK]B       .ENDP
MemManage_Handler\PROCEXPORT  MemManage_Handler          [WEAK]B       .ENDP
BusFault_Handler\PROCEXPORT  BusFault_Handler           [WEAK]B       .ENDP
UsageFault_Handler\PROCEXPORT  UsageFault_Handler         [WEAK]B       .ENDP
SVC_Handler     PROCEXPORT  SVC_Handler                [WEAK]B       .ENDP
DebugMon_Handler\PROCEXPORT  DebugMon_Handler           [WEAK]B       .ENDP
PendSV_Handler  PROCEXPORT  PendSV_Handler             [WEAK]B       .ENDP
SysTick_Handler PROCEXPORT  SysTick_Handler            [WEAK]B       .ENDPDefault_Handler PROCEXPORT  WWDG_IRQHandler            [WEAK]EXPORT  PVD_IRQHandler             [WEAK]EXPORT  TAMPER_IRQHandler          [WEAK]EXPORT  RTC_IRQHandler             [WEAK]EXPORT  FLASH_IRQHandler           [WEAK]EXPORT  RCC_IRQHandler             [WEAK]EXPORT  EXTI0_IRQHandler           [WEAK]EXPORT  EXTI1_IRQHandler           [WEAK]EXPORT  EXTI2_IRQHandler           [WEAK]EXPORT  EXTI3_IRQHandler           [WEAK]EXPORT  EXTI4_IRQHandler           [WEAK]EXPORT  DMA1_Channel1_IRQHandler   [WEAK]EXPORT  DMA1_Channel2_IRQHandler   [WEAK]EXPORT  DMA1_Channel3_IRQHandler   [WEAK]EXPORT  DMA1_Channel4_IRQHandler   [WEAK]EXPORT  DMA1_Channel5_IRQHandler   [WEAK]EXPORT  DMA1_Channel6_IRQHandler   [WEAK]EXPORT  DMA1_Channel7_IRQHandler   [WEAK]EXPORT  ADC1_2_IRQHandler          [WEAK]EXPORT  USB_HP_CAN1_TX_IRQHandler  [WEAK]EXPORT  USB_LP_CAN1_RX0_IRQHandler [WEAK]EXPORT  CAN1_RX1_IRQHandler        [WEAK]EXPORT  CAN1_SCE_IRQHandler        [WEAK]EXPORT  EXTI9_5_IRQHandler         [WEAK]EXPORT  TIM1_BRK_IRQHandler        [WEAK]EXPORT  TIM1_UP_IRQHandler         [WEAK]EXPORT  TIM1_TRG_COM_IRQHandler    [WEAK]EXPORT  TIM1_CC_IRQHandler         [WEAK]EXPORT  TIM2_IRQHandler            [WEAK]EXPORT  TIM3_IRQHandler            [WEAK]EXPORT  TIM4_IRQHandler            [WEAK]EXPORT  I2C1_EV_IRQHandler         [WEAK]EXPORT  I2C1_ER_IRQHandler         [WEAK]EXPORT  I2C2_EV_IRQHandler         [WEAK]EXPORT  I2C2_ER_IRQHandler         [WEAK]EXPORT  SPI1_IRQHandler            [WEAK]EXPORT  SPI2_IRQHandler            [WEAK]EXPORT  USART1_IRQHandler          [WEAK]EXPORT  USART2_IRQHandler          [WEAK]EXPORT  USART3_IRQHandler          [WEAK]EXPORT  EXTI15_10_IRQHandler       [WEAK]EXPORT  RTCAlarm_IRQHandler        [WEAK]EXPORT  USBWakeUp_IRQHandler       [WEAK]WWDG_IRQHandler
PVD_IRQHandler
TAMPER_IRQHandler
RTC_IRQHandler
FLASH_IRQHandler
RCC_IRQHandler
EXTI0_IRQHandler
EXTI1_IRQHandler
EXTI2_IRQHandler
EXTI3_IRQHandler
EXTI4_IRQHandler
DMA1_Channel1_IRQHandler
DMA1_Channel2_IRQHandler
DMA1_Channel3_IRQHandler
DMA1_Channel4_IRQHandler
DMA1_Channel5_IRQHandler
DMA1_Channel6_IRQHandler
DMA1_Channel7_IRQHandler
ADC1_2_IRQHandler
USB_HP_CAN1_TX_IRQHandler
USB_LP_CAN1_RX0_IRQHandler
CAN1_RX1_IRQHandler
CAN1_SCE_IRQHandler
EXTI9_5_IRQHandler
TIM1_BRK_IRQHandler
TIM1_UP_IRQHandler
TIM1_TRG_COM_IRQHandler
TIM1_CC_IRQHandler
TIM2_IRQHandler
TIM3_IRQHandler
TIM4_IRQHandler
I2C1_EV_IRQHandler
I2C1_ER_IRQHandler
I2C2_EV_IRQHandler
I2C2_ER_IRQHandler
SPI1_IRQHandler
SPI2_IRQHandler
USART1_IRQHandler
USART2_IRQHandler
USART3_IRQHandler
EXTI15_10_IRQHandler
RTCAlarm_IRQHandler
USBWakeUp_IRQHandlerB       .ENDPALIGN;*******************************************************************************
; User Stack and Heap initialization
;*******************************************************************************IF      :DEF:__MICROLIB           EXPORT  __initial_spEXPORT  __heap_baseEXPORT  __heap_limitELSEIMPORT  __use_two_region_memoryEXPORT  __user_initial_stackheap__user_initial_stackheapLDR     R0, =  Heap_MemLDR     R1, =(Stack_Mem + Stack_Size)LDR     R2, = (Heap_Mem +  Heap_Size)LDR     R3, = Stack_MemBX      LRALIGNENDIFEND;******************* (C) COPYRIGHT 2011 STMicroelectronics *****END OF FILE*****

主要做了这几个事情：

初始化堆栈内存空间；
设置PC寄存器的地址指向Reset_Handler,即上电便运行复位程序；
设置向量表，中断服务程序入口地址；
配置系统时钟, SystemInit在main函数运行前就已经运行了；
运行外部的函数，LDR R0, =__main，将__main地址装载到R0寄存器并运行，__main在C库中，会初始化程序的C运行环境，最终调用用户的main函数；

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STM32 标准库V3.5启动文件startup_stm32f10xxx.s分析

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