Cortex-m3启动代码分析笔记

1万 · 2013-9-25 15:33

启动代码文件名是STM32F10X.S，它的作用先总结下，然后再分析。启动代码作用一般是：1）堆和栈的初始化；2）向量表定义；3）地址重映射及中断向量表的转移；4）设置系统时钟频率；5）中断寄存器的初始化；6）进入C应用程序。

（1）按启动代码的次序，先看堆和栈的初始化：

Stack_Size EQU 0x00000200 ；定义Stack_Size为0x00000200

AREA STACK, NOINIT, READWRITE, ALIGN=3 ；定义栈，可初始为0，8字节对齐
Stack_Mem SPACE Stack_Size ；分配0x200个连续字节，并初始化为0
__initial_sp ；汇编代码地址标号

Heap_Size EQU 0x00000000

AREA HEAP, NOINIT, READWRITE, ALIGN=3
__heap_base
Heap_Mem SPACE Heap_Size
__heap_limit

PRESERVE8 ；指定当前文件堆栈8字节对齐
THUMB ；告诉汇编器下面是32为的Thumb指令，如果需要汇编器将插入位以保证对齐

1万 · 2013-9-25 15:34

（2）中断向量表定义
AREA RESET, DATA, READONLY ;定义复位向量段，只读
            EXPORT  __Vectors ；定义一个可以在其他文件中使用的全局标号。此处表示中断地址
__Vectors    DCD    __initial_sp             ; 给__initial_sp分配4字节32位的地址0x0
            DCD    Reset_Handler          ; 给标号Reset Handler分配地址为0x00000004
            DCD    NMI_Handler             ; 给标号NMI Handler分配地址0x00000008
            DCD    HardFault_Handler       ; Hard Fault Handler
            DCD    MemManage_Handler       ; MPU Fault Handler
            DCD    BusFault_Handler       ; Bus Fault Handler
            DCD    UsageFault_Handler       ; Usage Fault Handler
            DCD    0                      ; 这种形式就是保留地址，不给任何标号分配
            DCD    0                      ; Reserved
            DCD    0                      ; Reserved
            DCD    0                      ; Reserved
            DCD    SVC_Handler             ; SVCall Handler
            DCD    DebugMon_Handler       ; Debug Monitor Handler
            DCD    0                      ; Reserved
            DCD    PendSV_Handler          ; PendSV Handler
            DCD    SysTick_Handler          ; SysTick Handler
            ; External Interrupts
            DCD    WWDG_IRQHandler          ; Window Watchdog
            DCD    PVD_IRQHandler          ; PVD through EXTI Line detect
            DCD    TAMPER_IRQHandler       ; Tamper
            DCD    RTC_IRQHandler          ; RTC
            DCD    FLASH_IRQHandler       ; Flash
            DCD    RCC_IRQHandler          ; RCC
            DCD    EXTI0_IRQHandler       ; EXTI Line 0
            DCD    EXTI1_IRQHandler       ; EXTI Line 1
            DCD    EXTI2_IRQHandler       ; EXTI Line 2
            DCD    EXTI3_IRQHandler       ; EXTI Line 3

1万 · 2013-9-25 15:35

      DCD    EXTI4_IRQHandler       ; EXTI Line 4
            DCD    DMAChannel1_IRQHandler ; DMA Channel 1
            DCD    DMAChannel2_IRQHandler ; DMA Channel 2
            DCD    DMAChannel3_IRQHandler ; DMA Channel 3
            DCD    DMAChannel4_IRQHandler ; DMA Channel 4
            DCD    DMAChannel5_IRQHandler ; DMA Channel 5
            DCD    DMAChannel6_IRQHandler ; DMA Channel 6
            DCD    DMAChannel7_IRQHandler ; DMA Channel 7
            DCD    ADC_IRQHandler          ; ADC
            DCD    USB_HP_CAN_TX_IRQHandler  ; USB High Priority or CAN TX
            DCD    USB_LP_CAN_RX0_IRQHandler ; USB Low  Priority or CAN RX0
            DCD    CAN_RX1_IRQHandler       ; CAN RX1
            DCD    CAN_SCE_IRQHandler       ; CAN SCE
            DCD    EXTI9_5_IRQHandler       ; EXTI Line 9..5
            DCD    TIM1_BRK_IRQHandler    ; TIM1 Break
            DCD    TIM1_UP_IRQHandler       ; TIM1 Update
            DCD    TIM1_TRG_COM_IRQHandler ; TIM1 Trigger and Commutation
            DCD    TIM1_CC_IRQHandler       ; TIM1 Capture Compare
            DCD    TIM2_IRQHandler          ; TIM2
            DCD    TIM3_IRQHandler          ; TIM3
            DCD    TIM4_IRQHandler          ; TIM4
            DCD    I2C1_EV_IRQHandler       ; I2C1 Event
            DCD    I2C1_ER_IRQHandler       ; I2C1 Error
            DCD    I2C2_EV_IRQHandler       ; I2C2 Event
            DCD    I2C2_ER_IRQHandler       ; I2C2 Error
            DCD    SPI1_IRQHandler          ; SPI1
            DCD    SPI2_IRQHandler          ; SPI2
            DCD    USART1_IRQHandler       ; USART1
            DCD    USART2_IRQHandler       ; USART2
            DCD    USART3_IRQHandler       ; USART3
            DCD    EXTI15_10_IRQHandler    ; EXTI Line 15..10
            DCD    RTCAlarm_IRQHandler    ; RTC Alarm through EXTI Line
            DCD    USBWakeUp_IRQHandler    ; USB Wakeup from suspend

1万 · 2013-9-25 15:37

（3）中断向量表的转移
AREA |.text|, CODE, READONLY ；代码段定义

; Reset Handler
Reset_Handler PROC ；标记一个函数的开始
            EXPORT  Reset_Handler          [WEAK]；[WEAK] 选项表示当所有的源文件都没有定义这样一个标号时，编译器也不给出错误信息，在多数情况下将该标号置为 0 ，若该标号为 B 或 BL 指令引用，则将 B 或 BL指令置为 NOP 操作。EXPORT提示编译器该标号可以为外部文件引用。
            IMPORT  __main ;通知编译器要使用的标号在其他文件
            LDR    R0, =__main；使用“=”表示LDR目前是伪指令不是标准指令。这里是把__main的地址给RO。
            BX    R0；BX是ARM指令集和THUMB指令集之间程序的跳转
            ENDP

; Dummy Exception Handlers (infinite loops which can be modified)
NMI_Handler    m  ;"m"其实就是PROC表示汇编函数的开始
            EXPORT  NMI_Handler             [WEAK]
            B    .
            ENDP
HardFault_Handler\    ;"\"是换行的意思
            PROC
            EXPORT  HardFault_Handler       [WEAK]

1万 · 2013-9-25 15:37

         B    . ;"."号到底是什么含义呢，目前还没查到资料。可能是保留地址，供以后修改的吧
            ENDP
MemManage_Handler\
            PROC
            EXPORT  MemManage_Handler       [WEAK]
            B    .
            ENDP
BusFault_Handler\
            PROC
            EXPORT  BusFault_Handler       [WEAK]
            B    .
            ENDP
UsageFault_Handler\
            PROC
            EXPORT  UsageFault_Handler       [WEAK]
            B    .
            ENDP
SVC_Handler    PROC
            EXPORT  SVC_Handler             [WEAK]
            B    .
            ENDP
DebugMon_Handler\
            PROC
            EXPORT  DebugMon_Handler       [WEAK]
            B    .
            ENDP
PendSV_Handler  PROC
            EXPORT  PendSV_Handler          [WEAK]
            B    .

1万 · 2013-9-25 15:38

            ENDP
SysTick_Handler PROC
            EXPORT  SysTick_Handler          [WEAK]
            B    .
            ENDP
Default_Handler PROC
            EXPORT  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  DMAChannel1_IRQHandler [WEAK]
            EXPORT  DMAChannel2_IRQHandler [WEAK]
            EXPORT  DMAChannel3_IRQHandler [WEAK]
            EXPORT  DMAChannel4_IRQHandler [WEAK]
            EXPORT  DMAChannel5_IRQHandler [WEAK]
            EXPORT  DMAChannel6_IRQHandler [WEAK]
            EXPORT  DMAChannel7_IRQHandler [WEAK]
            EXPORT  ADC_IRQHandler          [WEAK]
            EXPORT  USB_HP_CAN_TX_IRQHandler  [WEAK]
            EXPORT  USB_LP_CAN_RX0_IRQHandler [WEAK]
            EXPORT  CAN_RX1_IRQHandler       [WEAK]

1万 · 2013-9-25 15:38

         EXPORT  CAN_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

1万 · 2013-9-25 15:38

EXTI2_IRQHandler
EXTI3_IRQHandler
EXTI4_IRQHandler
DMAChannel1_IRQHandler
DMAChannel2_IRQHandler
DMAChannel3_IRQHandler
DMAChannel4_IRQHandler
DMAChannel5_IRQHandler
DMAChannel6_IRQHandler
DMAChannel7_IRQHandler
ADC_IRQHandler
USB_HP_CAN_TX_IRQHandler
USB_LP_CAN_RX0_IRQHandler
CAN_RX1_IRQHandler
CAN_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

1万 · 2013-9-25 15:39

USART2_IRQHandler
USART3_IRQHandler
EXTI15_10_IRQHandler
RTCAlarm_IRQHandler
USBWakeUp_IRQHandler
            B    .
ENDP
            ALIGN
  （4）堆和栈的初始化
IF    :DEF:__MICROLIB       ；“DEF”的用法——:DEF:X 就是说X定义了则为真，否则为假

            EXPORT  __initial_sp
            EXPORT  __heap_base
            EXPORT  __heap_limit

            ELSE

            IMPORT  __use_two_region_memory
            EXPORT  __user_initial_stackheap
__user_initial_stackheap
            LDR    R0, =  Heap_Mem
            LDR    R1, =(Stack_Mem + Stack_Size)
            LDR    R2, = (Heap_Mem +  Heap_Size)
            LDR    R3, = Stack_Mem
            BX    LR
            ALIGN ；填充字节使地址对齐
            ENDIF
END