STM32启动文件详解及SystemInit函数分析

 1 ;先在RAM中分配系统使用的栈，RAM的起始地址为0x2000_0000
  2 ;然后在RAM中分配变量使用的堆
  3 ;然后在CODE区(flash)分配中断向量表，flash的起始地址为0x0800_0000，该中断向量表就从这个起始地址开始分配
  4 ;分配完成后，再定义和实现相应的中断函数，
  5 ;所有的中断函数全部带有[weak]特性，即弱定义，如果编译器发现在别处文件中定义了同名函数，在链接时用别处的地址进行链接。
  6 ;中断函数仅仅实现了Reset_Handler,其他要么是死循环，要么仅仅定义了函数名称
  7
  8 ;STM32被设置为从内部FLASH启动时（这也是最常见的一种情况），当STM32遇到复位信号后，
  9 ;从0x0800_0000处取出栈顶地址存放于MSP寄存器，从0x0800_0004处取出复位中断服务入口地址放入PC寄存器，
 10 ;继而执行复位中断服务程序Reset_Handler，
 11 ;Reset_Handler仅仅执行了两个函数调用,一个是SystemInit，另一个__main,
 12 ;SystemInit定义在system_stm32f10x.c中,主要初始化了STM的时钟系统:HSI,HSE,LSI,LSE,PLL,SYSCLK,USBCLK,APECLK等等.
 13 ;__main函数由编译器生成，负责初始化栈、堆等，并在最后跳转到用户自定义的main()函数，来到C的世界。
 14
 15
 16 Stack_Size      EQU     0x00000400  ;//定义堆栈大小
 17                 AREA    STACK, NOINIT, READWRITE, ALIGN=3  ;//定义一个数据段 按8字节对齐    ;AREA 伪指令用于定义一个代码段或数据段 NOINIT：指定此数据段仅仅保留了内存单元，而没有将各初始值写入内存单元，或者将各个内存单元值初始化为0
 18 Stack_Mem       SPACE   Stack_Size    ;//保留Stack_Size大小的堆栈空间 分 配连续 Stack_Size 字节的存储单元并初始化为 0
 19 __initial_sp  ;//标号，代表堆栈顶部地址，后面有用
 20                                                   
 21 ; Heap Configuration
 22 ;     Heap Size (in Bytes) <0x0-0xFFFFFFFF:8>
 23 ;
 24 Heap_Size       EQU     0x00000200    ;//定义堆空间大小
 25                 AREA    HEAP, NOINIT, READWRITE, ALIGN=3  ;//定义一个数据段，8字节对齐
 26 __heap_base      ;//标号，代表堆末底部地址，后面有用
 27 Heap_Mem        SPACE   Heap_Size     ;//保留Heap_Size的堆空间  
 28 __heap_limit     ;//标号，代表堆界限地址，后面有用
 29     ;PRESERVE8 指令指定当前文件保持堆栈八字节对齐。 它设置 PRES8 编译属性以通知链接器。
 30     ;链接器检查要求堆栈八字节对齐的任何代码是否仅由保持堆栈八字节对齐的代码直接或间接地调用。
 31                 PRESERVE8 ;//指示编译器8字节对齐
 32                 THUMB   ;//指示编译器以后的指令为THUMB指令
 33
 34 ;中断向量表定义
 35 ; Vector Table Mapped to Address 0 at Reset
 36                 AREA    RESET, DATA, READONLY   ;//定义只读数据段，其实放在CODE区，位于0地址
 37                 EXPORT  __Vectors    ;EXPORT：在程序中声明一个全局的标号__Vectors，该标号可在其他的文件中引用
 38                 EXPORT  __Vectors_End
 39                 EXPORT  __Vectors_Size
 40 __Vectors       DCD     __initial_sp               ; Top of Stack  ;给__initial_sp分配4字节32位的地址0x0
 41                 DCD     Reset_Handler              ; Reset Handler ; 给标号Reset Handler分配地址为0x00000004
 42                 DCD     NMI_Handler                ; NMI Handler ; 给标号NMI Handler分配地址0x00000008
 43                 DCD     HardFault_Handler          ; Hard Fault Handler
 44                 DCD     MemManage_Handler          ; MPU Fault Handler
 45                 DCD     BusFault_Handler           ; Bus Fault Handler
 46                 DCD     UsageFault_Handler         ; Usage Fault Handler
 47                 DCD     0                          ; Reserved  ; 这种形式就是保留地址，不给任何标号分配
 48                 DCD     0                          ; Reserved
 49                 DCD     0                          ; Reserved
 50                 DCD     0                          ; Reserved
 51                 DCD     SVC_Handler                ; SVCall Handler
 52                 DCD     DebugMon_Handler           ; Debug Monitor Handler
 53                 DCD     0                          ; Reserved
 54                 DCD     PendSV_Handler             ; PendSV Handler
 55                 DCD     SysTick_Handler            ; SysTick Handler
 56                 ; External Interrupts
 57                 DCD     WWDG_IRQHandler            ; Window Watchdog
 58                 DCD     PVD_IRQHandler             ; PVD through EXTI Line detect
 59                 DCD     TAMPER_IRQHandler          ; Tamper
 60                 DCD     RTC_IRQHandler             ; RTC
 61                 DCD     FLASH_IRQHandler           ; Flash
 62                 DCD     RCC_IRQHandler             ; RCC
 63                 DCD     EXTI0_IRQHandler           ; EXTI Line 0
 64                 DCD     EXTI1_IRQHandler           ; EXTI Line 1
 65                 DCD     EXTI2_IRQHandler           ; EXTI Line 2
 66                 DCD     EXTI3_IRQHandler           ; EXTI Line 3
 67                 DCD     EXTI4_IRQHandler           ; EXTI Line 4
 68                 DCD     DMA1_Channel1_IRQHandler   ; DMA1 Channel 1
 69                 DCD     DMA1_Channel2_IRQHandler   ; DMA1 Channel 2
 70                 DCD     DMA1_Channel3_IRQHandler   ; DMA1 Channel 3
 71                 DCD     DMA1_Channel4_IRQHandler   ; DMA1 Channel 4
 72                 DCD     DMA1_Channel5_IRQHandler   ; DMA1 Channel 5
 73                 DCD     DMA1_Channel6_IRQHandler   ; DMA1 Channel 6
 74                 DCD     DMA1_Channel7_IRQHandler   ; DMA1 Channel 7
 75                 DCD     ADC1_2_IRQHandler          ; ADC1 & ADC2
 76                 DCD     USB_HP_CAN1_TX_IRQHandler  ; USB High Priority or CAN1 TX
 77                 DCD     USB_LP_CAN1_RX0_IRQHandler ; USB Low  Priority or CAN1 RX0
 78                 DCD     CAN1_RX1_IRQHandler        ; CAN1 RX1
 79                 DCD     CAN1_SCE_IRQHandler        ; CAN1 SCE
 80                 DCD     EXTI9_5_IRQHandler         ; EXTI Line 9..5
 81                 DCD     TIM1_BRK_IRQHandler        ; TIM1 Break
 82                 DCD     TIM1_UP_IRQHandler         ; TIM1 Update
 83                 DCD     TIM1_TRG_COM_IRQHandler    ; TIM1 Trigger and Commutation
 84                 DCD     TIM1_CC_IRQHandler         ; TIM1 Capture Compare
 85                 DCD     TIM2_IRQHandler            ; TIM2
 86                 DCD     TIM3_IRQHandler            ; TIM3
 87                 DCD     TIM4_IRQHandler            ; TIM4
 88                 DCD     I2C1_EV_IRQHandler         ; I2C1 Event
 89                 DCD     I2C1_ER_IRQHandler         ; I2C1 Error
 90                 DCD     I2C2_EV_IRQHandler         ; I2C2 Event
 91                 DCD     I2C2_ER_IRQHandler         ; I2C2 Error
 92                 DCD     SPI1_IRQHandler            ; SPI1
 93                 DCD     SPI2_IRQHandler            ; SPI2
 94                 DCD     USART1_IRQHandler          ; USART1
 95                 DCD     USART2_IRQHandler          ; USART2
 96                 DCD     USART3_IRQHandler          ; USART3
 97                 DCD     EXTI15_10_IRQHandler       ; EXTI Line 15..10
 98                 DCD     RTCAlarm_IRQHandler        ; RTC Alarm through EXTI Line
 99                 DCD     USBWakeUp_IRQHandler       ; USB Wakeup from suspend
100                 DCD     TIM8_BRK_IRQHandler        ; TIM8 Break
101                 DCD     TIM8_UP_IRQHandler         ; TIM8 Update
102                 DCD     TIM8_TRG_COM_IRQHandler    ; TIM8 Trigger and Commutation
103                 DCD     TIM8_CC_IRQHandler         ; TIM8 Capture Compare
104                 DCD     ADC3_IRQHandler            ; ADC3
105                 DCD     FSMC_IRQHandler            ; FSMC
106                 DCD     SDIO_IRQHandler            ; SDIO
107                 DCD     TIM5_IRQHandler            ; TIM5
108                 DCD     SPI3_IRQHandler            ; SPI3
109                 DCD     UART4_IRQHandler           ; UART4
110                 DCD     UART5_IRQHandler           ; UART5
111                 DCD     TIM6_IRQHandler            ; TIM6
112                 DCD     TIM7_IRQHandler            ; TIM7
113                 DCD     DMA2_Channel1_IRQHandler   ; DMA2 Channel1
114                 DCD     DMA2_Channel2_IRQHandler   ; DMA2 Channel2
115                 DCD     DMA2_Channel3_IRQHandler   ; DMA2 Channel3
116                 DCD     DMA2_Channel4_5_IRQHandler ; DMA2 Channel4 & Channel5
117 __Vectors_End
118 __Vectors_Size  EQU  __Vectors_End - __Vectors
119                 AREA    |.text|, CODE, READONLY ;代码段定义
120
121 ; Reset Handler
122 ;利用PROC、ENDP这一对伪指令把程序段分为若干个过程，使程序的结构加清晰
123 Reset_Handler   PROC   ;过程的开始
124                 EXPORT  Reset_Handler             [WEAK];[WEAK] 弱定义，意思是如果在别处也定义该标号(函数)，在链接时用别处的地址。
125               ;如果没有其它定方定义，编译器也不报错，以此处地址进行链接。
126               ;EXPORT提示编译器该标号可以为外部文件引用。
127                 IMPORT  __main    ;通知编译器要使用的标号在其他文件
128                 IMPORT  SystemInit
129                 LDR     R0, =SystemInit
130                 BLX     R0          ;BX是ARM指令集和THUMB指令集之间程序的跳转     
131                 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。
132                 BX      R0   ;BX是ARM指令集和THUMB指令集之间程序的跳转
133                 ENDP     ;过程的结束
134                 
135 ; Dummy Exception Handlers (infinite loops which can be modified)
136 NMI_Handler     PROC
137                 EXPORT  NMI_Handler                [WEAK]
138                 B       .      ;原地跳转(即无限循环)，
139                 ENDP
140 HardFault_Handler
141                 PROC
142                 EXPORT  HardFault_Handler          [WEAK]
143                 B       .
144                 ENDP
145 MemManage_Handler
146                 PROC
147                 EXPORT  MemManage_Handler          [WEAK]
148                 B       .
149                 ENDP
150 BusFault_Handler
151                 PROC
152                 EXPORT  BusFault_Handler           [WEAK]
153                 B       .
154                 ENDP
155 UsageFault_Handler
156                 PROC
157                 EXPORT  UsageFault_Handler         [WEAK]
158                 B       .
159                 ENDP
160 SVC_Handler     PROC
161                 EXPORT  SVC_Handler                [WEAK]
162                 B       .
163                 ENDP
164 DebugMon_Handler
165                 PROC
166                 EXPORT  DebugMon_Handler           [WEAK]
167                 B       .
168                 ENDP
169 PendSV_Handler  PROC
170                 EXPORT  PendSV_Handler             [WEAK]
171                 B       .
172                 ENDP
173 SysTick_Handler PROC
174                 EXPORT  SysTick_Handler            [WEAK]
175                 B       .
176                 ENDP
177 Default_Handler PROC
178                 EXPORT  WWDG_IRQHandler            [WEAK]
179                 EXPORT  PVD_IRQHandler             [WEAK]
180                 EXPORT  TAMPER_IRQHandler          [WEAK]
181                 EXPORT  RTC_IRQHandler             [WEAK]
182                 EXPORT  FLASH_IRQHandler           [WEAK]
183                 EXPORT  RCC_IRQHandler             [WEAK]
184                 EXPORT  EXTI0_IRQHandler           [WEAK]
185                 EXPORT  EXTI1_IRQHandler           [WEAK]
186                 EXPORT  EXTI2_IRQHandler           [WEAK]
187                 EXPORT  EXTI3_IRQHandler           [WEAK]
188                 EXPORT  EXTI4_IRQHandler           [WEAK]
189                 EXPORT  DMA1_Channel1_IRQHandler   [WEAK]
190                 EXPORT  DMA1_Channel2_IRQHandler   [WEAK]
191                 EXPORT  DMA1_Channel3_IRQHandler   [WEAK]
192                 EXPORT  DMA1_Channel4_IRQHandler   [WEAK]
193                 EXPORT  DMA1_Channel5_IRQHandler   [WEAK]
194                 EXPORT  DMA1_Channel6_IRQHandler   [WEAK]
195                 EXPORT  DMA1_Channel7_IRQHandler   [WEAK]
196                 EXPORT  ADC1_2_IRQHandler          [WEAK]
197                 EXPORT  USB_HP_CAN1_TX_IRQHandler  [WEAK]
198                 EXPORT  USB_LP_CAN1_RX0_IRQHandler [WEAK]
199                 EXPORT  CAN1_RX1_IRQHandler        [WEAK]
200                 EXPORT  CAN1_SCE_IRQHandler        [WEAK]
201                 EXPORT  EXTI9_5_IRQHandler         [WEAK]
202                 EXPORT  TIM1_BRK_IRQHandler        [WEAK]
203                 EXPORT  TIM1_UP_IRQHandler         [WEAK]
204                 EXPORT  TIM1_TRG_COM_IRQHandler    [WEAK]
205                 EXPORT  TIM1_CC_IRQHandler         [WEAK]
206                 EXPORT  TIM2_IRQHandler            [WEAK]
207                 EXPORT  TIM3_IRQHandler            [WEAK]
208                 EXPORT  TIM4_IRQHandler            [WEAK]
209                 EXPORT  I2C1_EV_IRQHandler         [WEAK]
210                 EXPORT  I2C1_ER_IRQHandler         [WEAK]
211                 EXPORT  I2C2_EV_IRQHandler         [WEAK]
212                 EXPORT  I2C2_ER_IRQHandler         [WEAK]
213                 EXPORT  SPI1_IRQHandler            [WEAK]
214                 EXPORT  SPI2_IRQHandler            [WEAK]
215                 EXPORT  USART1_IRQHandler          [WEAK]
216                 EXPORT  USART2_IRQHandler          [WEAK]
217                 EXPORT  USART3_IRQHandler          [WEAK]
218                 EXPORT  EXTI15_10_IRQHandler       [WEAK]
219                 EXPORT  RTCAlarm_IRQHandler        [WEAK]
220                 EXPORT  USBWakeUp_IRQHandler       [WEAK]
221                 EXPORT  TIM8_BRK_IRQHandler        [WEAK]
222                 EXPORT  TIM8_UP_IRQHandler         [WEAK]
223                 EXPORT  TIM8_TRG_COM_IRQHandler    [WEAK]
224                 EXPORT  TIM8_CC_IRQHandler         [WEAK]
225                 EXPORT  ADC3_IRQHandler            [WEAK]
226                 EXPORT  FSMC_IRQHandler            [WEAK]
227                 EXPORT  SDIO_IRQHandler            [WEAK]
228                 EXPORT  TIM5_IRQHandler            [WEAK]
229                 EXPORT  SPI3_IRQHandler            [WEAK]
230                 EXPORT  UART4_IRQHandler           [WEAK]
231                 EXPORT  UART5_IRQHandler           [WEAK]
232                 EXPORT  TIM6_IRQHandler            [WEAK]
233                 EXPORT  TIM7_IRQHandler            [WEAK]
234                 EXPORT  DMA2_Channel1_IRQHandler   [WEAK]
235                 EXPORT  DMA2_Channel2_IRQHandler   [WEAK]
236                 EXPORT  DMA2_Channel3_IRQHandler   [WEAK]
237                 EXPORT  DMA2_Channel4_5_IRQHandler [WEAK]
238 WWDG_IRQHandler
239 PVD_IRQHandler
240 TAMPER_IRQHandler
241 RTC_IRQHandler
242 FLASH_IRQHandler
243 RCC_IRQHandler
244 EXTI0_IRQHandler
245 EXTI1_IRQHandler
246 EXTI2_IRQHandler
247 EXTI3_IRQHandler
248 EXTI4_IRQHandler
249 DMA1_Channel1_IRQHandler
250 DMA1_Channel2_IRQHandler
251 DMA1_Channel3_IRQHandler
252 DMA1_Channel4_IRQHandler
253 DMA1_Channel5_IRQHandler
254 DMA1_Channel6_IRQHandler
255 DMA1_Channel7_IRQHandler
256 ADC1_2_IRQHandler
257 USB_HP_CAN1_TX_IRQHandler
258 USB_LP_CAN1_RX0_IRQHandler
259 CAN1_RX1_IRQHandler
260 CAN1_SCE_IRQHandler
261 EXTI9_5_IRQHandler
262 TIM1_BRK_IRQHandler
263 TIM1_UP_IRQHandler
264 TIM1_TRG_COM_IRQHandler
265 TIM1_CC_IRQHandler
266 TIM2_IRQHandler
267 TIM3_IRQHandler
268 TIM4_IRQHandler
269 I2C1_EV_IRQHandler
270 I2C1_ER_IRQHandler
271 I2C2_EV_IRQHandler
272 I2C2_ER_IRQHandler
273 SPI1_IRQHandler
274 SPI2_IRQHandler
275 USART1_IRQHandler
276 USART2_IRQHandler
277 USART3_IRQHandler
278 EXTI15_10_IRQHandler
279 RTCAlarm_IRQHandler
280 USBWakeUp_IRQHandler
281 TIM8_BRK_IRQHandler
282 TIM8_UP_IRQHandler
283 TIM8_TRG_COM_IRQHandler
284 TIM8_CC_IRQHandler
285 ADC3_IRQHandler
286 FSMC_IRQHandler
287 SDIO_IRQHandler
288 TIM5_IRQHandler
289 SPI3_IRQHandler
290 UART4_IRQHandler
291 UART5_IRQHandler
292 TIM6_IRQHandler
293 TIM7_IRQHandler
294 DMA2_Channel1_IRQHandler
295 DMA2_Channel2_IRQHandler
296 DMA2_Channel3_IRQHandler
297 DMA2_Channel4_5_IRQHandler
298                 B       .
299                 ENDP
300                 ALIGN ;填充字节使地址对齐
301 ;*******************************************************************************
302 ; User Stack and Heap initialization
303 ;*******************************************************************************
304 ;堆和栈的初始化
305                  IF      :DEF:__MICROLIB ;“DEF”的用法——:DEF:X 就是说X定义了则为真，否则为假
306                        ;如果定义了MICORLIB,
307                  EXPORT  __initial_sp  ;则将栈顶地址，
308                  EXPORT  __heap_base  ;堆起始地址赋予全局属性，
309                  EXPORT  __heap_limit  ;堆末端界限地址赋予全局属性,使外部程序可调用
310                 
311                  ELSE  ;如果没定义__MICROLIB,则使用默认的C运行时库
312                 
313                  IMPORT  __use_two_region_memory  ;;通知编译器要使用的标号在其他文件__use_two_region_memory    
314                  EXPORT  __user_initial_stackheap ;声明全局标号__user_initial_stackheap，这样外程序也可调用此标号
315              ;则进行堆栈和堆的赋值，在__main函数执行过程中调用
316
317     ;如果使用默认的C库,程序启动过程中就不会执行该标号下的代码
318 __user_initial_stackheap     ;标号__user_initial_stackheap，表示用户堆栈初始化程序入口
319         ;//则进行堆栈和堆的赋值，在__main函数执行过程中调用。
320                  LDR     R0, =  Heap_Mem     ;保存堆始地址
321                  LDR     R1, =(Stack_Mem + Stack_Size) ;保存栈的大小
322                  LDR     R2, = (Heap_Mem +  Heap_Size)  ;保存堆的大小
323                  LDR     R3, = Stack_Mem    ;保存栈顶指针
324                  BX      LR
325                  ALIGN  ;填充字节使地址对齐
326
327                  ENDIF
328      
329                  END