对stm32f373XX的startup.s的文件的分析

;******************** (C) COPYRIGHT 2012 STMicroelectronics ********************
;* File Name : startup_stm32f37x.s
;* Author : MCD Application Team
;* Version : V1.0.0
;* Date : 20-September-2012
;* Description : STM32F37x devices vector table for MDK-ARM toolchain.
;* This module performs:
;* - Set the initial SP /*设置初始的栈*/
;* - Set the initial PC == Reset_Handler /*设置初始的指针指向Reset_Handler*/
;* - Set the vector table entries with the exceptions ISR address /*设置向量表入口*/
;* - Branches to __main in the C library (which eventually /*跳转到c的函数入口*/
;* calls main()).
;* After Reset the CortexM4 processor is in Thread mode,
;* priority is Privileged, and the Stack is set to Main.
;* <<< Use Configuration Wizard in Context Menu >>>
;*******************************************************************************
; @attention
;
; Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
; You may not use this file except in compliance with the License.
; You may obtain a copy of the License at:
;
; http://www.st.com/software_license_agreement_liberty_v2
;
; Unless required by applicable law or agreed to in writing, software
; distributed under the License is distributed on an "AS IS" BASIS,
; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
; See the License for the specific language governing permissions and
; limitations under the License.
;
;*******************************************************************************
;
; Amount of memory (in bytes) allocated for Stack
; Tailor this value to your application needs
; <h> Stack Configuration /*栈的设置，栈是用来供应用程序自动执行的，里面包含的是程序运行的状态，以及跳转等等*/
; <o> Stack Size (in Bytes) <0x0-0xFFFFFFFF:8>
; </h>

Stack_Size EQU 0x00000400

AREA STACK, NOINIT, READWRITE, ALIGN=3 /*AREA这个伪指令表示下面将开始定义一个代码段或者数据段。STACK：表示这个段的名字，可以任意命名。
NOINIUT：表示此数据段不需要填入初始数据，READWEITE：表示此段可读可写，ALLGN=3，表示首地址按照2
的3次方对齐，也就是按照8字节对齐。
*/
Stack_Mem SPACE Stack_Size /*SPACE这行指令告诉汇编器给STACK段分配0x000008000字节的连续空间*/
__initial_sp /*_initial_sp这只是一个标号，并没有实质的含义*/

; <h> Heap Configuration /*堆的设置，堆的空间是用来提供给用户使用的，可以用户来分配内存呀啥的*/
; <o> Heap Size (in Bytes) <0x0-0xFFFFFFFF:8>
; </h>

Heap_Size EQU 0x00000200

AREA HEAP, NOINIT, READWRITE, ALIGN=3
__heap_base /*_heap_base为堆的起始地址，_heap_limit为堆的结束地址，因为堆由的地址向高地址增长*/
Heap_Mem SPACE Heap_Size
__heap_limit

PRESERVE8 /*指定当前文件保持堆栈8字节对齐*/
THUMB /*THUMB表示后面的指令是THUMB指令集，CM4采用的是THUMB-2指令集*/

; Vector Table Mapped to Address 0 at Reset
AREA RESET, DATA, READONLY /*AREA定义一块代码段，只读，段名字是RESET。*/
EXPORT __Vectors /*表示可被外部引用*/
EXPORT __Vectors_End
EXPORT __Vectors_Size

__Vectors DCD __initial_sp ; Top of Stack /*建立中断向量表，中断向量表在代码段的最前面，DCD表示分配1个4字节的空间*/
DCD Reset_Handler ; Reset Handler /*中断向量表存放的实际上是中断服务程序的入口地址，当异常发生时，cpu的中断系统会将相应的入口地址赋值给pc寄存器，之后开始执行中断服务程序*/
DCD NMI_Handler ; NMI Handler
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 ; Reserved
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 detection
DCD TAMPER_STAMP_IRQHandler ; Tamper and TimeStamps through the EXTI line
DCD RTC_WKUP_IRQHandler ; RTC Wakeup through the EXTI line
DCD FLASH_IRQHandler ; FLASH
DCD RCC_IRQHandler ; RCC
DCD EXTI0_IRQHandler ; EXTI Line0
DCD EXTI1_IRQHandler ; EXTI Line1
DCD EXTI2_TS_IRQHandler ; EXTI Line2 and Touch Sense
DCD EXTI3_IRQHandler ; EXTI Line3
DCD EXTI4_IRQHandler ; EXTI Line4
DCD DMA1_Channel1_IRQHandler ; DMA1 Channel 1
DCD DMA1_Channel2_IRQHandler ; DMA1 Channel 2
DCD DMA1_Channel3_IRQHandler ; DMA1 Channel 3
DCD DMA1_Channel4_IRQHandler ; DMA1 Channel 4
DCD DMA1_Channel5_IRQHandler ; DMA1 Channel 5
DCD DMA1_Channel6_IRQHandler ; DMA1 Channel 6
DCD DMA1_Channel7_IRQHandler ; DMA1 Channel 7
DCD ADC1_IRQHandler ; ADC1
DCD CAN1_TX_IRQHandler ; CAN1 TX
DCD CAN1_RX0_IRQHandler ; CAN1 RX0
DCD CAN1_RX1_IRQHandler ; CAN1 RX1
DCD CAN1_SCE_IRQHandler ; CAN1 SCE
DCD EXTI9_5_IRQHandler ; External Line[9:5]s
DCD TIM15_IRQHandler ; TIM15
DCD TIM16_IRQHandler ; TIM16
DCD TIM17_IRQHandler ; TIM17
DCD TIM18_DAC2_IRQHandler ; TIM18 and DAC2
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 ; External Line[15:10]s
DCD RTC_Alarm_IRQHandler ; RTC Alarm (A and B) through EXTI Line
DCD CEC_IRQHandler ; CEC
DCD TIM12_IRQHandler ; TIM12
DCD TIM13_IRQHandler ; TIM13
DCD TIM14_IRQHandler ; TIM14
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD TIM5_IRQHandler ; TIM5
DCD SPI3_IRQHandler ; SPI3
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD TIM6_DAC1_IRQHandler ; TIM6 and DAC1 Channel1 & channel2
DCD TIM7_IRQHandler ; TIM7
DCD DMA2_Channel1_IRQHandler ; DMA2 Channel 1
DCD DMA2_Channel2_IRQHandler ; DMA2 Channel 2
DCD DMA2_Channel3_IRQHandler ; DMA2 Channel 3
DCD DMA2_Channel4_IRQHandler ; DMA2 Channel 4
DCD DMA2_Channel5_IRQHandler ; DMA2 Channel 5
DCD SDADC1_IRQHandler ; SDADC1
DCD SDADC2_IRQHandler ; SDADC2
DCD SDADC3_IRQHandler ; SDADC3
DCD COMP_IRQHandler ; COMP
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD USB_HP_IRQHandler ; USB High Priority
DCD USB_LP_IRQHandler ; USB Low Priority
DCD USBWakeUp_IRQHandler ; USB Wakeup
DCD 0 ; Reserved
DCD TIM19_IRQHandler ; TIM19
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD FPU_IRQHandler ; FPU
__Vectors_End

__Vectors_Size EQU __Vectors_End - __Vectors

AREA |.text|, CODE /*AREA定义一块代码段，只读，段名字时.test*/

; Reset handler
Reset_Handler PROC /*利用 PROC和ENDP这一对伪指令把程序段分为若干个过程，使程序的结构更加清晰*/
EXPORT Reset_Handler [WEAK]/*WEAK声明其它的同名标号优先于该标号被引用，就是说如果外面声明了的话会调用外面的。这个声明很重要，它*/
IMPORT SystemInit /*让我们可以在c为念中任意地方放置中断服务程序，只要保证c函数的名字和向量表中的名字一致即可*/
IMPORT __main /**IMPORT：伪指令用于通知编译器要使用的标号在其它的源文件中的定义。但要在当前源文件中引用，而且无论当前源文件是否引用该*/
/*标号，该标号均会被加入到当前源文件的符号表中*/
LDR R0, =SystemInit
BLX R0
LDR R0, =__main /*_main标号表示c/c++标准实时库函数里的一个初始化子程序_main的入口地址。该程序的一个主要作用是初始化堆栈，配置系统环境，在函数的最后调用用户编写的main函数，进入c的世界*/
BX R0
ENDP

; Dummy Exception Handlers (infinite loops which can be modified)

NMI_Handler PROC
EXPORT NMI_Handler [WEAK]
B .
ENDP
HardFault_Handler\
PROC
EXPORT HardFault_Handler [WEAK]
B .
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 .
ENDP
SysTick_Handler PROC
EXPORT SysTick_Handler [WEAK]
B .
ENDP

Default_Handler PROC

EXPORT WWDG_IRQHandler [WEAK] /*此处为中断服务程序，如果在c中定义了中断服务程序，就会使用c中的中断服务程序*/
EXPORT PVD_IRQHandler [WEAK]
EXPORT TAMPER_STAMP_IRQHandler [WEAK]
EXPORT RTC_WKUP_IRQHandler [WEAK]
EXPORT FLASH_IRQHandler [WEAK]
EXPORT RCC_IRQHandler [WEAK]
EXPORT EXTI0_IRQHandler [WEAK]
EXPORT EXTI1_IRQHandler [WEAK]
EXPORT EXTI2_TS_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_IRQHandler [WEAK]
EXPORT CAN1_TX_IRQHandler [WEAK]
EXPORT CAN1_RX0_IRQHandler [WEAK]
EXPORT CAN1_RX1_IRQHandler [WEAK]
EXPORT CAN1_SCE_IRQHandler [WEAK]
EXPORT EXTI9_5_IRQHandler [WEAK]
EXPORT TIM15_IRQHandler [WEAK]
EXPORT TIM16_IRQHandler [WEAK]
EXPORT TIM17_IRQHandler [WEAK]
EXPORT TIM18_DAC2_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 RTC_Alarm_IRQHandler [WEAK]
EXPORT CEC_IRQHandler [WEAK]
EXPORT TIM12_IRQHandler [WEAK]
EXPORT TIM13_IRQHandler [WEAK]
EXPORT TIM14_IRQHandler [WEAK]
EXPORT TIM5_IRQHandler [WEAK]
EXPORT SPI3_IRQHandler [WEAK]
EXPORT TIM6_DAC1_IRQHandler [WEAK]
EXPORT TIM7_IRQHandler [WEAK]
EXPORT DMA2_Channel1_IRQHandler [WEAK]
EXPORT DMA2_Channel2_IRQHandler [WEAK]
EXPORT DMA2_Channel3_IRQHandler [WEAK]
EXPORT DMA2_Channel4_IRQHandler [WEAK]
EXPORT DMA2_Channel5_IRQHandler [WEAK]
EXPORT SDADC1_IRQHandler [WEAK]
EXPORT SDADC2_IRQHandler [WEAK]
EXPORT SDADC3_IRQHandler [WEAK]
EXPORT COMP_IRQHandler [WEAK]
EXPORT USB_HP_IRQHandler [WEAK]
EXPORT USB_LP_IRQHandler [WEAK]
EXPORT USBWakeUp_IRQHandler [WEAK]
EXPORT TIM19_IRQHandler [WEAK]
EXPORT FPU_IRQHandler [WEAK]

WWDG_IRQHandler
PVD_IRQHandler
TAMPER_STAMP_IRQHandler
RTC_WKUP_IRQHandler
FLASH_IRQHandler
RCC_IRQHandler
EXTI0_IRQHandler
EXTI1_IRQHandler
EXTI2_TS_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_IRQHandler
CAN1_TX_IRQHandler
CAN1_RX0_IRQHandler
CAN1_RX1_IRQHandler
CAN1_SCE_IRQHandler
EXTI9_5_IRQHandler
TIM15_IRQHandler
TIM16_IRQHandler
TIM17_IRQHandler
TIM18_DAC2_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
RTC_Alarm_IRQHandler
CEC_IRQHandler
TIM12_IRQHandler
TIM13_IRQHandler
TIM14_IRQHandler
TIM5_IRQHandler
SPI3_IRQHandler
TIM6_DAC1_IRQHandler
TIM7_IRQHandler
DMA2_Channel1_IRQHandler
DMA2_Channel2_IRQHandler
DMA2_Channel3_IRQHandler
DMA2_Channel4_IRQHandler
DMA2_Channel5_IRQHandler
SDADC1_IRQHandler
SDADC2_IRQHandler
SDADC3_IRQHandler
COMP_IRQHandler
USB_HP_IRQHandler
USB_LP_IRQHandler
USBWakeUp_IRQHandler
TIM19_IRQHandler
FPU_IRQHandler

B . /*B指的是死循环*/

ENDP

ALIGN

;*******************************************************************************
; User Stack and Heap initialization
;*******************************************************************************
IF :DEF:__MICROLIB /*使用IF。。。。ELSE。。。如果定义了MICROLIB，那么程序只会执行ELSE的分支。*/
/*_user_initial_stackheap将由_main函数进行调用*/
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

ENDIF

END

;************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE*****
/*主闪存存储器：芯片内部的flash,即256K字节，从用户闪存启动，这是正常的工作模式*/
/*系统存储器：应该类似于(18k字节)，将程序写入到一块特定的区域，一般由厂家之直接写入，不能被随意更改或擦除。*/
/*内置SRAM：64K字节，由于SRAM掉电丢失，不能保存程序，一般只用于程序的调试*/

总结：对于此文件的分析可得知，首先系统启动时先设好堆和栈，然后时中断向量表的设置，之后是系统的初始化（时钟和关闭中断等等），然后跳转到_main（）函数中，在这里要注意_main()函数并不是我们编写的main()函数，而是c/c++运行时库的一个函数，嵌入式系统在进入应用程序之前必须由一个初始化的过程，使用_main标号引导系统时必须将应用程序的入口定义为main().

在初始化的过程中，_main函数的作用主要是：

完成对映像文件的初始化操作

起始时对于加载地址和执行地址不同的映像我呢见，_main函数会把加载地址的代码和数据复制到执行地址中，并且对被连接器指定为需要初始化为0的段，并且对被链接器指定为初始化为0的段，进行清零操作。分析到这里，感觉和写bootloader的程序好像。