STM32 arm匯編(thumb-2指令集)啟動(dòng)代碼分析
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;//
;//
Stack_Size EQU 0x00000200 ;//定義堆棧大小
AREA STACK, NOINIT, READWRITE, ALIGN=3 ;//定義一個(gè)數(shù)據(jù)段 按8字節(jié)對(duì)齊 ;AREA 偽指令用于定義一個(gè)代碼段或數(shù)據(jù)段 NOINIT：指定此數(shù)據(jù)段僅僅保留了內(nèi)存單元，而沒(méi)有將各初始值寫(xiě)入內(nèi)存單元，或者將各個(gè)內(nèi)存單元值初始化為0
Stack_Mem SPACE Stack_Size ;//保留Stack_Size大小的堆?？臻g 分 配連續(xù) Stack_Size 字節(jié)的存儲(chǔ)單元并初始化為 0
__initial_sp ;//標(biāo)號(hào)，代表堆棧頂部地址，后面有用
;//
;//
;//
Heap_Size EQU 0x00000020 ;//定義堆空間大小
AREA HEAP, NOINIT, READWRITE, ALIGN=3 ;//定義一個(gè)數(shù)據(jù)段，8字節(jié)對(duì)齊
__heap_base
Heap_Mem SPACE Heap_Size ;//保留Heap_Size的堆空間
__heap_limit ;//標(biāo)號(hào)，代表堆末尾地址，后面有用
PRESERVE8 ;//指示編譯器8字節(jié)對(duì)齊
THUMB ;//指示編譯器為T(mén)HUMB指令
; Vector Table Mapped to Address 0 at Reset
AREA RESET, DATA, READONLY ;//定義只讀數(shù)據(jù)段，其實(shí)放在CODE區(qū)，位于0地址
EXTERN NMIException
EXTERN HardFaultException
EXTERN MemManageException
EXTERN BusFaultException
EXTERN UsageFaultException
EXTERN SVCHandler
EXTERN DebugMonitor
EXTERN PendSVC
EXTERN SysTickHandler ;//聲明這些符號(hào)在外部定義，同C
;//在××it.c中實(shí)現(xiàn)這些函數(shù) ，中斷就能自動(dòng)調(diào)用了
EXPORT __Vectors
EXPORT __initial_sp ;EXPORT：在程序中聲明一個(gè)全局的標(biāo)號(hào)__Vectors，該標(biāo)號(hào)可在其他的文件中引用；IMPORT：偽指令用于通知編譯器要使用的標(biāo)號(hào)在其他的源文件中定義， ;但要在當(dāng)前源文件中引用，而且無(wú)論當(dāng)前源文件是否引用該標(biāo)號(hào)，該標(biāo)號(hào)均會(huì)被加入到當(dāng)前源文件的符號(hào)表中
__Vectors DCD __initial_sp ; Top of Stack //Cotex-M 要求此處為堆棧頂部地址
DCD Reset_Handler ; Reset Handler
DCD NMIException ; NMI Handler
DCD HardFaultException ; Hard Fault Handler
DCD MemManageException ; MPU Fault Handler
DCD BusFaultException ; Bus Fault Handler
DCD UsageFaultException ; Usage Fault Handler
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD SVCHandler ; SVCall Handler
DCD DebugMonitor ; Debug Monitor Handler
DCD 0 ; Reserved
DCD PendSVC ; PendSV Handler
DCD SysTickHandler ; SysTick Handler //一大堆的異常處理函數(shù)地址
; External Interrupts
EXTERN WWDG_IRQHandler
EXTERN PVD_IRQHandler
EXTERN TAMPER_IRQHandler
EXTERN RTC_IRQHandler
EXTERN FLASH_IRQHandler
EXTERN RCC_IRQHandler
EXTERN EXTI0_IRQHandler
EXTERN EXTI1_IRQHandler
EXTERN EXTI2_IRQHandler
EXTERN EXTI3_IRQHandler
EXTERN EXTI4_IRQHandler
EXTERN DMAChannel1_IRQHandler
EXTERN DMAChannel2_IRQHandler
EXTERN DMAChannel3_IRQHandler
EXTERN DMAChannel4_IRQHandler
EXTERN DMAChannel5_IRQHandler
EXTERN DMAChannel6_IRQHandler
EXTERN DMAChannel7_IRQHandler
EXTERN ADC_IRQHandler
EXTERN USB_HP_CAN_TX_IRQHandler
EXTERN USB_LP_CAN_RX0_IRQHandler
EXTERN CAN_RX1_IRQHandler
EXTERN CAN_SCE_IRQHandler
EXTERN EXTI9_5_IRQHandler
EXTERN TIM1_BRK_IRQHandler
EXTERN TIM1_UP_IRQHandler
EXTERN TIM1_TRG_COM_IRQHandler
EXTERN TIM1_CC_IRQHandler
EXTERN TIM2_IRQHandler
EXTERN TIM3_IRQHandler
EXTERN TIM4_IRQHandler
EXTERN I2C1_EV_IRQHandler
EXTERN I2C1_ER_IRQHandler
EXTERN I2C2_EV_IRQHandler
EXTERN I2C2_ER_IRQHandler
EXTERN SPI1_IRQHandler
EXTERN SPI2_IRQHandler
EXTERN USART1_IRQHandler
EXTERN USART2_IRQHandler
EXTERN USART3_IRQHandler
EXTERN EXTI15_10_IRQHandler
EXTERN RTCAlarm_IRQHandler
EXTERN USBWakeUp_IRQHandler ;//同上，
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
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 ;//同上
AREA |.text|, CODE, READONLY ;//定義代碼段
; Reset Handler
Reset_Handler PROC ;過(guò)程的開(kāi)始
;//Rset_Handler的實(shí)現(xiàn) 利用PROC、ENDP這一對(duì)偽指令把程序段分為若干個(gè)過(guò)程，使程序的結(jié)構(gòu)加清晰
EXPORT Reset_Handler [WEAK] ;//在外部沒(méi)有定義該符號(hào)時(shí)導(dǎo)出該符號(hào)，見(jiàn)HELP中[WEAK]
IMPORT __main ;//導(dǎo)入符號(hào),__main為 運(yùn)行時(shí)庫(kù)提供的函數(shù)；完成堆棧，堆的初始話
LDR R0, =__main ;//等工作，會(huì)調(diào)用下面定義的__user_initial_stackheap；
BX R0 ;//跳到__main，進(jìn)入C的世界
ENDP ;過(guò)程的結(jié)束
ALIGN
; User Initial Stack & Heap
IF :DEF:__MICROLIB ;//如果使用micro lib,micro lib 描述見(jiàn)armlib.chm
EXPORT __heap_base
EXPORT __heap_limit ;//只導(dǎo)出幾個(gè)定義
ELSE ;//如果使用默認(rèn)C運(yùn)行時(shí)庫(kù)
IMPORT __use_two_region_memory
EXPORT __user_initial_stackheap
__user_initial_stackheap ;//則進(jìn)行堆棧和堆的賦值，在__main函數(shù)執(zhí)行過(guò)程中調(diào)用。
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 ;//OK ，完了
http://blog.csdn.net/chehlcy/archive/2010/01/09/5164472.aspx
http://files.ourdev.cn/bbs_upload134190/files_11/ourdev_495775.txt
======================================================================
Reset_Handler PROC
EXPORT Reset_Handler [WEAK]
IMPORT __main
LDR R0, =__main
BX R0
ENDP
這段代碼什么意思。
有2個(gè)地方不理解
一：PROC ENDP
二： [WEAK] 什么意思
-------------------------------------------------------------------------------
一：PROC為子程序開(kāi)始，ENDP為子程序結(jié)束
二：[weak]的意思就是弱。
怎么弱呢？如果你在其他地方寫(xiě)一個(gè)同名函數(shù)，比如Reset_handler, 你寫(xiě)的這個(gè)函數(shù)就可以取代它這個(gè)函數(shù)了。
語(yǔ)法格式：
EXPORT 標(biāo)號(hào) {[WEAK]}
EXPORT 偽指令用于在程序中聲明一個(gè)全局的標(biāo)號(hào)，該標(biāo)號(hào)可在其他的文件中引用。 EXPORT可用 GLOBAL 代替。標(biāo)號(hào)在程序中區(qū)分大小寫(xiě)， [WEAK] 選項(xiàng)聲明其他的同名標(biāo)號(hào)優(yōu)先于該標(biāo)號(hào)被引用。
使用示例：
AREA Init ， CO
EXPORT Stest ；聲明一個(gè)可全局引用的標(biāo)號(hào)Stest……
END
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