KEA128单片机启动代码分析

;/*****************************************************************************
; * @file: startup_SKEAZ1284.s
; * @purpose: CMSIS Cortex-M0plus Core Device Startup File for the
; * SKEAZ1284
; * @version: 1.0
; * @date: 2013-10-30
; *
; * Copyright: 1997 - 2013 Freescale Semiconductor, Inc. All Rights Reserved.
;*
; *------- <<< Use Configuration Wizard in Context Menu >>> ------------------
; *
; *****************************************************************************/

; <h> Stack Configuration
; <o> Stack Size (in Bytes) <0x0-0xFFFFFFFF:8>
; </h>

堆和栈初始化

Stack_Size EQU 0x00000100                                         分配栈大小

AREA STACK, NOINIT, READWRITE, ALIGN=3　　　　　　设置栈区属性：初始化为0，8字节对齐
Stack_Mem SPACE Stack_Size                                
__initial_sp                                                                  栈空间顶地址，汇编代码地址标号

; <h> Heap Configuration
; <o> Heap Size (in Bytes) <0x0-0xFFFFFFFF:8>
; </h>

Heap_Size EQU 0x00000000

AREA HEAP, NOINIT, READWRITE, ALIGN=3
__heap_base                                                                堆空间起始地址
Heap_Mem SPACE Heap_Size
__heap_limit                                                                堆空间结束地址

PRESERVE8                                                                  指令指定当前文件保持堆栈八字节对齐
THUMB　　　　　　　　　　　　　　　　　　　　　　　　　　告诉汇编器下面是32位的Thumb指令，如果需要汇编器将插入位以保证对齐

; Vector Table Mapped to Address 0 at Reset

设置中断向量表

AREA RESET, DATA, READONLY                 　　　　　　　定义一块数据段，只可读，段名字是RESET
EXPORT __Vectors                             　　　　　　　　　  EXPORT：在程序中声明一个全局的标号，该标号可在其他的文件中引用
EXPORT __Vectors_End
EXPORT __Vectors_Size

__Vectors DCD __initial_sp ; Top of Stack   　　　　　　　第一个表项是栈顶地址，该地址中存储__initial_sp所表示的地址值
DCD Reset_Handler ; Reset Handler　　　　　　　　　　　 第二个表项是复位中断服务入口地址
DCD NMI_Handler ; NMI Handler
DCD HardFault_Handler ; Hard Fault Handler
DCD 0 ; Reserved　　　　　　　　　　　　　　　　　　　　 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 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD SVC_Handler ; SVCall Handler　　　　　　　　　　　  SVCall Handler 执行系统服务调用指令（SVC）引发的异常
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD PendSV_Handler ; PendSV Handler
DCD SysTick_Handler ; SysTick Handler

; External Interrupts
DCD Reserved16_IRQHandler ; Reserved interrupt 16
DCD Reserved17_IRQHandler ; Reserved interrupt 17
DCD Reserved18_IRQHandler ; Reserved interrupt 18
DCD Reserved19_IRQHandler ; Reserved interrupt 19
DCD Reserved20_IRQHandler ; Reserved interrupt 20
DCD FTMRE_IRQHandler ; FTMRE command complete/read collision interrupt
DCD LVD_LVW_IRQHandler ; Low Voltage Detect, Low Voltage Warning
DCD IRQ_IRQHandler ; External interrupt
DCD I2C0_IRQHandler ; I2C0 interrupt
DCD I2C1_IRQHandler ; I2C1 interrupt
DCD SPI0_IRQHandler ; SPI0 interrupt
DCD SPI1_IRQHandler ; SPI1 interrupt
DCD UART0_IRQHandler ; UART0 status/error interrupt
DCD UART1_IRQHandler ; UART1 status/error interrupt
DCD UART2_IRQHandler ; UART2 status/error interrupt
DCD ADC0_IRQHandler ; ADC0 interrupt
DCD ACMP0_IRQHandler ; ACMP0 interrupt
DCD FTM0_IRQHandler ; FTM0 Single interrupt vector for all sources
DCD FTM1_IRQHandler ; FTM1 Single interrupt vector for all sources
DCD FTM2_IRQHandler ; FTM2 Single interrupt vector for all sources
DCD RTC_IRQHandler ; RTC overflow
DCD ACMP1_IRQHandler ; ACMP1 interrupt
DCD PIT_CH0_IRQHandler ; PIT CH0 overflow
DCD PIT_CH1_IRQHandler ; PIT CH1 overflow
DCD KBI0_IRQHandler ; Keyboard interrupt 0
DCD KBI1_IRQHandler ; Keyboard interrupt 1
DCD Reserved42_IRQHandler ; Reserved interrupt 42
DCD ICS_IRQHandler ; ICS interrupt
DCD Watchdog_IRQHandler ; WDOG Interrupt
DCD PWT_IRQHandler ; Pulse Width Timer Interrupt
DCD MSCAN_RX_IRQHandler ; MSCAN Rx Interrupt
DCD MSCAN_TX_IRQHandler ; MSCAN Tx, Err and Wake-up interrupt
__Vectors_End　　　　　　　　　　　　　　　　　　　　　　　

__Vectors_Size EQU __Vectors_End - __Vectors                    得到向量表的地址大小

; <h> Flash Configuration
; <i> 16-byte flash configuration field that stores default protection settings (loaded on reset)
; <i> and security information that allows the MCU to restrict acces to the FTFL module.
; <h> Backdoor Comparison Key
; <o0> Backdoor Key 0 <0x0-0xFF:2>
; <o1> Backdoor Key 1 <0x0-0xFF:2>
; <o2> Backdoor Key 2 <0x0-0xFF:2>
; <o3> Backdoor Key 3 <0x0-0xFF:2>
; <o4> Backdoor Key 4 <0x0-0xFF:2>
; <o5> Backdoor Key 5 <0x0-0xFF:2>
; <o6> Backdoor Key 6 <0x0-0xFF:2>
; <o7> Backdoor Key 7 <0x0-0xFF:2>
BackDoorK0 EQU 0xFF
BackDoorK1 EQU 0xFF
BackDoorK2 EQU 0xFF
BackDoorK3 EQU 0xFF
BackDoorK4 EQU 0xFF
BackDoorK5 EQU 0xFF
BackDoorK6 EQU 0xFF
BackDoorK7 EQU 0xFF
; </h>
; <h> EEPROM Protection Register (EEPROT)
; <i> The DFPROT register defines which D-Flash sectors are protected against program and erase operations.
; <o.7> DPOPEN
; <0=> Enables EEPROM memory protection
; <1=> Disables EEPROM memory protection
; <o.0..2> DPS
; <0=> Flash address range: 0x00_0000 - 0x00_001F; protected size: 32 bytes
; <1=> Flash address range: 0x00_0000 - 0x00_003F; protected size: 64 bytes
; <2=> Flash address range: 0x00_0000 - 0x00_005F; protected size: 96 bytes
; <3=> Flash address range: 0x00_0000 - 0x00_007F; protected size: 128 bytes
; <4=> Flash address range: 0x00_0000 - 0x00_009F; protected size: 160 bytes
; <5=> Flash address range: 0x00_0000 - 0x00_00BF; protected size: 192 bytes
; <6=> Flash address range: 0x00_0000 - 0x00_00DF; protected size: 224 bytes
; <7=> Flash address range: 0x00_0000 - 0x00_00FF; protected size: 256 bytes
EEPROT EQU 0xFF
; </h>
; <h> FPROT
; <i> P-Flash Protection Register
; <o.7> FPOPEN
; <0=> FPHDIS and FPLDIS bits define unprotected address ranges as specified by the corresponding FPHS and FPLS bits FPROT1.1
; <1=> FPHDIS and FPLDIS bits enable protection for the address range specified by the corresponding FPHS and FPLS bits
; <o.5> FPHDIS
; <0=> Protection/Unprotection enabled
; <1=> Protection/Unprotection disabled
; <o.3..4> FPHS
; <0=> Address range: 0x00_7C00-0x00_7FFF; protected size: 1 KB
; <1=> Address range: 0x00_7800-0x00_7FFF; protected size: 2 KB
; <2=> Address range: 0x00_7000-0x00_7FFF; protected size: 4 KB
; <3=> Address range: 0x00_6000-0x00_7FFF; protected size: 8 KB
; <o.5> FPLDIS
; <0=> Protection/Unprotection enabled
; <1=> Protection/Unprotection disabled
; <o.3..4> FPLS
; <0=> Address range: 0x00_0000-0x00_07FF; protected size: 2 KB
; <1=> Address range: 0x00_0000-0x00_0FFF; protected size: 4 KB
; <2=> Address range: 0x00_0000-0x00_1FFF; protected size: 8 KB
; <3=> Address range: 0x00_0000-0x00_3FFF; protected size: 16 KB
FPROT EQU 0xFF
; </h>
; </h>
; <h> Flash security byte (FSEC)
; <i> WARNING: If SEC field is configured as "MCU security status is secure" and MEEN field is configured as "Mass erase is disabled",
; <i> MCU's security status cannot be set back to unsecure state since Mass erase via the debugger is blocked !!!
; <o.0..1> SEC
; <2=> MCU security status is unsecure
; <3=> MCU security status is secure
; <i> Flash Security
; <i> This bits define the security state of the MCU.
; <o.6..7> KEYEN
; <2=> Backdoor key access enabled
; <3=> Backdoor key access disabled
; <i> Backdoor key Security Enable
; <i> These bits enable and disable backdoor key access to the FTFL module.
FSEC EQU 0xFE
; </h>
; <h> Flash Option Register (FOPT)
FOPT EQU 0xFE
; </h>

IF :LNOT::DEF:RAM_TARGET　　　　　　　　　　　　　　　　　　　　　　判断是否定义了RAM_TARGET
AREA |.ARM.__at_0x400|, CODE, READONLY
DCB BackDoorK0, BackDoorK1, BackDoorK2, BackDoorK3
DCB BackDoorK4, BackDoorK5, BackDoorK6, BackDoorK7
DCB 0xFF, 0xFF, 0xFF, 0xFF
DCB 0xFF, FPROT, FSEC, FOPT
ENDIF

AREA |.text|, CODE, READONLY　　　　　　　　　　定义一个代码段，可读，段名字是.text  段名若以数字开头，则该段名需用"|"括起来　　　　　　　　　　　　　　　

;init_data_bss
; User defined function for data and bs memory segment initialization.
; Weak definition to be replaced by user code.

init_data_bss PROC                                             PROC表示汇编函数的开始，初始化bss段
EXPORT init_data_bss [WEAK]　　　　　　　　　　 将函数声明为外部，外部同名函数可覆盖。灵活使用ARM汇编的WEAK关键字

BX R14           　　　　　　　　　　　　　　　　　　 R14为lr寄存器

　　　　　　　　　　　　　　　　　　　　　　　　　　BX Rm 和 BLX Rm 可从 Rm 的位 [0] 推算出目标状态：

　　　　　　　　　　　　　　　　　　　　　　　　　　如果 Rm 的位 [0] 为 0，则处理器的状态会更改为（或保持在）ARM 状态

　　　　　　　　　　　　　　　　　　　　　　　　　　如果 Rm 的位 [0] 为 1，则处理器的状态会更改为（或保持在）Thumb 状态。

ENDP

; Reset Handler

Reset_Handler PROC　　　　　　　　　　　　　　　  复位函数
EXPORT Reset_Handler [WEAK]
IMPORT SystemInit
IMPORT __main
LDR R0, =SystemInit
BLX R0
LDR R0, =init_data_bss
BLX R0
LDR R0, =__main
BX R0
ENDP

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

NMI_Handler PROC                                              定义中断函数入口
EXPORT NMI_Handler [WEAK]
B .                                                                     跳转到外部函数
ENDP
HardFault_Handler\
PROC
EXPORT HardFault_Handler [WEAK]
B .
ENDP
SVC_Handler PROC
EXPORT SVC_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　　　　　　　　　　　　　　　　　　设置默认的中断函数入口
EXPORT Reserved16_IRQHandler [WEAK]
EXPORT Reserved17_IRQHandler [WEAK]
EXPORT Reserved18_IRQHandler [WEAK]
EXPORT Reserved19_IRQHandler [WEAK]
EXPORT Reserved20_IRQHandler [WEAK]
EXPORT FTMRE_IRQHandler [WEAK]
EXPORT LVD_LVW_IRQHandler [WEAK]
EXPORT IRQ_IRQHandler [WEAK]
EXPORT I2C0_IRQHandler [WEAK]
EXPORT I2C1_IRQHandler [WEAK]
EXPORT SPI0_IRQHandler [WEAK]
EXPORT SPI1_IRQHandler [WEAK]
EXPORT UART0_IRQHandler [WEAK]
EXPORT UART1_IRQHandler [WEAK]
EXPORT UART2_IRQHandler [WEAK]
EXPORT ADC0_IRQHandler [WEAK]
EXPORT ACMP0_IRQHandler [WEAK]
EXPORT FTM0_IRQHandler [WEAK]
EXPORT FTM1_IRQHandler [WEAK]
EXPORT FTM2_IRQHandler [WEAK]
EXPORT RTC_IRQHandler [WEAK]
EXPORT ACMP1_IRQHandler [WEAK]
EXPORT PIT_CH0_IRQHandler [WEAK]
EXPORT PIT_CH1_IRQHandler [WEAK]
EXPORT KBI0_IRQHandler [WEAK]
EXPORT KBI1_IRQHandler [WEAK]
EXPORT Reserved42_IRQHandler [WEAK]
EXPORT ICS_IRQHandler [WEAK]
EXPORT Watchdog_IRQHandler [WEAK]
EXPORT PWT_IRQHandler [WEAK]
EXPORT MSCAN_RX_IRQHandler [WEAK]
EXPORT MSCAN_TX_IRQHandler [WEAK]
EXPORT DefaultISR [WEAK]

Reserved16_IRQHandler
Reserved17_IRQHandler
Reserved18_IRQHandler
Reserved19_IRQHandler
Reserved20_IRQHandler
FTMRE_IRQHandler
LVD_LVW_IRQHandler
IRQ_IRQHandler
I2C0_IRQHandler
I2C1_IRQHandler
SPI0_IRQHandler
SPI1_IRQHandler
UART0_IRQHandler
UART1_IRQHandler
UART2_IRQHandler
ADC0_IRQHandler
ACMP0_IRQHandler
FTM0_IRQHandler
FTM1_IRQHandler
FTM2_IRQHandler
RTC_IRQHandler
ACMP1_IRQHandler
PIT_CH0_IRQHandler
PIT_CH1_IRQHandler
KBI0_IRQHandler
KBI1_IRQHandler
Reserved42_IRQHandler
ICS_IRQHandler
Watchdog_IRQHandler
PWT_IRQHandler
MSCAN_RX_IRQHandler
MSCAN_TX_IRQHandler
DefaultISR

B .

ENDP

ALIGN

; User Initial Stack & Heap                                  堆和栈初始化

IF :DEF:__MICROLIB　　　　　　　　　　　　　　　判断是否使用微库

EXPORT __initial_sp　　　　　　　　　　　　　　　 使用的话则将栈顶地址，堆始末地址赋予全局属
EXPORT __heap_base
EXPORT __heap_limit

ELSE　　　　　　　　　　　　　　　　　　　　　　　如果使用默认C库运行时

IMPORT __use_two_region_memory　　　　　　　定义全局标号__use_two_region_memory
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
                    　　　　　　　　　　　　　　　　　　;则进行堆栈和堆的赋值，在__main函数执行过程中调用
__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