DA14580 启动文件详解

转载地址:https://blog.csdn.net/dear_Wally/article/details/80317934

平台:  DA14580 官方 SDK5.4.0

软件:keil5

工程:\5.0.4\projects\target_apps\ble_examples\ble_app_all_in_one\Keil_5

boot_vectors.s 源文件:

;/**************************************************************************//**
; * @file     startup_ARMCM0.s
; * @brief    CMSIS Core Device Startup File for
; *           ARMCM0 Device Series
; * @version  V1.08
; * @date     23. November 2012
; *
; * @note
; *
; ******************************************************************************/
;/* Copyright (c) 2011 - 2012 ARM LIMITED
;
;   All rights reserved.
;   Redistribution and use in source and binary forms, with or without
;   modification, are permitted provided that the following conditions are met:
;   - Redistributions of source code must retain the above copyright
;     notice, this list of conditions and the following disclaimer.
;   - Redistributions in binary form must reproduce the above copyright
;     notice, this list of conditions and the following disclaimer in the
;     documentation and/or other materials provided with the distribution.
;   - Neither the name of ARM nor the names of its contributors may be used
;     to endorse or promote products derived from this software without
;     specific prior written permission.
;   *
;   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
;   AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
;   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
;   ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDERS AND CONTRIBUTORS BE
;   LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
;   CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
;   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
;   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
;   CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
;   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
;   POSSIBILITY OF SUCH DAMAGE.
;   ---------------------------------------------------------------------------*/
;/*
;//-------- <<< Use Configuration Wizard in Context Menu >>> ------------------
;*/

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

Stack_Size      EQU     0x00000600

                AREA    STACK, NOINIT, READWRITE, ALIGN=3
Stack_Mem       SPACE   Stack_Size
__initial_sp


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

Heap_Size       EQU     0x00000100

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


                PRESERVE8
                THUMB

;remap  uncomment below expression to have the application remap SYSRAM to 0
;__REMAP_SYSRAM EQU 1

; Vector Table Mapped to Address 0 at Reset

 ;               AREA    RESET, DATA, READONLY
                AREA    RESET,DATA, READONLY
                EXPORT  __Vectors
                EXPORT  __Vectors_End
                EXPORT  __Vectors_Size
				;ENTRY
__Vectors       DCD     __initial_sp              ; Top of Stack
                IF      :DEF:__REMAP_SYSRAM
                DCD     Reset_Handler+0x20000000             ; Reset Handler
                ELSE
                DCD     Reset_Handler             ; Reset Handler
                ENDIF
                DCD     NMI_Handler               ; NMI Handler
                DCD     HardFault_Handler         ; Hard Fault Handler
                DCD     0                         ; Reserved
                DCD     0                         ; Reserved
                DCD     0                         ; Reserved
                DCD     0                         ; Reserved
                DCD     0                         ; Reserved
                DCD     0                         ; Reserved
                DCD     0                         ; Reserved
                DCD     SVC_Handler               ; SVCall Handler
                DCD     0                         ; Reserved
                DCD     0                         ; Reserved
                DCD     PendSV_Handler            ; PendSV Handler
                DCD     SysTick_Handler           ; SysTick Handler
               
                DCD     BLE_WAKEUP_LP_Handler            				
                DCD     BLE_FINETGTIM_Handler     
                DCD     BLE_GROSSTGTIM_Handler    
                DCD     BLE_CSCNT_Handler          
                DCD     BLE_SLP_Handler 
                DCD     BLE_ERROR_Handler 
                DCD     BLE_RX_Handler
                DCD     BLE_EVENT_Handler	                
                DCD     SWTIM_Handler
                DCD     WKUP_QUADEC_Handler	
                DCD     BLE_RF_DIAG_Handler	
                DCD     BLE_CRYPT_Handler	
                DCD     UART_Handler		
                DCD     UART2_Handler    
                DCD     I2C_Handler    
                DCD     SPI_Handler    
                DCD     ADC_Handler    
                DCD     KEYBRD_Handler    
                DCD     RFCAL_Handler    
                DCD     GPIO0_Handler
                DCD     GPIO1_Handler
                DCD     GPIO2_Handler
                DCD     GPIO3_Handler
                DCD     GPIO4_Handler
__Vectors_End

__Vectors_Size         EQU     __Vectors_End - __Vectors
                AREA    |.text|, CODE, READONLY


; Reset Handler

Reset_Handler   PROC
                EXPORT  Reset_Handler             [WEAK]
                IMPORT  __main
                IMPORT  SystemInit
				
;remap 
                IF      :DEF:__REMAP_SYSRAM
                LDR     R0, =0x0
                LDR     R1, [R0]
                LDR     R0, =0x20000000
                LDR     R2, [R0]
                CMP     R2, R1
                BEQ     remap_done
                LDR     R0, =0x50000012
                LDRH    R1, [R0]
                LSRS    R2, R1, #2
                LSLS    R1, R2, #2
                MOVS    R2, #0x2
                ADDS    R1, R1, R2            ;remap SYSRAM to 0
                LSLS    R2, R2, #14
                ADDS    R1, R1, R2         ;SW RESET
                STRH    R1, [R0]
remap_done                
                ENDIF
;remap

                LDR     R0, =SystemInit
                BLX     R0
                LDR     R0, =__main
                BX      R0
                ENDP


; Dummy Exception Handlers (infinite loops which can be modified)
                IMPORT NMI_HandlerC
NMI_Handler\
                PROC
                movs r0, #4
                mov r1, lr
                tst r0, r1
                beq NMI_stacking_used_MSP
                mrs r0, psp
                ldr r1,=NMI_HandlerC
                bx r1
NMI_stacking_used_MSP
                mrs r0, msp
                ldr r1,=NMI_HandlerC
                bx r1
                ENDP
                
                IMPORT HardFault_HandlerC
HardFault_Handler\
                PROC
                movs r0, #4
                mov r1, lr
                tst r0, r1
                beq HardFault_stacking_used_MSP
                mrs r0, psp
                ldr r1,=HardFault_HandlerC
                bx r1
HardFault_stacking_used_MSP
                mrs r0, msp
                ldr r1,=HardFault_HandlerC
                bx r1
                ENDP

				
				IMPORT SVC_Handler_c
SVC_Handler     PROC
                movs r0, #4
                mov r1, lr
                tst r0, r1
                beq SVC_stacking_used_MSP
                mrs r0, psp
                ldr r1,=SVC_Handler_c
                bx r1
SVC_stacking_used_MSP
                mrs r0, msp
                ldr r1,=SVC_Handler_c
                bx r1
                ENDP
PendSV_Handler  PROC
                EXPORT  PendSV_Handler            [WEAK]
                B       .
                ENDP
SysTick_Handler PROC
                EXPORT  SysTick_Handler            [WEAK]
                B       .
                ENDP
Default_Handler PROC
                EXPORT BLE_WAKEUP_LP_Handler   [WEAK]
                EXPORT BLE_FINETGTIM_Handler   [WEAK]
                EXPORT BLE_GROSSTGTIM_Handler  [WEAK]
                EXPORT BLE_CSCNT_Handler       [WEAK]
                EXPORT BLE_SLP_Handler         [WEAK]
                EXPORT BLE_ERROR_Handler       [WEAK]
                EXPORT BLE_RX_Handler          [WEAK]
                EXPORT BLE_EVENT_Handler	   [WEAK]
                EXPORT SWTIM_Handler           [WEAK]
                EXPORT WKUP_QUADEC_Handler     [WEAK]
                EXPORT BLE_RF_DIAG_Handler     [WEAK]
				EXPORT BLE_CRYPT_Handler	   [WEAK]
                EXPORT UART_Handler		       [WEAK]
                EXPORT UART2_Handler           [WEAK]
                EXPORT I2C_Handler             [WEAK]
                EXPORT SPI_Handler             [WEAK]
                EXPORT ADC_Handler             [WEAK]
                EXPORT KEYBRD_Handler          [WEAK]
                EXPORT RFCAL_Handler           [WEAK]
                EXPORT GPIO0_Handler           [WEAK]
                EXPORT GPIO1_Handler           [WEAK]
                EXPORT GPIO2_Handler           [WEAK]
                EXPORT GPIO3_Handler           [WEAK]
                EXPORT GPIO4_Handler           [WEAK]
               
				
BLE_WAKEUP_LP_Handler
BLE_FINETGTIM_Handler     
BLE_GROSSTGTIM_Handler    
BLE_CSCNT_Handler          
BLE_SLP_Handler 
BLE_ERROR_Handler 
BLE_RX_Handler
BLE_EVENT_Handler	
SWTIM_Handler
WKUP_QUADEC_Handler 	
BLE_RF_DIAG_Handler 
BLE_CRYPT_Handler	
UART_Handler		
UART2_Handler    
I2C_Handler    
SPI_Handler    
ADC_Handler    
KEYBRD_Handler    
RFCAL_Handler    
GPIO0_Handler
GPIO1_Handler
GPIO2_Handler
GPIO3_Handler
GPIO4_Handler
               B       .
               ENDP

                ALIGN


; User Initial Stack & Heap

                IF      :DEF:__MICROLIB

                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

下面为转载,针对每条语句的详细讲解:

1 、启动文件简介

DA14580的启动文件为boot_vectors.s,启动文件由汇编编写,是系统上电复位后第一个执行的程序。主要做了以下工作:

1.1、初始化堆栈指针 SP =__initial_sp

1.2、初始化PC指针   =Reset_Handler

1.3、初始化中断向量表

1.4、配置系统时钟

1.5、调用C库函数_main初始化用户堆栈,从而最终调用main函数去到C的世界
 

3、启动文件代码讲解


3.1、Stack栈配置

    Stack_Size      EQU     0x00000600
                    AREA    STACK, NOINIT, READWRITE, ALIGN=3
    Stack_Mem       SPACE   Stack_Size
    __initial_sp

开辟栈的大小为0X00000600(1.5KB),名字为STACK,NOINIT即不初始化,可读可写,8(2^3)字节对齐。

栈的作用是用于局部变量,函数调用,函数形参等的开销,栈的大小不能超过内部SRAM的大小。如果编写的程序比较大,定义的局部变量很多,那么就需要修改栈的大小。如果某一天,你写的程序出现了莫名奇怪的错误,并进入了硬fault的时候,这时你就要考虑下是不是栈不够大,溢出了。


EQU:宏定义的伪指令,相当于等于,类似与C中的define。

AREA:告诉汇编器汇编一个新的代码段或者数据段。STACK表示段名,这个可以任意命名;NOINIT表示不初始化;READWRITE表示可读可写,ALIGN=3,表示按照2^3对齐,即8字节对齐。

SPACE:用于分配一定大小的内存空间,单位为字节。这里指定大小等于Stack_Size。


标号__initial_sp紧挨着SPACE语句放置,表示栈的结束地址,即栈顶地址,栈是由高向低生长的。


3.2、Heap堆配置

    Heap_Size          EQU     0x00000100

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

开辟堆的大小为0X00000100(256字节),名字为HEAP,NOINIT即不初始化,可读可写,8(2^3)字节对齐。__heap_base表示堆的起始地址,__heap_limit表示堆的结束地址。堆是由低向高生长的,跟栈的生长方向相反。

堆主要用来动态内存的分配,像malloc()函数申请的内存就在堆上面。


    PRESERVE8

    THUMB

PRESERVE8:指定当前文件的堆栈按照8字节对齐。

THUMB:表示后面指令兼容THUMB指令。THUBM是ARM以前的指令集,16bit,现在Cortex-M系列的都使用THUMB-2指令集,THUMB-2是32位的,兼容16位和32位的指令,是THUMB的超级。


3.3、向量表

                AREA    RESET,DATA, READONLY
                EXPORT  __Vectors
                EXPORT  __Vectors_End

                EXPORT  __Vectors_Size

定义一个数据段,名字为RESET,可读。并声明__Vectors、__Vectors_End和__Vectors_Size这三个标号具有全局属性,可供外部的文件调用。

EXPORT:声明一个标号可被外部的文件使用,使标号具有全局属性。如果是IAR编译器,则使用的是GLOBAL这个指令。

当内核响应了一个发生的异常后,对应的异常服务例程(ESR)就会执行。为了决定ESR 的入口地址,内核使用了"向量表查表机制"。这里使用一张向量表。向量表其实是一个WORD(32 位整数)数组,每个下标对应一种异常,该下标元素的值则是该ESR 的入口地址。向量表在地址空间中的位置是可以设置的,通过NVIC 中的一个重定位寄存器来指出向量表的地址。在复位后,该寄存器的值为0。因此,在地址0 (即FLASH 地址0)处必须包含一张向量表,用于初始时的异常分配。要注意的是这里有个另类:0 号类型并不是什么入口地址,而是给出了复位后MSP 的初值。

; Vector Table Mapped to Address 0 at Reset

 ;               AREA    RESET, DATA, READONLY
                AREA    RESET,DATA, READONLY
                EXPORT  __Vectors
                EXPORT  __Vectors_End
                EXPORT  __Vectors_Size
				;ENTRY
__Vectors       DCD     __initial_sp              ; Top of Stack
                IF      :DEF:__REMAP_SYSRAM
                DCD     Reset_Handler+0x20000000             ; Reset Handler
                ELSE
                DCD     Reset_Handler             ; Reset Handler
                ENDIF
                DCD     NMI_Handler               ; NMI Handler
                DCD     HardFault_Handler         ; Hard Fault Handler
                DCD     0                         ; Reserved
                DCD     0                         ; Reserved
                DCD     0                         ; Reserved
                DCD     0                         ; Reserved
                DCD     0                         ; Reserved
                DCD     0                         ; Reserved
                DCD     0                         ; Reserved
                DCD     SVC_Handler               ; SVCall Handler
                DCD     0                         ; Reserved
                DCD     0                         ; Reserved
                DCD     PendSV_Handler            ; PendSV Handler
                DCD     SysTick_Handler           ; SysTick Handler
               
                DCD     BLE_WAKEUP_LP_Handler            				
                DCD     BLE_FINETGTIM_Handler     
                DCD     BLE_GROSSTGTIM_Handler    
                DCD     BLE_CSCNT_Handler          
                DCD     BLE_SLP_Handler 
                DCD     BLE_ERROR_Handler 
                DCD     BLE_RX_Handler
                DCD     BLE_EVENT_Handler	                
                DCD     SWTIM_Handler
                DCD     WKUP_QUADEC_Handler	
                DCD     BLE_RF_DIAG_Handler	
                DCD     BLE_CRYPT_Handler	
                DCD     UART_Handler		
                DCD     UART2_Handler    
                DCD     I2C_Handler    
                DCD     SPI_Handler    
                DCD     ADC_Handler    
                DCD     KEYBRD_Handler    
                DCD     RFCAL_Handler    
                DCD     GPIO0_Handler
                DCD     GPIO1_Handler
                DCD     GPIO2_Handler
                DCD     GPIO3_Handler
                DCD     GPIO4_Handler
__Vectors_End

__Vectors_Size         EQU     __Vectors_End - __Vectors

 

__Vectors为向量表起始地址,__Vectors_End 为向量表结束地址,两个相减即可算出向量表大小。

向量表从FLASH的0地址开始放置,以4个字节为一个单位,地址0存放的是栈顶地址,0X04存放的是复位程序的地址,以此类推。从代码上看,向量表中存放的都是中断服务函数的函数名,可我们知道C语言中的函数名就是一个地址。

DCD:分配一个或者多个以字为单位的内存,以四字节对齐,并要求初始化这些内存。在向量表中,DCD分配了一堆内存,并且以ESR的入口地址初始化它们。


3.4、复位程序

                AREA    |.text|, CODE, READONLY

定义一个名称为.text的代码段,可读。

; Reset Handler

Reset_Handler   PROC
                EXPORT  Reset_Handler             [WEAK]
                IMPORT  __main
                IMPORT  SystemInit
				
;remap 
                IF      :DEF:__REMAP_SYSRAM
                LDR     R0, =0x0
                LDR     R1, [R0]
                LDR     R0, =0x20000000
                LDR     R2, [R0]
                CMP     R2, R1
                BEQ     remap_done
                LDR     R0, =0x50000012
                LDRH    R1, [R0]
                LSRS    R2, R1, #2
                LSLS    R1, R2, #2
                MOVS    R2, #0x2
                ADDS    R1, R1, R2            ;remap SYSRAM to 0
                LSLS    R2, R2, #14
                ADDS    R1, R1, R2         ;SW RESET
                STRH    R1, [R0]
remap_done                
                ENDIF
;remap

                LDR     R0, =SystemInit
                BLX     R0
                LDR     R0, =__main
                BX      R0
                ENDP

 

复位子程序是系统上电后第一个执行的程序,调用SystemInit函数初始化系统时钟,然后调用C库函数_mian,最终调用main函数去到C的世界。

WEAK:表示弱定义,如果外部文件优先定义了该标号则首先引用该标号,如果外部文件没有声明也不会出错。这里表示复位子程序可以由用户在其他文件重新实现,这里并不是唯一的。

IMPORT:表示该标号来自外部文件,跟C语言中的EXTERN关键字类似。这里表示SystemInit和__main这两个函数均来自外部的文件。

SystemInit()是一个标准的库函数,在system_ARMCM0.c这个文件中定义。主要作用是配置系统时钟。

__main是一个标准的C库函数,主要作用是初始化用户堆栈,最终调用main_func函数去到C的世界。

3.5、中断服务程序

在启动文件里面已经帮我们写好所有中断的中断服务函数,跟我们平时写的中断服务函数不一样的就是这些函数都是空的,真正的中断复服务程序需要我们在外部的C文件里面重新实现,这里只是提前占了一个位置而已。

如果我们在使用某个外设的时候,开启了某个中断,但是又忘记编写配套的中断服务程序或者函数名写错,那当中断来临的时,程序就会跳转到启动文件预先写好的空的中断服务程序中,并且在这个空函数中无限循环,即程序就死在这里。

; Dummy Exception Handlers (infinite loops which can be modified)
                IMPORT NMI_HandlerC
NMI_Handler\
                PROC
                movs r0, #4
                mov r1, lr
                tst r0, r1
                beq NMI_stacking_used_MSP
                mrs r0, psp
                ldr r1,=NMI_HandlerC
                bx r1
NMI_stacking_used_MSP
                mrs r0, msp
                ldr r1,=NMI_HandlerC
                bx r1
                ENDP
                
                IMPORT HardFault_HandlerC
HardFault_Handler\
                PROC
                movs r0, #4
                mov r1, lr
                tst r0, r1
                beq HardFault_stacking_used_MSP
                mrs r0, psp
                ldr r1,=HardFault_HandlerC
                bx r1
HardFault_stacking_used_MSP
                mrs r0, msp
                ldr r1,=HardFault_HandlerC
                bx r1
                ENDP

				
				IMPORT SVC_Handler_c
SVC_Handler     PROC
                movs r0, #4
                mov r1, lr
                tst r0, r1
                beq SVC_stacking_used_MSP
                mrs r0, psp
                ldr r1,=SVC_Handler_c
                bx r1
SVC_stacking_used_MSP
                mrs r0, msp
                ldr r1,=SVC_Handler_c
                bx r1
                ENDP
PendSV_Handler  PROC
                EXPORT  PendSV_Handler            [WEAK]
                B       .
                ENDP
SysTick_Handler PROC
                EXPORT  SysTick_Handler            [WEAK]
                B       .
                ENDP
Default_Handler PROC
                EXPORT BLE_WAKEUP_LP_Handler   [WEAK]
                EXPORT BLE_FINETGTIM_Handler   [WEAK]
                EXPORT BLE_GROSSTGTIM_Handler  [WEAK]
                EXPORT BLE_CSCNT_Handler       [WEAK]
                EXPORT BLE_SLP_Handler         [WEAK]
                EXPORT BLE_ERROR_Handler       [WEAK]
                EXPORT BLE_RX_Handler          [WEAK]
                EXPORT BLE_EVENT_Handler	   [WEAK]
                EXPORT SWTIM_Handler           [WEAK]
                EXPORT WKUP_QUADEC_Handler     [WEAK]
                EXPORT BLE_RF_DIAG_Handler     [WEAK]
				EXPORT BLE_CRYPT_Handler	   [WEAK]
                EXPORT UART_Handler		       [WEAK]
                EXPORT UART2_Handler           [WEAK]
                EXPORT I2C_Handler             [WEAK]
                EXPORT SPI_Handler             [WEAK]
                EXPORT ADC_Handler             [WEAK]
                EXPORT KEYBRD_Handler          [WEAK]
                EXPORT RFCAL_Handler           [WEAK]
                EXPORT GPIO0_Handler           [WEAK]
                EXPORT GPIO1_Handler           [WEAK]
                EXPORT GPIO2_Handler           [WEAK]
                EXPORT GPIO3_Handler           [WEAK]
                EXPORT GPIO4_Handler           [WEAK]
               
				
BLE_WAKEUP_LP_Handler
BLE_FINETGTIM_Handler     
BLE_GROSSTGTIM_Handler    
BLE_CSCNT_Handler          
BLE_SLP_Handler 
BLE_ERROR_Handler 
BLE_RX_Handler
BLE_EVENT_Handler	
SWTIM_Handler
WKUP_QUADEC_Handler 	
BLE_RF_DIAG_Handler 
BLE_CRYPT_Handler	
UART_Handler		
UART2_Handler    
I2C_Handler    
SPI_Handler    
ADC_Handler    
KEYBRD_Handler    
RFCAL_Handler    
GPIO0_Handler
GPIO1_Handler
GPIO2_Handler
GPIO3_Handler
GPIO4_Handler
               B       .
               ENDP

3.6、用户堆栈初始化

        ALIGN                            

ALIGN:对指令或者数据存放的地址进行对齐,后面会跟一个立即数。缺省表示4字节对齐。

; User Initial Stack & Heap

                IF      :DEF:__MICROLIB

                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

判断是否定义了__MICROLIB ,如果定义了则赋予标号__initial_sp(栈顶地址)、__heap_base(堆起始地址)、__heap_limit(堆结束地址)全局属性,可供外部文件调用。如果没有定义(实际的情况就是我们没定义__MICROLIB)则使用默认的C库,然后初始化用户堆栈大小,这部分有C库函数__main来完成,当初始化完堆栈之后,就调用main_func函数去到C的世界。

IF,ELSE,ENDIF:汇编的条件分支语句,跟C语言的if ,else类似

END:文件结束
 

转自:https://blog.csdn.net/dear_Wally/article/details/80317934

猜你喜欢

转载自blog.csdn.net/jiangchao3392/article/details/84889253
今日推荐