嵌入式考试
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2012-01-05
19:22:07
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Arm 汇编:打印“hello world”
AREA codesec,CODE,READONLY//main PROC//STMFD sp!,[lr]//ADR r0,strhello//BL
_printf//LDMFD sp!,[pc]//AREA constdatasec,CODE,READWRITE//strhello DCB
“HelloWorld ”//ENDP//EXPORT main//IMPORT _main//IMPORT __main//IMPORT
_printf//IMPORT ||Lib$$Request$$armlib||,WEAK//END
Arm 汇编:字符串复制函数
AREA StrCopy,CODE,READONLY//ENTRY//start//LDR r1,=srcstr//LDR r2,=dststr//BL
strcopy//stop//MOV r0,#0x18//LDR r1,=0x20026//SWI 0x123456//strcopy//LDRB r2,[r1],#1
//STRB r2,[r0],#1//CMP r2,#0//BNE strcopy//MOV pc,lr//AREA
Strings,DATA,READWRITE//srcstr DCB “first string-source”，0//dststr DCB “Second string-
destination”，0//END
C 语言中内嵌汇编
#include <stdio.h>
//void my_strcpy(char* src, const char* dst){//int ch;// __asm{//loop://LDRB ch, [src], #1//STRB
ch, [dst], #1//CMP ch, #0//BNE loop};//}
//int main(void){//const char* a = "Hello World!";//char b[20];//__asm{//MOV R0, a//MOV R1,
b//BL my_strcpy, {R0, R1}//};//printf("Original String: %s",a);//printf(“Copied String: %s\
n",b);//return 0;//}
C 语言中调用汇编程序
#include <stdio.h>
//extern void strcopy(char *d, const char *s);
//int main()
//{ const char *srcstr = "First string - source";//char dststr[] = "Second string -
destination";//printf("Before copying:\n");//printf(" '%s' '%s'\
n",srcstr,dststr);//strcopy(dststr,srcstr);//printf("After copying:");//printf(" '%s' '%s'\
n",srcstr,dststr);//return 0;//}
//AREA SCopy, CODE, READONLY//EXPORT strcopy
//strcopy //LDRB r2, [r1],#1 ; load byte and update address//STRB r2, [r0],#1 ;
store byte and update address;//CMP r2, #0 ; check for zero terminator //BNE strcopy
; keep going if not//MOV pc,lr ; Return//END
c 程序 g（）返回 5 个整数的和
int g（int a, int b, int c, int d, int e）{
return a + b + c + d + e;}
;汇编程序调用 c 程序 g（）计算 5 个整数 i, 2*i, 3*i, 4*i, 5*i 的和
EXPORT f//AREA f, CODE, READONLY
//IMPORT g //STR lr, [sp,#-4]! //ADD r1, r0, r0 //
ADD r2, r1, r0 //ADD r3, r1, r2 //STR r3, [sp, #-4]! //ADD r3, r1, r1 //BL
g //ADD sp, sp, #4 //LDR pc, [sp], #4 //END
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