复习C语言内嵌汇编初级(2)

 1 # include 
 2 
 3 int main()
 4 {
 5         int i = 100;
 6         int ret = 0;
 7 
 8         int *p = &i;
 9         //ret = *p;
10         __asm__(
11                 "ldr %0, [%1]"
12 
13                 :"+r" (ret)       //输出
14                 :"r"  (p)       //输入
15         );
16         printf("hello world! %d\n", ret);
17 }

 1 #include 
 2 
 3 int main()
 4 {
 5         int i = 6;
 6         int ret = 0;
 7 
 8         //i = 100;
 9         __asm__(
10                 "mov r0, #100\n"
11                 "str r0, [%1]\n"
12                 //"ldr r0, [%1]\n"
13 
14                 : "+r" (ret)    //输出
15                 : "r" (&i)
16         );
17 
18         printf("i %d\n", i);
19 }

 1 #include 
 2 
 3 int main()
 4 {
 5         int arr[3] = {0};
 6 
 7         __asm__(
 8                 "mov r0, #1\n"
 9                 "str r0, [%0, #0]\n"
10                 "add r0, r0, #1\n"
11                 "str r0, [%0, #4]\n"
12                 "add r0, r0, #1\n"
13                 "str r0, [%0, #8]\n"
14 
15                 : //"+r" (arr)  //error
16                 : "r" (arr)
17                 : "r0"
18         );
19 
20         printf("arr[0] %d\n", arr[0]);
21         printf("arr[1] %d\n", arr[1]);
22         printf("arr[2] %d\n", arr[2]);
23 }

 1 #include 
 2 
 3 int main()
 4 {
 5         int arr[3] = {1, 2, 3};
 6         int i = 10; 
 7         int p = 0;
 8 
 9         __asm__(
10                 //"ldr %0, [%2]\n"   //addr and value not change
11                 //"ldr %0, [%2, #4]\n" //addr not change, value change
12                 //"ldr %0, [%2, #4]!\n" //addr change, value change
13                 "ldr %0, [%2], #4\n" //addr change, value not change
14                 "mov %1, %2\n"
15     
16                 : "+r" (i), "+r" (p)  //error
17                 : "r" (arr)
18                 : "r0"
19         );
20     
21         printf("i is:  %d\n", i);
22         printf("p   is:  %x\n", p); 
23         printf("arr is:  %x\n", arr);
24 }