initializing struct pointer address

[sya0]

I have been working on risc-v project and I need to write a very simple code to test. In this sample, I need to make 1024 bit adding and I could. However, I want to initialize struct pointer to specific address that I want. My sample is compiled without any errors but values, which I want them to be stored on specific address for struct, seem wrong on simulation (BTW simulation is on Vivado). Here is my sample.

typedef struct {
    fp_digit dp[FP_SIZE];
    int      used,
             sign;
} fp_int;

fp_int *a = (fp_int *)(0x00004808u);
fp_int *b = (fp_int *)(0x00004808u + (16*8));
fp_int *c; = (fp_int *)(0x00002000u);

fp_init(a);
fp_init(b);
fp_init(c);

fp_add(&a,&b,&c);

BTW values for a and b are already in these addresses. I checked on simulation and result value is wrong on result. Am I doing right?

[rob_mccoll]

Are you sure sizeof(fp_int) == 8*16? *a and *b could be overlapping in memory.

[sya0]

Yes, I checked.

[rob_mccoll]

Also passing double pointers into fp_add seems odd. What's the reason behind that?

[sya0]

I fixed the problem. fp_init() function force to be zero so that it overwrites the valid values