converting Biginteger to Bytearray(Raw data)

Question

Hi i have used the following code for converting the bigint in decimal to bytearray (raw data) , but i am getting wrong result What is the mistake here.

I am trying this in Apple Mac ( for Iphone app) COMP_BYTE_SIZE is 4

Is there any bigendian/ little endian issue , please Help.

void bi_export(BI_CTX *ctx, bigint *x, uint8_t *data, int size)
{
    int i, j, k = size-1;

    check(x);
    memset(data, 0, size);  /* ensure all leading 0's are cleared */

    for (i = 0; i < x->size; i++)
    {
        for (j = 0; j < COMP_BYTE_SIZE; j++)
        {
            comp mask = 0xff << (j*8);
            int num = (x->comps[i] & mask) >> (j*8);
            data[k--] = num;

            if (k < 0)
            {
                break;
            }
        }
    }

Thanks

Answer 1

The argument size is at least x->size*4, ie. the target array is big enough? Also use

comp mask = (comp)0xff << (j*8);

Answer 2

num should be cast to uint8_t before copy

data[k--] = (uint8_t)num;