Is it possible to have a 64bit Integer addition in C?

Check whether your compiler supports 64-bit long-longs. Otherwise:

"But how to manage the carry from low to high?"

For unsigned arithmetic 32-bit addition should "wrap" (overflow) modulo 2^32 predictably, which you can detect and use as the carry.

Check whether your compiler supports 64-bit long-longs. Otherwise:

"But how to manage the carry from low to high?"

For unsigned arithmetic 32-bit addition should "wrap" (overflow) modulo 2^32 predictably, which you can detect and use as the carry.

For unsigned arithmetic 32-bit addition should "wrap" (overflow) modulo 2^32 predictably, which you can detect and use as the carry.


i hope you can show me a little example,
sorry i'am an absoulute beginner in C

:-)

Which particular ARM compiler are you using?

Further to this thread

http://www.keil.com/forum/docs/thread7615.asp

I think that GCC supports the 'long long' type to give 64 bits?

You may find that your compiler is similar.

You will, of course, need to check in the Manual

Oops - Dan had already said that!

"i hope you can show me a little example"

struct U64 {
    unsigned long msl;
    unsigned long lsl;
};

struct U64 U64_sum(struct U64 augend, struct U64 addend)
{
    struct U64 sum;

    sum.msl = augend.msl + addend.msl;
    sum.lsl = augend.lsl + addend.lsl;

    if (sum.lsl < augend.lsl)   /* Carry? */
        ++sum.msl;

    return sum;
}