Help improving a simple assembly function
- by MPelletier
I just handed in this function in an assignment. It is done (hence no homework tag). But I would like to see how this can be improved.
Essentially, the function sums the squares of all the integers between 1 and the given number, using the following formula:
n(n+1)(2n+1)/6
Where n is the maximum number.
The function below is made to catch any overflow and return 0 should any occur.
UInt32 sumSquares(const UInt32 number)
{
int result = 0;
__asm
{
mov eax, number //move number in eax
mov edx, 2 //move 2 in edx
mul edx //multiply (2n)
jo end //jump to end if overflow
add eax, 1 //addition (2n+1)
jo end //jump to end if overflow
mov ecx, eax //move (2n+1) in ecx
mov ebx, number //move number in ebx
add ebx, 1 //addition (n+1)
jo end //jump to end if overflow
mov eax, number //move number in eax for multiplication
mul ebx //multiply n(n+1)
jo end //jump to end if overflow
mul ecx //multiply n(n+1)(2n+1)
jo end //jump to end if overflow
mov ebx, 6 //move 6 in ebx
div ebx //divide by 6, the result will be in eax
mov result, eax //move eax in result
end:
}
return result;
}
Basically, I want to know what I can improve in there. In terms of best-practices mostly. One thing sounds obvious: smarter overflow check (with a single check for whatever maximum input would cause an overflow).
