Yes, but UINT64 is unsigned.Originally Posted by Elysia
Yes, but UINT64 is unsigned.
Yes, I know. I didn't think of it then, but come to think of it now, of course it's 2 ^ 64, since a signed only has half the range.
As originally stated, the max UINT64 is 2^64-1, period.
Ah except you forgot one thing. The data types being used cannot represent negative numbers. In the theoretical case you gave, -96 would be represented as 4 in your unsigned type.count1 = 98
count2 = 2
diff = 2-98 = -96
actual diff = 4...But only if I know that the size of the counter is 100...and I don't know the size of the counter...
A better example is where 255 is the max. Take finish = 5, start = 250. Finish-start = 5-250 = -245. Now lets put that into a byte. The lowest 8 bits are: 00001011. Viola that equals 10.
Basically it is always safe to directly subtract two unsigned numbers that are based on a timer to get the correct answer. It only fails when the duration really does exceed the maximum value of the timer.
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00001011 = 0x0B = 11
Else, how i personaly see unsigned integer substraction, is "substract the 2 numbers and forget about the remaining burrow". Example
You can also add the first term with the opposite of the second term. This is how processors implements substraction. ExampleCode:0 5 - F A 1 1 // burrow line ----- 0 B
I'm just throwing out this extra information for people who could be interested.Code:F A --- // 15 complement 0 5 --- // + 1 (Two complement) 0 6 0 5 + 0 6 ----- 0 B
