Can someone explain section alignment for me? I read two conflicting documents on the subject.

One source says it must be multiples of two, but the FASM docs point out it must be power of two.

I'm no mathematician, but I'm pretty sure these are totally different.

2, 4, 6, 8, ...

vs

1, 4, 9, 16, ...

Or something else?

Actually it is

2,4,6,8,10, ...
vs
2,4,8,16,32,64,...

I am not completely sure, but I think that it is about power of 2. But there is another problem. On win95/98 these values are constant and are equal to 512 for FileAlignment and 4096 for SectionAlignment. Files compiled with other values, won't work on other than NT platforms. So if you want to remain compatible with older versions of windows, you should stay with these values. But we have a small advantage. Because as you know, if we have even only one byte in section, it will pad it with zeroes to these 512 needed by the FileAlignment. But, we can truncate these zeroes if they are in the last section. Such file will work fine on all windowses

yes, they must be power of two (which are also multiples of two )

Thanks for the replies.

My understanding now is that it must be:

2^n

Where n = { 1 .. 13 }