compare files inside nmake makefile

I would like to, within an nmake makefile, compare two files and then if
they are equal perform some action.

I have a compare program (cmp) that works. Not sure if thats a native XP
program or whether I downloaded it....but the program works . I'm using nmake
6.0.

I tried doing the below in nmake but I got an error after the cmp statement.

!if [cmp file1 file2] !=0
echo files match
!else
echo files don't match
!endif

The make error reports "unexpected file1 at this time", nmake fatal error
U1077

Anyway to do this?.... Other than the web, where is a good pdf reference on
nmake. I don't like the web format.

If this cannot be performed in a makefile but in a batch file, that would be
ok too.
Thnx for any help,
Kevin