The Art of Assembly Language, 2nd Edition

7.7 Introduction to Decisions

In its most basic form, a decision is some sort of branch within the code that switches between two possible execution paths based on some condition. Normally (though not always), conditional instruction sequences are implemented with the conditional jump instructions. Conditional instructions correspond to the if..then..endif statement in HLA:

if( expression ) then
          << statements >>
     endif;

Assembly language, as usual, offers much more flexibility when dealing with conditional statements. Consider the following C/C++ statement:

if( (( x < y ) && ( z > t )) || ( a != b ) )
          stmt1;

A "brute force" approach to converting this statement into assembly language might produce the following:

mov( x, eax ); cmp( eax, y ); setl( bl ...