The Art of Assembly Language, 2nd Edition

7.5 "Medium-Level" Control Structures: jt and jf

HLA provides two special conditional jump instructions: jt ( jump if true) and jf ( jump if false). These instructions take the following syntax:

jt( boolean_expression ) target_label;
jf( boolean_expression ) target_label;

The boolean_expression is the standard HLA boolean expression allowed by if..endif and other HLA high-level language statements. These instructions evaluate the boolean expression and jump to the specified label if the expression evaluates true (jt) or false (jf).

These are not real 80x86 instructions. HLA compiles them into a sequence of one or more 80x86 machine instructions that achieve the same result. In general, you should not use these two instructions in your main code; ...