CJNE & DJNZ Instructions

CJNE (Compare and Jump if Not Equal): Four variants:

• CJNE A,direct,rel
• CJNE A,#data,rel
• CJNE Rn,#data,rel
• CJNE @Ri,#data,rel
  Operation: CY=1 if first < second, else 0; if not equal, PC←PC+rel else next. Does not store result, only sets CY and jumps. Example:

CJNE A,#10H,NOTEQ ; if A ≠10H jump

Use for compare, sorting.

DJNZ (Decrement & Jump if Not Zero): Two variants: DJNZ direct,rel, DJNZ Rn,rel. Decrement operand, if ≠0 jump. Useful for loops:

MOV R2,#10
LOOP: DJNZ R2,LOOP ; iterate 10 times

Neither affects flags except CY for CJNE; DJNZ affects none except operand.