DEC        fr        Decrement fr

Words:        1        Cycles:        1                Affects:        Z

Operation:        Fr is decremented. Z will be set to 1 if the result was 0, otherwise Z will be cleared to 0.

Coding:        DECF                fr,1

DECSZ        fr        Decrement fr and skip if zero

Words:        1        Cycles:        1 or 2 (skip)        Affects:        none

Operation:        Fr is decremented. The next instruction word will be skipped if the result was 0.

Coding:        DECFSZ        fr,1

Note:        Only one word is skipped by this instruction. To avoid strange results, make sure that any instruction following DECSZ is a single-word instruction.

DJNZ        fr,addr9        Decrement fr and jump if not zero

Words:        2        Cycles:        2 or 3 (jump)        Affects:        none

Operation:        Fr is decremented. If the result is not 0, a jump to addr9 is executed.

Coding:        DECFSZ        fr,1

       GOTO        addr9