DECΒΆ
- DEC M
- Decrement
- Description
- Decrements
M
by 1.M -= 1
- Results
- Allowed Instructions
Instruction Opcode CC (ADL/non-ADL) CC (.S) CC (.L) dec a $3D 1F X dec b $05 1F X dec c $0D 1F X dec d $15 1F X dec e $1D 1F X dec h $25 1F X dec l $2D 1F X dec ixh $DD, $25 2F X dec ixl $DD, $2D 2F X dec iyh $FD, $25 2F X dec iyl $FD, $2D 2F X dec (hl) $86 1F + 1R + 1W + 1 2F + 1R + 1W + 1 dec (ix+n) $DD, $35, n 3F + 1R + 1W + 1 4F + 1R + 1W + 1 dec (iy+n) $FD, $35, n 3F + 1R + 1W + 1 4F + 1R + 1W + 1 dec bc $ED, $0B 1F 2F dec de $ED, $1B 1F 2F dec hl $ED, $2B 1F 2F dec sp $ED, $3B 1F 2F dec ix $DD, $2B 2F 3F dec iy $ED, $2B 2F 3F - Notes
- While this instruction can be combined with a
jr nz,LoopLabel
to create a great 8-bit loop, usingdec
with a 16-bit or 24-bit operand will not alter the flags, so you’ll need another method of checking if the register pair is zero.
- While this instruction can be combined with a
- See Also
- INC