Rabbit 2000, Reference Manual, Page: 33 / 120

Instruction Reference Manual 29
Description
Decrements the data in index register IX or IY.
Description
Decrements the data in the register r (any of the registers A, B, C, D, E, H, or L).
DEC IX
DEC IY
Opcode Instruction Clocks Operation
DD 2B DEC IX 4 (2,2) IX = IX - 1
FD 2B DEC IY 4(2,2) IY = IY - 1
Flags ALTD I/O
S Z L/V C F R SP S D
- - - -
DEC r
Opcode Instruction Clocks Operation
——
3D
05
0D
15
1D
25
2D
DEC r
DEC A
DEC B
DEC C
DEC D
DEC E
DEC H
DEC L
2
2
2
2
2
2
2
2
r = r - 1
A = A - 1
B = B - 1
C = C - 1
D = D - 1
E = E - 1
H = H - 1
L = L - 1
Flags ALTD I/O
S Z L/V C F R SP S D
• • V - • •