Datasheet

PIC18F1220/1320
DS39605F-page 210 © 2007 Microchip Technology Inc.
DAW Decimal Adjust W Register
Syntax: [ label ] DAW
Operands: None
Operation: If [W<3:0> > 9] or [DC = 1] then
(W<3:0>) + 6 → W<3:0>;
else
(W<3:0>) → W<3:0>;
If [W<7:4> > 9] or [C = 1] then
(W<7:4>) + 6 → W<7:4>;
else
(W<7:4>) → W<7:4>;
Status Affected: C, DC
Encoding:
0000 0000 0000 0111
Description: DAW adjusts the eight-bit value in
W, resulting from the earlier addi-
tion of two variables (each in
packed BCD format) and produces
a correct packed BCD result. The
Carry bit may be set by DAW regard-
less of its setting prior to the DAW
instruction.
Words: 1
Cycles: 1
Q Cycle Activity:
Q1 Q2 Q3 Q4
Decode Read
register W
Process
Data
Write
W
Example 1:
DAW
Before Instruction
W=0xA5
C=0
DC = 0
After Instruction
W = 0x05
C=1
DC = 0
Example 2:
Before Instruction
W=0xCE
C=0
DC = 0
After Instruction
W = 0x34
C=1
DC = 0
DECF Decrement f
Syntax: [ label ] DECF f [,d [,a]]
Operands: 0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operation: (f) – 1 → dest
Status Affected: C, DC, N, OV, Z
Encoding:
0000 01da ffff ffff
Description: Decrement register ‘f’. If ‘d’ is ‘0’,
the result is stored in W. If ‘d’ is ‘1’,
the result is stored back in register
‘f’ (default). If ‘a’ is ‘0’, the Access
Bank will be selected, overriding
the BSR value. If ‘a’ = 1, then the
bank will be selected as per the
BSR value (default).
Words: 1
Cycles: 1
Q Cycle Activity:
Q1 Q2 Q3 Q4
Decode Read
register ‘f’
Process
Data
Write to
destination
Example:
DECF CNT
Before Instruction
CNT = 0x01
Z=0
After Instruction
CNT = 0x00
Z=1