Datasheet

PIC18FXX8
DS41159E-page 300 © 2006 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
Encoding: 0000 0000 0000 0111
Description: DAW adjusts the eight-bit value in W
resulting from the earlier addition of two
variables (each in packed BCD format)
and produces a correct packed BCD
result.
Words: 1
Cycles: 1
Q Cycle Activity:
Q1 Q2 Q3 Q4
Decode Read
register W
Process
Data
Write
W
Exam
ple 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