Datasheet

PIC18F2220/2320/4220/4320
DS39599G-page 298 © 2007 Microchip Technology Inc.
TSTFSZ Test f, Skip if 0
Syntax: [ label ] TSTFSZ f [,a]
Operands: 0 ≤ f ≤ 255
a ∈ [0,1]
Operation: skip if f = 0
Status Affected: None
Encoding:
0110 011a ffff ffff
Description: If ‘f’ = 0, the next instruction,
fetched during the current instruc-
tion execution is discarded and a
NOP is executed, making this a
two-cycle instruction. If ‘a’ is ‘0’, the
Access Bank will be selected, over-
riding the BSR value. If ‘a’ is ‘1’,
then the bank will be selected as
per the BSR value (default).
Words: 1
Cycles: 1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1 Q2 Q3 Q4
Decode Read
register ‘f’
Process
Data
No
operation
If skip:
Q1 Q2 Q3 Q4
No
operation
No
operation
No
operation
No
operation
If skip and followed by 2-word instruction:
Q1 Q2 Q3 Q4
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
Example:
HERE TSTFSZ CNT
NZERO :
ZERO :
Before Instruction
PC = Address (HERE)
After Instruction
If CNT = 0x00,
PC = Address (ZERO)
If CNT ≠ 0x00,
PC = Address (NZERO)
XORLW Exclusive OR Literal with W
Syntax: [ label ] XORLW k
Operands: 0 ≤ k ≤ 255
Operation: (W) .XOR. k → W
Status Affected: N, Z
Encoding:
0000 1010 kkkk kkkk
Description: The contents of W are XOR’ed
with the 8-bit literal ‘k’. The result
is placed in W.
Words: 1
Cycles: 1
Q Cycle Activity:
Q1 Q2 Q3 Q4
Decode Read
literal ‘k’
Process
Data
Write to W
Example: XORLW 0xAF
Before Instruction
W=0xB5
After Instruction
W = 0x1A