Datasheet

PIC18F1220/1320
DS39605F-page 204 © 2007 Microchip Technology Inc.
BTFSC Bit Test File, Skip if Clear
Syntax: [ label ] BTFSC f,b[,a]
Operands: 0 ≤ f ≤ 255
0 ≤ b ≤ 7
a ∈ [0,1]
Operation: skip if (f<b>) = 0
Status Affected: None
Encoding:
1011 bbba ffff ffff
Description: If bit ‘b’ in register ‘f’ is ‘0’, then the
next instruction is skipped.
If bit ‘b’ is ‘0’, then the next
instruction fetched during the current
instruction execution is discarded
and a NOP is executed instead,
making this a two-cycle instruction. 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(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
FALSE
TRUE
BTFSC
:
:
FLAG, 1
Before Instruction
PC = address (HERE)
After Instruction
If FLAG<1> = 0;
PC = address (TRUE)
If FLAG<1> = 1;
PC = address (FALSE)
BTFSS Bit Test File, Skip if Set
Syntax: [ label ] BTFSS f,b[,a]
Operands: 0 ≤ f ≤ 255
0 ≤ b < 7
a ∈ [0,1]
Operation: skip if (f<b>) = 1
Status Affected: None
Encoding:
1010 bbba ffff ffff
Description: If bit ‘b’ in register ‘f’ is ‘1’, then the
next instruction is skipped.
If bit ‘b’ is ‘1’, then the next
instruction fetched during the current
instruction execution is discarded
and a NOP is executed instead,
making this a two-cycle instruction. 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(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
FALSE
TRUE
BTFSS
:
:
FLAG, 1
Before Instruction
PC = address (HERE)
After Instruction
If FLAG<1> = 0;
PC = address (FALSE)
If FLAG<1> = 1;
PC = address (TRUE)