Datasheet

PIC18FXX2
DS39564C-page 224 © 2006 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, over-
riding 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, 0
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 instruc-
tion 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, over-
riding 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, 0
Before Instruction
PC = address (HERE)
After Instruction
If FLAG<1> = 0;
PC = address (FALSE)
If FLAG<1> = 1;
PC = address (TRUE)