Datasheet

© 2009 Microchip Technology Inc. DS40044G-page 127
PIC16F627A/628A/648A
RETLW Return with Literal in W
Syntax: [ label ] RETLW k
Operands: 0 ≤ k ≤ 255
Operation: k → (W);
TOS → PC
Status Affected: None
Encoding:
11 01xx kkkk kkkk
Description: The W register is loaded with
the eight-bit literal ‘k’. The
program counter is loaded from
the top of the stack (the return
address). This is a two-cycle
instruction.
Words: 1
Cycles: 2
Example
TABLE
CALL TABLE;W contains table
;offset value
• ;W now has table value
•
•
ADDWF PC;W = offset
RETLW k1;Begin table
RETLW k2;
•
•
•
RETLW kn; End of table
Before Instruction
W = 0x07
After Instruction
W = value of k8
RETURN Return from Subroutine
Syntax: [ label ] RETURN
Operands: None
Operation: TOS → PC
Status Affected: None
Encoding:
00 0000 0000 1000
Description: Return from subroutine. The
stack is POPed and the top of
the stack (TOS) is loaded into
the program counter. This is a
two-cycle instruction.
Words: 1
Cycles: 2
Example
RETURN
After Interrupt
PC = TOS
RLF Rotate Left f through Carry
Syntax: [ label ] RLF f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: See description below
Status Affected: C
Encoding:
00 1101 dfff ffff
Description: The contents of register ‘f’ are
rotated one bit to the left through
the Carry Flag. If ‘d’ is ‘0’, the
result is placed in the W register.
If ‘d’ is ‘1’, the result is stored
back in register ‘f’.
Words: 1
Cycles: 1
Example
RLF REG1, 0
Before Instruction
REG1=1110 0110
C =0
After Instruction
REG1=1110 0110
W = 1100 1100
C =1
REGISTER FC