PIC18LF2X_13 Datasheet, PDF (89/560 Pages) Microchip Technology – PIC18(L)F2X/45K50 USB Flash MCU Product Brief

PIC18(L)F2X/4XK22
5.4.5 STATUS REGISTER
The STATUS register, shown in Register 5-2, contains
the arithmetic status of the ALU. As with any other SFR,
it can be the operand for any instruction.
If the STATUS register is the destination for an instruc-
tion that affects the Z, DC, C, OV or N bits, the results
of the instruction are not written; instead, the STATUS
register is updated according to the instruction per-
formed. Therefore, the result of an instruction with the
STATUS register as its destination may be different
than intended. As an example, CLRF STATUS will set
the Z bit and leave the remaining Status bits
unchanged (‘000u u1uu’).
5.5 Register Definitions: Status
REGISTER 5-2: STATUS: STATUS REGISTER
U-0
—
bit 7
U-0
U-0
R/W-x
—
—
N
It is recommended that only BCF, BSF, SWAPF, MOVFF
and MOVWF instructions are used to alter the STATUS
register, because these instructions do not affect the Z,
C, DC, OV or N bits in the STATUS register.
For other instructions that do not affect Status bits, see
the instruction set summaries in Section 25.2
“Extended Instruction Set” and Table 25-3.
Note:
The C and DC bits operate as the borrow
and digit borrow bits, respectively, in
subtraction.
R/W-x
OV
R/W-x
Z
R/W-x
DC⁽¹⁾
R/W-x
C⁽¹⁾
bit 0
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-5
bit 4
bit 3
bit 2
bit 1
bit 0
Unimplemented: Read as ‘0’
N: Negative bit
This bit is used for signed arithmetic (two’s complement). It indicates whether the result was negative
(ALU MSB = 1).
1 = Result was negative
0 = Result was positive
OV: Overflow bit
This bit is used for signed arithmetic (two’s complement). It indicates an overflow of the 7-bit
magnitude which causes the sign bit (bit 7 of the result) to change state.
1 = Overflow occurred for signed arithmetic (in this arithmetic operation)
0 = No overflow occurred
Z: Zero bit
1 = The result of an arithmetic or logic operation is zero
0 = The result of an arithmetic or logic operation is not zero
DC: Digit Carry/Borrow bit (ADDWF, ADDLW,SUBLW,SUBWF instructions)⁽¹⁾
1 = A carry-out from the 4th low-order bit of the result occurred
0 = No carry-out from the 4th low-order bit of the result
C: Carry/Borrow bit (ADDWF, ADDLW, SUBLW, SUBWF instructions)⁽¹⁾
1 = A carry-out from the Most Significant bit of the result occurred
0 = No carry-out from the Most Significant bit of the result occurred
Note 1: For Borrow, the polarity is reversed. A subtraction is executed by adding the two’s complement of the
second operand. For rotate (RRF, RLF) instructions, this bit is loaded with either the high-order or low-order
bit of the source register.
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DS41412F-page 89