PIC18F4520ESLASHMLQTP datasheet(306/390 Pages) MICROCHIP

306 / 390 page

PIC18F2420/2520/4420/4520

DS39631A-page 304

Preliminary

 2004 Microchip Technology Inc.

SUBWFB

Subtract W from f with Borrow

Syntax:

SUBWFB

f {,d {,a}}

Operands:

≤ f ≤ 255

∈ [0,1]

Operation:

(f) – (W) – (C)

→ dest

Status Affected:

N, OV, C, DC, Z

Encoding:

0101

10da

ffff

Description:

Subtract W and the CARRY flag

(borrow) from register ‘f’ (2’s comple-

ment method). If ‘d’ is ‘0’, the result is

stored in W. If ‘d’ is ‘1’, the result is

stored back in register ‘f’ (default).

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f

≤ 95 (5Fh). See

Section 24.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words:

Cycles:

Q Cycle Activity:

Decode

Read

Process

Data

Write to

destination

Example 1:

SUBWFB

REG, 1, 0

Before Instruction

REG

19h

(0001 1001)

0Dh

(0000 1101)

After Instruction

REG

0Ch

(0000 1011)

0Dh

(0000 1101)

; result is positive

Example 2:

SUBWFB

REG, 0, 0

Before Instruction

REG

1Bh

(0001 1011)

1Ah

(0001 1010)

After Instruction

REG

1Bh

(0001 1011)

00h

; result is zero

Example 3:

SUBWFB

REG, 1, 0

Before Instruction

REG

03h

(0000 0011)

0Eh

(0000 1101)

After Instruction

REG

F5h

(1111 0100)

; [2’s comp]

0Eh

(0000 1101)

; result is negative

SWAPF

Swap f

Syntax:

SWAPF f {,d {,a}}

Operands:

≤ f ≤ 255

∈ [0,1]

Operation:

(f<3:0>)

→ dest<7:4>,

(f<7:4>)

→ dest<3:0>

Status Affected:

None

Encoding:

0011

10da

ffff

Description:

The upper and lower nibbles of register

‘f’ are exchanged. If ‘d’ is ‘0’, the result

is placed in W. If ‘d’ is ‘1’, the result is

placed in register ‘f’ (default).

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f

≤ 95 (5Fh). See

Section 24.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words:

Cycles:

Q Cycle Activity:

Decode

Read

Process

Data

Write to

destination

Example:

SWAPF

REG, 1, 0

Before Instruction

REG

53h

After Instruction

REG

35h

PIC18F4520E/MLQTP Datasheet(PDF) 306 Page - Microchip Technology

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