PIC18F258-I/SP View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC18F258-I/SP

28/40-Pin High-Performance, Enhanced Flash Microcontrollers with CAN Module

Microchip Technology 

PIC18FXX8

SUBWFB

Subtract W from f with Borrow

Syntax:

Operands:

Operation:

Status Affected:

Encoding:

Description:

Words:

Cycles:

Q Cycle Activity:

Q1

Decode

[ label ] SUBWFB f [,d [,a]]

0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

(f) – (W) – (C) → dest

N, OV, C, DC, Z

0101 10da ffff ffff

Subtract W and the Carry flag (borrow)

from register ‘f’ (2’s complement

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 will be selected,

overriding the BSR value. If ‘a’ is ‘1’,

then the bank will be selected as per the

BSR value (default).

1

1

Q2

Read

register ‘f’

Q3

Process

Data

Q4

Write to

destination

Example 1:

SUBWFB REG, 1, 0

Before Instruction

REG =

W

=

C

=

After Instruction

REG =

W

=

C

=

Z

=

N

=

0x19

0x0D

0x01

0x0C

0x0D

0x01

0x00

0x00

(0001 1001)

(0000 1101)

(0000 1011)

(0000 1101)

; result is positive

Example 2:

SUBWFB REG, 0, 0

Before Instruction

REG =

W

=

C

=

After Instruction

REG =

W

=

C

=

Z

=

N

=

0x1B

0x1A

0x00

0x1B

0x00

0x01

0x01

0x00

(0001 1011)

(0001 1010)

(0001 1011)

; result is zero

Example 3:

SUBWFB REG, 1, 0

Before Instruction

REG =

W

=

C

=

After Instruction

REG =

0x03

0x0E

0x01

0xF5

W

= 0x0E

C

= 0x00

Z

= 0x00

N

= 0x01

(0000 0011)

(0000 1101)

(1111 0100)

; [2’s comp]

(0000 1101)

; result is negative

SWAPF

Syntax:

Operands:

Operation:

Status Affected:

Encoding:

Description:

Words:

Cycles:

Q Cycle Activity:

Q1

Decode

Swap f

[ label ] SWAPF f [,d [,a]]

0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

(f<3:0>) → dest<7:4>,

(f<7:4>) → dest<3:0>

None

0011 10da ffff ffff

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 will be selected,

overriding the BSR value. If ‘a’ is ‘1’,

then the bank will be selected as per

the BSR value (default).

1

1

Q2

Read

register ‘f’

Q3

Process

Data

Q4

Write to

destination

Example:

SWAPF REG

Before Instruction

REG =

After Instruction

REG =

0x53

0x35

DS41159E-page 318

© 2006 Microchip Technology Inc.

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