PIC18F8520-IPT301 View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC18F8520-IPT301

64/80-Pin High-Performance, 256 Kbit to 1 MbitEnhanced Flash Microcontrollers with A/D

Microchip Technology 

PIC18F6520/8520/6620/8620/6720/8720

SUBWFB

Subtract W from f with Borrow

Syntax:

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

Operands:

0  f  255

d  [0,1]

a  [0,1]

Operation:

(f) – (W) – (C) dest

Status Affected: N, OV, C, DC, Z

Encoding:

0101 10da ffff ffff

Description:

Subtract W and the Carry flag

(borrow) from register ‘f’ (2’s com-

plement 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).

Words:

1

Cycles:

1

Q Cycle Activity:

Q1

Q2

Decode

Read

register ‘f’

Q3

Process

Data

Q4

Write to

destination

Example 1:

SUBWFB REG, 1, 0

Before Instruction

REG

W

C

= 0x19

= 0x0D

=1

After Instruction

REG

W

C

Z

N

= 0x0C

= 0x0D

=1

=0

=0

(0001 1001)

(0000 1101)

(0000 1011)

(0000 1101)

; result is positive

Example 2:

SUBWFB REG, 0, 0

Before Instruction

REG

W

C

= 0x1B

= 0x1A

=0

After Instruction

REG

W

C

Z

N

= 0x1B

= 0x00

=1

=1

=0

(0001 1011)

(0001 1010)

(0001 1011)

; result is zero

Example 3:

SUBWFB REG, 1, 0

Before Instruction

REG

W

C

= 0x03

= 0x0E

=1

After Instruction

REG = 0xF5

W

= 0x0E

C

=0

Z

=0

N

=1

(0000 0011)

(0000 1101)

(1111 0100)

; [2’s comp]

(0000 1101)

; result is negative

SWAPF

Swap f

Syntax:

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

Operands:

0  f  255

d  [0,1]

a  [0,1]

Operation:

(f<3:0>)  dest<7:4>,

(f<7:4>)  dest<3:0>

Status Affected: None

Encoding:

0011 10da ffff 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 will be selected, overriding

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

bank will be selected as per the

BSR value (default).

Words:

1

Cycles:

1

Q Cycle Activity:

Q1

Q2

Decode

Read

register ‘f’

Q3

Process

Data

Q4

Write to

destination

Example:

SWAPF REG, 1, 0

Before Instruction

REG = 0x53

After Instruction

REG = 0x35

DS39609C-page 296

 2003-2013 Microchip Technology Inc.

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