PIC18F25J11-I/PT MICROCHIP [Microchip Technology], PIC18F25J11-I/PT Datasheet - Page 93

• Manufacturer Part Number: PIC18F25J11-I/PT
• Description: 28/44-Pin, Low-Power, High-Performance Microcontrollers with nanoWatt XLP Technology
• Manufacturer: MICROCHIP [Microchip Technology]

5.6.1
Enabling the PIC18 extended instruction set changes
the behavior of Indirect Addressing using the FSR2
register pair and its associated file operands. Under
proper conditions, instructions that use the Access
Bank, that is, most bit and byte-oriented instructions,
can invoke a form of Indexed Addressing using an
offset specified in the instruction. This special address-
ing mode is known as Indexed Addressing with Literal
Offset, or Indexed Literal Offset mode.
When using the extended instruction set, this
addressing mode requires the following:
• The use of the Access Bank is forced (‘a’ = 0);
• The file address argument is less than or equal to
Under these conditions, the file address of the
instruction is not interpreted as the lower byte of an
address (used with the BSR in Direct Addressing) or as
an 8-bit address in the Access Bank. Instead, the value
is interpreted as an offset value to an Address Pointer
specified by FSR2. The offset and the contents of
FSR2 are added to obtain the target address of the
operation.
© 2009 Microchip Technology Inc.
and
5Fh.
INDEXED ADDRESSING WITH
LITERAL OFFSET
PIC18F46J11 FAMILY
5.6.2
Any of the core PIC18 instructions that can use Direct
Addressing are potentially affected by the Indexed
Literal Offset Addressing mode. This includes all byte
and bit-oriented instructions, or almost one-half of the
standard PIC18 instruction set. Instructions that only
use Inherent or Literal Addressing modes are
unaffected.
Additionally, byte and bit-oriented instructions are not
affected if they use the Access Bank (Access RAM bit is
‘1’) or include a file address of 60h or above. Instructions
meeting these criteria will continue to execute as before.
A comparison of the different possible addressing
modes when the extended instruction set is enabled is
provided in Figure 5-9.
Those who desire to use byte or bit-oriented instruc-
tions in the Indexed Literal Offset mode should note the
changes to assembler syntax for this mode. This is
described in more detail in Section 26.2.1 “Extended
Instruction Syntax”.
INSTRUCTIONS AFFECTED BY
INDEXED LITERAL OFFSET MODE
DS39932C-page 93