41.1 Read-Modify-Write Operations

Any instruction that specifies a file register as part of the instruction performs a Read-Modify-Write (RMW) operation. The register is read, the data is modified, and the result is stored according to either the Working (W) register or the originating file register, depending on the state of the destination designator ‘d’ (see Table 41-1 for more information). A read operation is performed on a register even if the instruction writes to that register.

Table 41-1. Opcode Field Descriptions
Field	Description
f	Register file address (`0x00` to `0x7F`)
W	Working register (accumulator)
b	Bit address within an 8-bit file register
k	Literal field, constant data or label
x	“Don’t care” location (= `0` or `1`). The assembler will generate code with x = `0`. It is the recommended form of use for compatibility with all Microchip software tools.
d	Destination select; d = `0`: store result in W, d = `1`: store result in file register f.
n	FSR or INDF number. (0-1)
mm	Pre/post increment/decrement mode selection

Table 41-2. Abbreviation Descriptions
Field	Description
PC	Program Counter
TO	Time-Out bit
C	Carry bit
DC	Digit Carry bit
Z	Zero bit
PD	Power-Down bit