Vault 7: Projects

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© 2005-2011 Microchip Technology Inc. DS70157F-page 189
Section 5. Instruction Descriptions
Instruction
Descriptions
5
COM
Complement f
Implemented in: PIC24F PIC24H PIC24E dsPIC30F dsPIC33F dsPIC33E
X X X X X X
Syntax: {label:} COM{.B} f {,WREG}
Operands: f [0 ... 8191]
Operation: (f)
destination designated by D
Status Affected: N, Z
Encoding: 1110 1110 1BDf ffff ffff ffff
Description: Compute the 1’s complement of the contents of the file register and place
the result in the destination register. The optional WREG operand
determines the destination register. If WREG is specified, the result is
stored in WREG. If WREG is not specified, the result is stored in the file
register.
The ‘B’ bit selects byte or word operation (‘0’ for word, ‘1’ for byte).
The ‘D’ bit selects the destination (‘0’ for WREG, ‘1’ for file register).
The ‘f’ bits select the address of the file register.
Note 1: The extension .B in the instruction denotes a byte operation
rather than a word operation. You may use a .W extension to
denote a word operation, but it is not required.
2: The WREG is set to working register W0.
Words: 1
Cycles:
1
(1)
Note 1:
In dsPIC33E and PIC24E devices, the listed cycle count does not apply to read and
read-modify-write operations on non-CPU Special Function Registers. For more
details, see
Note 3
in
Section 3.2.1 “Multi-Cycle Instructions”
.
Example 1:
COM.b RAM200 ; COM RAM200 (Byte mode)
Before
Instruction
After
Instruction
RAM200 80FF RAM200 8000
SR 0000 SR 0002 (Z)
Example 2:
COM RAM400, WREG ; COM RAM400 and store to WREG
; (Word mode)
Before
Instruction
After
Instruction
WREG 1211 WREG F7DC
RAM400 0823 RAM400 0823
SR 0000 SR 0008 (N = 1)

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