Vault 7: Projects

This publication series is about specific projects related to the Vault 7 main publication.

© 2005-2011 Microchip Technology Inc. DS70157F-page 405
Section 5. Instruction Descriptions
Instruction
Descriptions
5
SUB
Subtract WREG from f
Implemented in: PIC24F PIC24H PIC24E dsPIC30F dsPIC33F dsPIC33E
X X X X X X
Syntax: {label:} SUB{.B} f {,WREG}
Operands: f [0 ... 8191]
Operation: (f) – (WREG) destination designated by D
Status Affected: DC, N, OV, Z, C
Encoding: 1011 0101 0BDf ffff ffff ffff
Description: Subtract the contents of the default working register WREG from the
contents of the specified 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:
SUB.B 0x1FFF ; Sub. WREG from (0x1FFF) (Byte mode)
; Store result to 0x1FFF
Before
Instruction
After
Instruction
WREG (W0) 7804 WREG (W0) 7804
Data 1FFE 9439 Data 1FFE 9039
SR 0000 SR 0001 (C = 1)
Example 2:
SUB 0xA04, WREG ; Sub. WREG from (0xA04) (Word mode)
; Store result to WREG
Before
Instruction
After
Instruction
WREG (W0) 6234 WREG (W0) E2EF
Data 0A04 4523 Data 0A04 4523
SR 0000 SR 0008 (N = 1)

e-Highlighter

Click to send permalink to address bar, or right-click to copy permalink.

Un-highlight all Un-highlight selectionu Highlight selectionh