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16-bit MCU and DSC Programmer’s Reference Manual
DS70157F-page 194 © 2005-2011 Microchip Technology Inc.
CP
Compare Wb with Ws, Set Status Flags
Implemented in: PIC24F PIC24H PIC24E dsPIC30F dsPIC33F dsPIC33E
X X X X X X
Syntax: {label:} CP{.B} Wb, Ws
[Ws]
[Ws++]
[Ws--]
[++Ws]
[--Ws]
Operands: Wb ∈ [W0 ... W15]
Ws ∈ [W0 ... W15]
Operation: (Wb) – (Ws)
Status Affected: DC, N, OV, Z, C
Encoding: 1110 0001 0www wB00 0ppp ssss
Description: Compute (Wb) – (Ws), and update the STATUS register. This instruction is
equivalent to the SUB instruction, but the result of the subtraction is not
stored. Register direct addressing must be used for Wb. Register direct or
indirect addressing may be used for Ws.
The ‘w’ bits select the address of the Wb source register.
The ‘B’ bit selects byte or word operation (‘0’ for word, ‘1’ for byte).
The ‘p’ bits select the source Address mode.
The ‘s’ bits select the address of the Ws source register.
Note: 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.
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:
CP.B W0, [W1++] ; Compare [W1] with W0 (Byte mode)
; Post-increment W1
Before
Instruction
After
Instruction
W0 ABA9 W0 ABA9
W1 2000 W1 2001
Data 2000 D004 Data 2000 D004
SR 0000 SR 0009 (N, C = 1)
Protego_Release_01_05-Related-OEM-Documentation-PIC24FJ64GA004-Programmers_Reference_Manual.pdf