Vault 7: Projects
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© 2005-2011 Microchip Technology Inc. DS70157F-page 423
Section 5. Instruction Descriptions
Instruction
Descriptions
5
SUBR
Subtract Wb from Short Literal
Implemented in: PIC24F PIC24H PIC24E dsPIC30F dsPIC33F dsPIC33E
X X X X X X
Syntax: {label:} SUBR{.B} Wb, #lit5 Wd
[Wd]
[Wd++]
[Wd--]
[++Wd]
[--Wd]
Operands: Wb ∈ [W0 ... W15]
lit5 ∈ [0 ... 31]
Wd ∈ [W0 ... W15]
Operation: lit5 – (Wb) → Wd
Status Affected: DC, N, OV, Z, C
Encoding: 0001 0www wBqq qddd d11k kkkk
Description: Subtract the contents of the base register Wb from the unsigned 5-bit
literal operand, and place the result in the destination register Wd.
Register direct addressing must be used for Wb. Either register direct or
indirect addressing may be used for Wd.
The ‘w’ bits select the address of the base register.
The ‘B’ bit selects byte or word operation (‘0’ for word, ‘1’ for byte).
The ‘q’ bits select the destination Address mode.
The ‘d’ bits select the destination register.
The ‘k’ bits provide the literal operand, a five-bit integer number.
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
Example 1:
SUBR.B W0, #0x10, W1 ; Sub. W0 from 0x10 (Byte mode)
; Store result to W1
Before
Instruction
After
Instruction
W0 F310 W0 F310
W1 786A W1 7800
SR 0000 SR 0103 (DC, Z, C = 1)
Example 2:
SUBR W0, #0x8, [W2++] ; Sub. W0 from 0x8 (Word mode)
; Store result to [W2]
; Post-increment W2
Before
Instruction
After
Instruction
W0 0009 W0 0009
W2 2004 W2 2006
Data 2004 A557 Data 2004 FFFF
SR 0000 SR 0108 (DC, N = 1)
Protego_Release_01_05-Related-OEM-Documentation-PIC24FJ64GA004-Programmers_Reference_Manual.pdf