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Instruction Set Description
4.6.3.13 DECDX
* DECDX.A
Double-decrement destination address-word
* DECDX.[W]
Double-decrement destination word
* DECDX.B
Double-decrement destination byte
DECDX.A dst
Syntax
DECDX dst
or
DECDX.W dst
DECDX.B dst
Operation
dst – 2
→
dst
SUBX.A #2,dst
Emulation
SUBX #2,dst
SUBX.B #2,dst
Description
The destination operand is decremented by two. The original contents are lost.
Status Bits
N:
Set if result is negative, reset if positive
Z:
Set if dst contained 2, reset otherwise
C:
Reset if dst contained 0 or 1, set otherwise
V:
Set if an arithmetic overflow occurs, otherwise reset
Mode Bits
OSCOFF, CPUOFF, and GIE are not affected.
Example
RAM address-word TONI is decremented by two.
DECDX.A
TONI
; Decrement TONI
198
CPUX
SLAU272C – May 2011 – Revised November 2013
Copyright © 2011–2013, Texas Instruments Incorporated