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Instruction Set Description
4.6.3.12 DECX
* DECX.A
Decrement destination address-word
* DECX.[W]
Decrement destination word
* DECX.B
Decrement destination byte
DECX.A dst
Syntax
DECX dst
or
DECX.W dst
DECX.B dst
Operation
dst – 1
→
dst
SUBX.A #1,dst
Emulation
SUBX #1,dst
SUBX.B #1,dst
Description
The destination operand is decremented by one. The original contents are lost.
Status Bits
N:
Set if result is negative, reset if positive
Z:
Set if dst contained 1, reset otherwise
C:
Reset if dst contained 0, 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 one.
DECX.A
TONI
; Decrement TONI
197
SLAU272C – May 2011 – Revised November 2013
CPUX
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