EDE
EDE+254
TONI
TONI+254
Instruction Set Description
177
SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
CPUX
4.6.2.17 DEC
* DEC[.W]
Decrement destination
* DEC.B
Decrement destination
Syntax
DEC dst
or
DEC.W dst
DEC.B dst
Operation
dst – 1
→
dst
Emulation
SUB #1,dst
SUB.B #1,dst
Description
The destination operand is decremented by 1. 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.
Set if initial value of destination was 08000h, otherwise reset.
Set if initial value of destination was 080h, otherwise reset.
Mode Bits
OSCOFF, CPUOFF, and GIE are not affected.
Example
R10 is decremented by 1.
DEC
R10
; Decrement R10
; Move a block of 255 bytes from memory location starting with EDE to
; memory location starting with TONI. Tables should not overlap: start of
; destination address TONI must not be within the range EDE to EDE+0FEh
MOV
#EDE,R6
MOV
#255,R10
L$1
MOV.B
@R6+,TONI-EDE-1(R6)
DEC
R10
JNZ
L$1
Do not transfer tables using the routine above with the overlap shown in
Figure 4-36. Decrement Overlap