dsp56800e Freescale Semiconductor, Inc, dsp56800e Datasheet - Page 464

• Manufacturer Part Number: dsp56800e
• Description: 16-bit Digital Signal Controller Core
• Manufacturer: Freescale Semiconductor, Inc

DECA
Operation:
D – 1 → D
Description: Decrement a value in an AGU pointer register. The full 24-bit value of the pointer register is used when
Usage:
Example:
Explanation of Example:
Condition Codes Affected:
Instruction Fields:
Instruction Opcodes:
Timing:
Memory:
A-120
DECA
Operation
DECA
Before Execution
Rn
R0
decrementing.
This instruction can be used to step backwards through a memory buffer.
DECA
Prior to execution, the R0 register contains $002222. Execution of the DECA R0 instruction causes
the value in R0 to be reduced by one, and the result ($002221) is stored back in R0.
The condition codes are not modified by this instruction.
1 oscillator clock cycle
1 program word
(no parallel move)
Operands
002222
R0
Rn
DSP56800E Core Reference Manual
Decrement AGU Register
15
1
C
1
0
; decrement R0
W
1
0
Assembler Syntax:
DECA
Decrement AGU register by one
12
0
11
0
After Execution
R0
1
0
D
0
8
002221
Comments
7
1
(no parallel move)
0
Freescale Semiconductor
1
1
4
R
3
DECA
0
R
R
0