INSTRUCTION DESCRIPTIONS

ASR

Arithmetic Shift Accumulator Right

ASR

55 47

Operation:

230

C (parallel move)

Assembler Syntax:

ASR D (parallel move)

Description: Arithmetically shift the destination operand D one bit to the right and store the result in the destination accumulator. The LS bit of D prior to instruction execution is shifted into the carry bit C, and the MS bit of D is held constant.

Example:

:

ASR B X:–(R3),R3 ;divide B by 2, update R3, load R3

:

B

Before Execution

$A8:A86420:A86421

B

After Execution

$D4:543210:543210

SR

$0300

SR

$0329

Explanation of Example: Prior to execution, the 56-bit B accumulator contains the value $A8:A86420:A86421. The execution of the ASR B instruction shifts the 56-bit value in the B accumulator one bit to the right and stores the result back in the B accu- mulator.

A - 38

INSTRUCTION SET DETAILS

MOTOROLA

Page 307
Image 307
Motorola 24-Bit Digital Signal Processor, DSP56000 manual Arithmetic Shift Accumulator Right