INSTRUCTION DESCRIPTIONS

ROL

Rotate Left

ROL

 

47

24

Operation:

C

(parallel move)

Assembler Syntax: ROL D (parallel move)

Description: Rotate bits 47–24 of the destination operand D one bit to the left and store the result in the destination accumulator. Prior to instruction execution, bit 47 of D is shifted into the carry bit C, and, prior to instruction execution, the value in the carry bit C is shifted into bit 24 of the destination accumulator D. This instruction is a 24-bit opera- tion. The remaining bits of the destination operand D are not affected.

Example:

:

ROL A1 #314,N2 ;rotate A1 one left bit, update N2

:

A

Before Execution

$00:000000:000000

A

After Execution

$00:000001:000000

SR

$0301

SR

$0300

Explanation of Example: Prior to execution, the 56-bit A accumulator contains the value $00:000000:000000. The execution of the ROL A instruction shifts the 24-bit value in the A1 register one bit to the left, shifting bit 47 into the carry bit C, rotating the carry bit C into bit 24, and storing the result back in the A1 register.

A - 262

INSTRUCTION SET DETAILS

MOTOROLA

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Motorola 24-Bit Digital Signal Processor, DSP56000 manual Rotate Left, Operation