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No operation (prefix), Status and conditions changed by instruction, Example – Freescale Semiconductor StarCore SC140 User Manual

Page 647

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NOP

SC140 DSP Core Reference Manual

A-333

NOP

No Operation (PREFIX)

NOP

Description

Status and conditions that Affect Instruction

None.

Status and Conditions Changed by Instruction

None.

Example

nop

Instruction Formats and Opcodes

Operation

Assembler Syntax

no operation

NOP

NOP

This instruction is encoded as a one-word prefix inside the set, or alone. If the NOP is the only instruction
in the execution set, it takes one cycle to execute although no operation is done. This is useful in case
delays are needed in a program for various reasons (for example, to account for pipeline delays). The NOP
instruction is not dispatched to any execution unit. As a prefix, it is identified by the dispatcher and is not
dispatched further.

If grouped with other instructions (as an intra-group NOP), it functions as a program place-holder.

In a few isolated cases, the assembler adds this instruction inside an execution set to help arrange the
instructions within that set for proper dispatching. These cases are implementation-dependent. The
assembler issues a warning to make the user aware of the event.

Instruction

Words Cycles Type

Opcode

15

8

7

0

NOP

1

1

4

1

0

0

1

0

0

0

0

1

1

0

0

0

0

0

0