Motorola 24-Bit Digital Signal Processor manual Return from Interrupt, Operation Assembler Syntax

INSTRUCTION DESCRIPTIONS

	RTI	Return from Interrupt		RTI
Operation:			Assembler Syntax:
	SSH ➞ PC; SSL ➞ SR; SP–1 ➞ SP		RTI

Description: Pull the program counter (PC) and the status register (SR) from the system stack. The previous program counter and status register are lost.

Restrictions: Due to pipelining in the program controller and the fact that the RTI instruction accesses certain program controller registers, the RTI instruction must not be

immediately preceded by any of the following instructions:

Immediately before RTI MOVEC to SR, SSH, SSL, or SP

MOVEM to SR, SSH, SSL, or SP

MOVEP to SR, SSH, SSL, or SP

MOVEC from SSH

MOVEM from SSH

MOVEP from SSH

ANDI MR or ANDI CCR

ORI MR or ORI CCR

An RTI instruction cannot be the last instruction in a DO loop (at LA).

An RTI instruction cannot be repeated using the REP instruction.

Example:

	:
RTI	;pull PC and SR from system stack
	:

Explanation of Example: The RTI instruction pulls the 16-bit program counter (PC) and the 16-bit status register (SR) from the system stack and updates the system stack pointer (SP).

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