INSTRUCTION DESCRIPTIONS
A - 268 INSTRUCTION SET DETAILS
MOTOROLA
Operation: Assembler Syntax:
SSH
âžž
PC; SP–1
âžž
SP RTS
Description:
Pull the program counter (PC) from the system stack. The previous pro-
gram counter is lost. The status register (SR) is not affected.
Restrictions:
Due to pipelining in the program controller and the fact that the RTS
instruction accesses certain controller registers, the RTS instruction must not be immedi-
ately preceded by any of the following instructions:
Immediately before RTS
MOVEC to SSH, SSL, or SP
MOVEM to SSH, SSL, or SP
MOVEP to SSH, SSL, or SP
MOVEC from SSH
MOVEM from SSH
MOVEP from SSH
An RTS instruction cannot be the
last
instruction in a DO loop (at LA).
An RTS instruction cannot be repeated using the REP instruction.
Example:
:
RTS ;pull PC from system stack
:
Explanation of Example:
The RTS instruction pulls the 16-bit program counter (PC)
from the system stack and updates the system stack pointer (SP).
Condition Codes:
The condition codes are not affected by this instruction.
RTS Return from Subroutine RTS
MR CCR
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
LF DM T ** S1 S0 I1 I0 S L E U N Z V C