Samsung S3C9228/P9228, 8-Bit CMOS Microcontroller user manual RET Return, Operation PC ¨ @SP

SAM88RI INSTRUCTION SET S3C9228/P9228

RET — Return

RET

Operation: PC ¨ @SP

SP ¨ SP + 2

The RET instruction is normally used to return to the previously executing procedure at the end of a procedure entered by a CALL instruction. The contents of the location addressed by the stack pointer are popped into the program counter. The next statement that is executed is the one that is addressed by the new program counter value.

Flags: No flags are affected.

Format:

Bytes Cycles Opcode (Hex)

opc

1 8 AF

Example: Given: SP = 0BCH, (SP) = 101AH, and PC = 1234:

RET → PC = 101AH, SP = 0BEH

The statement "RET" pops the contents of stack pointer location 0BCH (10H) into the high byte of the program counter. The stack pointer then pops the value in location 0BDH (1AH) into the PC's low byte and the instruction at location 101AH is executed. The stack pointer now points to memory location 0BEH.

6-38