Samsung S3F80JB manual Enter Enter, Operation SP, @Sp @Ip, Format Bytes Cycles Opcode Hex

S3F80JBINSTRUCTION SET

ENTER — Enter

ENTER
Operation: SP	←	SP – 2
@SP	←	IP
IP	←	PC
PC	←	@IP
IP	←	IP + 2

This instruction is useful when implementing threaded-code languages. The contents of the instruction pointer are pushed to the stack. The program counter (PC) value is then written to the instruction pointer. The program memory word that is pointed to by the instruction pointer is loaded into the PC, and the instruction pointer is incremented by two.

Flags: No flags are affected.

Format:

Bytes Cycles Opcode (Hex)

opc

1 14 1F

Example: The diagram below shows one example of how to use an ENTER statement.

Address

IP

PC

SP

22

0050

0040

0022

Data

Stack

Before						After
Data			Address		Data
			IP	0043
Address		Data				Address		Data
40	Enter	1F	PC	0110		40	Enter	1F
41	Address H	01				41	Address H	01
42	Address L	10				42	Address L	10
43	Address H		SP	0020		43	Address H
			20	IPH	00	110	Routine
	Memory		21	IPL	50		Memory
			22	Data
				Stack

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