Samsung S3C84E5 user manual Enter Enter

S3C84E5/C84E9/P84E9 INSTRUCTION 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 141F

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

		Before					After
Address		Data			Address		Data
IP	0050				IP	0043
		Address		Data			Address		Data
PC	0040	40	Enter	1F	PC	0110	40	Enter	1F
		41	Address H	01			41	Address H	01
		42	Address L	10			42	Address L	10
	0022	43	Address H			0020	43	Address H
					20	IPH	110	Routine
							00
			Memory		21	IPL	50	Memory
22	Data				22	Data
	Stack					Stack

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