Samsung S3C84I8 User Manual page 177

S3C84I8/F84I8/C84I9/F84I9
ENTER
— Enter
ENTER
SP ← SP – 2
Operation:
@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.
No flags are affected.
Flags:
Format:
opc
The diagram below shows an example of how to use an ENTER statement.
Example:
Address Data
IP 0050
PC 0040
0022
22 Data
Stack
Before
Address
40
Enter
41
Address H
42
Address L
43
Address H
Memory
Bytes
1
Address
IP 0043
Data
PC 0110
1F
01
10
0020
20 IPH
21 IPL
22 Data
Stack
INSTRUCTION SET
Cycles Opcode
(Hex)
14 1F
After
Data
Address
40
Enter
41
Address H
42
Address L
43
Address H
110
Routine
00
50
Memory
Data
1F
01
10
6-41