Intel 8XC251SA, User Manual

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A-61
INSTRUCTION SET REFERENCE
EJMP @DRk
Binary Mode Source Mode
Bytes: 3 2
States: 7 6
Hex Code in: Binary Mode = [A5] [Encoding]
Source Mode = [Encoding]
Operation: EJMP
(PC)
←
((DRk))
ERET
Function: Extended return
Description: Pops byte 2, byte 1, and byte 0 of the 3-byte PC successively from the stack and
decrements the stack pointer by 3. Program execution continues at the resulting address,
which normally is the instruction immediately following ECALL.
Flags: No flags are affected.
Example: The stack pointer contains 0BH. On-chip RAM locations 08H, 09H and 0AH contain 01H,
23H and 49H, respectively. After executing the instruction
ERET
the stack pointer contains 08H and program execution continues at location 012349H.
Binary Mode Source Mode
Bytes: 3 2
States: 10 9
Hex Code in: Binary Mode = [A5][Encoding]
Source Mode = [Encoding]
Operation:
ERET
(PC.23:16) ¨ ((SP))
(SP) ¨ (SP) – 1
(PC.15:8) ¨ ((SP))
(SP) ¨ (SP) – 1
(PC.7:0)
←
((SP))
(SP)
←
(SP) – 1
INC <Byte>
Function: Increment
Description: Increments the specified byte variable by 1. An original value of FFH overflows to 00H.
Three addressing modes are allowed for 8-bit operands: register, direct, or register-indirect.
Note: When this instruction is used to modify an output port, the value used as the original
port data is read from the output data latch, not the input pins.
[Encoding] 1 0 0 0 1 0 0 1 u u u u
[Encoding] 1 0 1 0 1 0 1 0