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S3C84E5/C84E9/P84E9 INSTRUCTION SET
6-83
SWAP — Swap Nibbles
SWAP dst
Operation: dst (0 – 3) ↔ dst (4 – 7)
The contents of the lower four bits and the upper four bits of the destination operand are swapped.
7 04 3
Flags: C: Undefined.
Z: Set if the result is "0"; cleared otherwise.
S: Set if the result bit 7 is set; cleared otherwise.
V: Undefined.
D: Unaffected.
H: Unaffected.
Format:
Bytes Cycles Opcode
(Hex)
Addr Mode
dst
opc dst 2 4 F0 R
4 F1 IR
Examples: Given: Register 00H = 3EH, register 02H = 03H, and register 03H = 0A4H:
SWAP 00H → Register 00H = 0E3H
SWAP @02H → Register 02H = 03H, register 03H = 4AH
In the first example, if the general register 00H contains the value 3EH (00111110B), the statement
"SWAP 00H" swaps the lower and the upper four bits (nibbles) in the 00H register, leaving the value
0E3H (11100011B).