[Register(16:31)] ← [Register(0:15)];
[Register(0:15)] ← [Register(16:31]
SWAP DnSize word
Exchange the upper and lower 16-bit words of a data register.
The SWAP Dn instruction enables the higher-order word in a register to take part in word operations by moving it into the lower-order position. SWAP Dn is effectively equivalent to ROR.L Di,Dn, where [Di] = 16. However, SWAP clears the C-bit of the CCR, whereas ROR sets it according to the last bit to be shifted into the carry bit.
| X | N | Z | V | C |
|---|---|---|---|---|
| - | * | * | 0 | 0 |
The N-bit is set if most-significant bit of the 32-bit result is set and cleared otherwise. The Z-bit is set if 32-bit result is zero and cleared otherwise.
From MOTOROLA M68000 FAMILY Programmer's reference manual. Copyright 1992 by Motorola Inc./NXP. Adapted with permission.