18.3.2.5 Virtual Ports
The Virtual PORT registers map the most frequently used regular PORT registers into the I/O
Register space with single-cycle bit access. Access to the Virtual
PORT registers has the same outcome as access to the ordinary registers allowing for
memory-specific instructions, such as bit manipulation instructions, which cannot be
used in the extended I/O Register space where the regular PORT registers reside.
The following table shows the mapping between the
PORT and VPORT registers.
| Regular PORT Register | Mapped to Virtual PORT Register |
|---|---|
| PORTx.DIR | VPORTx.DIR |
| PORTx.OUT | VPORTx.OUT |
| PORTx.IN | VPORTx.IN |
| PORTx.INTFLAGS | VPORTx.INTFLAGS |
Note: Avoid accessing the mapped VPORT register using the single-cycle I/O instructions
immediately after accessing the regular PORT register. This may cause a memory collision
since the single-cycle I/O access to VPORT is faster than the regular PORT register access.