MFSH_PHYSTOVIRT - Convert physical to virtual adress

Purpose

Translate the physical address of a data buffer into a virtual address.

Calling Sequence

int far pascal MFSH_PHYSTOVIRT(ulAddr, usLen, pusSel) unsigned long ulAddr; unsigned short usLen; unsigned short far * pusSel;

Where

ulAddr is the physical address to be translated.

usLen is the length of the segment for the physical address.

pusSel is a pointer to the word in which the selector or segment is returned.

Returns

If an error is not detected, a zero error code is returned. If an error is detected, the following error is returned:

ERROR_PROTECTION_VIOLATION – the supplied address is invalid.

Remarks

This helper is for use by a mini-FSD with an imbedded device driver. It is the same as the standard device driver helper PHYSTOVIRT. A segment/offset pair is returned in real mode for addresses below the 1-Meg boundary. Else a selector/offset pair is returned.

A caller must issue a corresponding UNPHYSTOVIRT before returning to its caller or using any other helpers.