MFSH_PHYSTOVIRT - Convert physical to virtual address

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: 

oERROR_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.