VioGetPhysBuf

Bindings: C, MASM

This call gets addressability to the physical display buffer.

VioGetPhysBuf (DisplayBuf, Reserved)

DisplayBuf(PVIOPHYSBUF) - input/output Address of the data structure that contains the physical display buffer address and length on input and returns the selectors used to address the display buffer.

displaybufaddr (PBYTE) Address of the 32 bit start address (selector:offset) of the physical display buffer passed as input. If displaybuflen is 0, then displaybufaddr is the far address of the PhysBuf Block described below.

displaybuflen (ULONG) 32 bit length of the physical display buffer. If displaybuflen is 0, then displaybufaddr is treated as the far address of the PhysBuf Block described below and the Selector List is not present.

selectors (SEL) Selector list.

Returns the selectors (each of word-length) that address the physical display buffer. The first selector returned in the list, addresses the first 64KB of the physical display buffer or displaybuflen, whichever is smaller. If displaybuflen is greater than 64KB, the second selector addresses the second 64KB.

The last selector returned in the list, addresses the remainder of the display buffer. The application is responsible for ensuring enough space is reserved for the selector list to accommodate the specified buffer length.

PhysBuf Block (PhysBuf) Address of the data structure. The PhysBuf Block is a variable length data structure. The first word is the Length of the PhysBuf Block in bytes. The remaining words of the structure are the selectors that address the physical video buffer. If Length is specified as 2, the required length of the PhysBuf Block is returned in its place.

PhysBuf Block (USHORT) Length of PhysBuf structure in bytes

selector (SEL) First selector

selector (SEL) Next selector

selector (SEL) … …

selector (SEL) Last selector

Reserved (USHORT) - input Reserved word of 0s.

rc (USHORT) - return Return code descriptions are:

0	NO_ERROR
350	ERROR_VIO_PTR
429	ERROR_VIO_IN_BG
430	ERROR_VIO_ILLEGAL_DURING_POPUP
436	ERROR_VIO_INVALID_HANDLE
465	ERROR_VIO_DETACHED
494	ERROR_VIO_EXTENDED_SG

Remarks

If displaybuflen = 0, VioGetPhysBuf returns a selector that addresses the physical display buffer corresponding to the current mode. One selector is returned in Selector List. If a VioGetPhysBuf is issued after a VioGetBuf, then all VioWrtXX calls will on longer be written to the LVB. They will only be written to the physical display buffer. An application uses VioGetPhysBuf to get addressability to the physical display buffer. The selector returned by VioGetPhysBuf may be used only when an application program is executing in the foreground. When an application wants to access the physical display buffer, the application must call VioScrLock. VioScrLock either waits until the program is running in the foreground or returns a warning when the program is running in the background. For more information refer to VioScrLock and VioScrUnLock.

The buffer range specified for the physical screen buffer must fall between hex 'A0000' and 'BFFFF' inclusive. An application may issue VioGetPhysBuf only when it is running in the foreground. An application may issue VioGetPhysBuf more than once.