Function 0303 - Allocate Real Mode Callback Address

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- 7.2.24 -

PMODE/W MSDOS Extender

PMODE/W Supported DPMI INT 31h functions

Function 0303 - Allocate Real Mode Callback Address

PMODE/W API

This function Returns a unique real mode segment:offset, known as a "real mode callback", that will transfer control from real mode to a protected mode procedure. Callback addresses obtained with this function can be passed by a protected mode program to a real mode application, interrupt handler, device driver, TSR, etc... so that the real mode program can call procedures within the protected mode program.

In:
   AX     = 0303h
   DS:ESI = selector:offset of protected mode procedure
            to call
   ES:EDI = selector:offset of 32h byte buffer for real
            mode register data structure to be used when
            calling the callback routine.
Out:
   if successful:
     carry flag clear
     CX:DX  = segment:offset of real mode callback
   if failed:
     carry flag set

Notes:
A descriptor may be allocated for each callback to hold the real mode SS descriptor. Real mode callbacks are a limited system resource. A client should release a callback that it is no longer using.


Function 0302 - Call Real Mode Procedure With IRET Frame	Table of Content	Function 0304 - Free Real Mode Callback Address

- 7.2.24 -