Function 0305 - Get State Save/Restore Addresses

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- 7.2.26 -

PMODE/W MSDOS Extender

PMODE/W Supported DPMI INT 31h functions

Function 0305 - Get State Save/Restore Addresses

PMODE/W API

This function Returns the address of two procedures used to save and restore the state of the current task's registers in the mode (protected or real) which is not currently executing.

In:
   AX     = 0305h
Out:
   always successful:
     carry flag clear
     AX     = size of buffer in bytes required to save state
     BX:CX  = segment:offset of real mode routine used
              to save/restore state
     SI:EDI = selector:offset of protected mode routine
              used to save/restore state

Notes:
The real mode segment:offset returned by this function should be called only in real mode to save/restore the state of the protected mode register. The protected mode selector:offset returned by this function should be called only in protected mode to save/restore the state of the real mode registers.

Both of the state save/restore procedures are entered by a FAR CALL with the following parameters:

   AL       = 0 to save state
            = 1 to restore state
   ES:(E)DI = (selector or segment):offset of state buffer

The state buffer must be at least as large as the value returned in AX by INT 31h function 0305h. The state save/restore procedures do not modify an registers. DI must be used for the buffer offset in real mode, EDI must be used in protected mode.

Some DPMI hosts and VCPI/XMS/raw will not require the state to be saved, indicating this by returning a buffer size of zero in AX. In such cases, that addresses returned by this function can still be called, although the will simply return without performing any useful function.

Clients do not need to call the state save/restore procedures before using INT 31h function 0300h, 0301h, or 0302h. The state save/restore procedures are provided for clients that use the raw mode switch services only.


Function 0304 - Free Real Mode Callback Address	Table of Content	Function 0306 - Get Raw Mode Switch Addresses

- 7.2.26 -