INT 31 P - DPMI 0.9+ - GET RAW MODE SWITCH ADDRESSES
        AX = 0306h
Return: CF clear
        BX:CX -> procedure to switch from real to protected mode
        SI:DI / SI:EDI -> procedure to switch from protected to real mode
Notes:  16-bit programs should jump to SI:DI, 32-bit programs should use SI:EDI
        the caller must save and restore the state of the task with AX=0305h
        not supported by MS Windows 3.0 in Standard mode

Values to JUMP at mode-switch procedures with:
        AX = new DS
        CX = new ES
        DX = new SS
        BX / EBX = new SP / ESP
        SI = new CS
        DI / EDI = new IP / EIP
Notes:  BP/EBP is preserved across the call, but AX/EAX, BX/EBX, CX/ECX,
          DX/EDX, SI/ESI, and DI/EDI will be undefined; FS and GS will be 0000h
        interrupts will stay disabled during the entire mode switch if they
          are disabled on entry to the mode-switch procedure