'Getting MS-DOS SMARTDrive version from interrupt call 2F/AX=4A10h/BX=0000h

I'm trying to write an assembly procedure to get the SMARTDrive version on a given system. The code to detect if SMARTDrive is loaded works correctly, but I can't seem to get the version from the Base Pointer (BP) register. My compiler, Digital Mars, doesn't seem to support the BP register in the REGS structure of DOS.H, so I can't use regs.x.bp.

I'm using Ralph Brown's Interrupt List as a guide, located here: http://www.ctyme.com/intr/rb-4822.htm

Here's the code I'm working with:

.MODEL Large, C
PUBLIC _get_smartdrive_version

_get_smartdrive_version proc
    cli
    mov ax, 4A10h
    mov bx, 0000h
    mov cx, 0EBABh
    int 2Fh
    cmp ax, 0BABEh          ; verify SMARTDrive signature
    jne no_smartdrv
    xor ax, ax              ; probably not needed
    mov ax, dword ptr [bp]  ; (note also tried without dword ptr, and with es:[bp])
    jmp done
no_smartdrv:
    mov ax, 0
done:
    sti
    ret
_get_smartdrive_version endp

end

This should return the version in the AX register, but when I run this code it hangs my system. I'm not really sure how to access the data in the BP register without locking up the system. Does anyone else have experience on how to do this correctly? Is there a better way to accomplish this? Any help is greatly appreciated!

assemblydosx86-16


Solution 1:[1]

switching the line mov ax, dword ptr [bp] to mov ax, bp worked. Thanks to @ecm for the assistance!

Sources

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Source: Stack Overflow

Solution Source
Solution 1 Charlie Dobson

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