Path: utzoo!attcan!uunet!wuarchive!zaphod.mps.ohio-state.edu!ncar!noao!arizona!shack
From: shack@cs.arizona.edu (David Shackelford)
Newsgroups: comp.os.msdos.programmer
Subject: Re: Int 10H Function 13H - How Do I access BP from C ?
Message-ID: <488@caslon.cs.arizona.edu>
Date: 29 Oct 90 19:23:29 GMT
References: <1990Oct19.202013.28397@nada.kth.se> <1990Oct21.204236.22011@nada.kth.se> <685@digigw.digital.co.jp>
Organization: U of Arizona CS Dept, Tucson
Lines: 23

In article <685@digigw.digital.co.jp> gday@digigw.digital.co.jp (Gordon Day) writes:
>In article <1990Oct21.204236.22011@nada.kth.se>, d87-vik@dront.nada.kth.se (Ville K{rkk{inen) writes:
>> 
>> My problem is that Int10h-Func13h requires the offset of my data to be stored
>> in BP,that is, the BasePointer. Note this,BP is a pointer, not a register
>> defined in the REGS union. 
> [stuff on MSC & VAX deleted], but no compilers (to my knowledge) on the PC do,
>
>Gordon W. Day

TurboC has aliases to the actual registers defined, and you can directly write
to the hardware with a couple of restrictions.  You cannot change the segment
registers, SP, or BP.  Unfortunately, this means that the original poster
would not be able to use this anyway.

I don't understand why the int86?() functions don't work, as the regs structure
does contain a BP field, which is properly modified and sent to the BIOS func.
(At least it is in TURBOC, can't say for other compilers).  I use this all of
the time in my mouse handler functions.

Perhaps a code example from the non-working program might help to find a fix.

Dave    | shack@cs.arizona.edu