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From: erick@DEVELOPMENT.WATSTAR.UWATERLOO.CA
Newsgroups: comp.protocols.tcp-ip.ibmpc
Subject: (none)
Message-ID: <9104112354.AA26361@watserv1.uwaterloo.ca>
Date: 12 Apr 91 00:50:48 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 43


John Haskey wrote:
>Does anyone out there have some example code that shows how to talk to a
>packet driver from Turbo C?  I can get everything going except for the
>most important:  The receiver routine specified in the call to access_type().

The following is Turbo C code which seems to work with every packet
driver I've tried.  Remember, you could be running with VERY LITTLE stack
space, so don't use very few local variables, avoid function calls and avoid
DOS and the BIOS.  This version saves all the registers on the stack as
integers.

I have only tested this in small model, and notice how Turbo C correctly
converts the pointer to 32 bits.

typedef struct farcallstr{
    UCHAR       pushf;
    UCHAR       callfar;
    void interrupt (*introutine)();
    UCHAR       retf;
};

void interrupt ourint(bp,di,si,ds,es,dx,cx,bx,ax,ip,cs,flgs)
{
    switch ( ax ) {
       case  0 : /* initial call - allocate a buffer */
                 break;
       case  1 : /* indicates packet is ready */
                 break;
       }
}

struct farcallstr farcall = { 0x9c, 0x9a, ourint, 0xcb};

When you do the packet driver installation, remember to set es to 
FP_SEG( &farcall).  Turbo C will return the correct segment.  To transfer
the parameters, you should probably use intr() rather than _ES, _DS
and the inline geninterrupt() which may fail when some drivers do not
restore the segment registers.

Good luck.

Erick