Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!att!ucbvax!ASYLUM.SF.CA.US!romkey
From: romkey@ASYLUM.SF.CA.US (John Romkey)
Newsgroups: comp.protocols.tcp-ip.ibmpc
Subject: Turbo C and Packet Drivers
Message-ID: <9104111202.AA08768@asylum.sf.ca.us>
Date: 11 Apr 91 19:02:38 GMT
References: <9104111614.AA09977@ftp.com>
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: romkey@asylum.sf.ca.us
Organization: The Internet
Lines: 21


   Date: Thu, 11 Apr 91 12:14:35 -0400
   From: "James B. Van Bokkelen" <jbvb@ftp.com>
   Reply-To: jbvb@ftp.com

   Our protocol stacks use a small ASM routine to save the registers and
   switch to a stack of their own, and then call C to do the bulk of the
   work.  You can probably use a compiler's "interrupt" function mechanism
   to make it work, but you'll be relying on the driver leaving you enough
   stack.  I don't have experience with Turbo's "interrupt" functions, and
   while I know MSC can do them, I've never found the place in the manual
   where they're explained.

Declaring a function as 'interrupt' probably won't work properly.
'interrupt' functions do indeed save and restore all the registers,
but they also expect the stack frame to be the same format as an
interrupt stack frame, which means the flags register is pushed on the
stack and popped off it on return. The packet drivers won't have left
the flags register on the stack, so the stack will get screwed up.
		- john romkey			Epilogue Technology
USENET/UUCP/Internet:  romkey@asylum.sf.ca.us	voice/fax: 415 594-1141