Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!ptsfa!lll-tis!lll-lcc!rutgers!cmcl2!brl-adm!umd5!purdue!i.cc.purdue.edu!j.cc.purdue.edu!pur-ee!ea.ecn.purdue.edu!housel
From: housel@ea.ecn.purdue.edu (Peter S. Housel)
Newsgroups: comp.os.minix
Subject: Re: Problems with Jim Paradis' tty driver
Message-ID: <1509@ea.ecn.purdue.edu>
Date: 17 Jan 88 03:05:46 GMT
References: <1828@botter.cs.vu.nl>
Reply-To: housel@ea.ecn.purdue.edu.UUCP (Peter S. Housel)
Organization: Purdue University Engineering Computer Network
Lines: 57


	Here's a patch for Jim Paradis' new tty driver to allow it to work
on HGC cards (mine anyway). Apply this diff to console.c:
-----------------------------cut----------------------------------------
530,531c530,531
< 		oque[oque_last].address = cur_start +
< 				( ((crow * NCOLS) + ccol) << 1);
---
> 		oque[oque_last].address = (cur_start +
> 				( ((crow * NCOLS) + ccol) << 1)) & SEG_MASK;
542,545c542,545
< 		    (int)(cur_start + (((crow * NCOLS) + ccol) << 1)),
< 		    (int)ch);
< 		put_byte(VIDEO_SEG,
< 		    (int)(cur_start + (((crow * NCOLS) + ccol) << 1)) + 1,
---
> 		    (int)(cur_start + (((crow * NCOLS) + ccol) << 1)) & SEG_MASK,
> 		    (int)ch);
> 		put_byte(VIDEO_SEG,
> 		    (int)((cur_start + (((crow * NCOLS) + ccol) << 1)) + 1) & SEG_MASK,
-----------------------------cut----------------------------------------
	Also, if you're going to run without CHEAP_CGA defined, you
need to add the following (fairly obvious) routine to klib88.s:

-----------------------------cut----------------------------------------
.globl _put_byte
|*===========================================================================*
|*				put_byte				     *
|*===========================================================================*
| This routine is used to stuff a byte anywhere in memory.
| The call is:
|     c = put_byte(seg, off, byte)
| where
|     'seg' is the value to put in es
|     'off' is the offset from the es value
|     'byte' is the byte to be placed
_put_byte:
	push bp			| save bp
	mov bp,sp		| we need to access parameters
	push es			| save es
	mov es,4(bp)		| load es with segment value
	mov bx,6(bp)		| load bx with offset from segment
	mov ax,8(bp)
	seg es			| go get the byte
	movb (bx),al		| al = byte
	pop es			| restore es
	pop bp			| restore bp
	ret			| return to caller
-----------------------------cut----------------------------------------

	I haven't had such good luck with the driver itself. Running
the "t.c" program, and configuring rs232.c to work at 1200 baud, it misses
about three of every five characters.

	-Peter S. Housel-
	housel@ei.ecn.purdue.edu
	...!pur-ee!housel