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Path: utzoo!mnetor!seismo!mcvax!botter!ark!smagt
From: smagt@ark.cs.vu.nl (Smagt v der PPP)
Newsgroups: comp.os.minix
Subject: minix printer driver
Message-ID: <922@ark.cs.vu.nl>
Date: Fri, 6-Mar-87 07:23:48 EST
Article-I.D.: ark.922
Posted: Fri Mar  6 07:23:48 1987
Date-Received: Sun, 8-Mar-87 06:52:26 EST
Organization: V.U. Informatica, Amsterdam, the Netherlands
Lines: 36
Keywords: bugs (?) in printer.c

The MINIX printer driver may not work for all printers. The trouble
is this. Printer.c expects a printer status of 0xDF when the printer
is ready, or 0x5F when the printer is busy. I discovered, however,
that some printers (e.g. mine) return some other values as well:
0xDC and 0xD8 when ready, or 0x58 or 0x5C when busy. So I adapted
printer.c to be less choosy, i.e. to accept all 0xD? as "ready"
and 0x5? as "busy" status.
The patches are these:

on line 121, change
	  	if (value == NORMAL_STATUS) {
to
		if ((value | LOW_FOUR) == NORMAL_STATUS) {
on line 127, change
			if (value == BUSY_STATUS) {
to
			if ((value | LOW_FOUR) == BUSY_STATUS) {
on line 139, change
  if (value == BUSY_STATUS) r = EAGAIN;
to
  if ((value | LOW_FOUR) == BUSY_STATUS) r = EAGAIN;
on line 253, change
  	if (value == NORMAL_STATUS) {
to
	if ((value | LOW_FOUR) == NORMAL_STATUS) {
and on line 264, change
	} else if (value == BUSY_STATUS) {
to
	} else if ((value | LOW_FOUR) == BUSY_STATUS) {

I deliberately didn't change the 'value' itself, because other
programs (e.g. lpr) use its value to print an error message (if
anything is wrong).
Prof. Tanenbaum accepted my patched readily.

				P.P.Patrick van der Smagt.