Fixed printer.c
Andy Tanenbaum
I would appreciate people trying it and reporting back on the results,
that is, which machine and printer it was tested on and what happened.
Andy Tanenbaum
------------------------------- cut here ---------------------------
/* This file contains the printer driver. It is a fairly simple driver,
* supporting only one printer. Characters that are written to the driver
* are written to the printer without any changes at all.
*
* The valid messages and their parameters are:
*
* TTY_O_DONE: output completed
* TTY_WRITE: a process wants to write on a terminal
* CANCEL: terminate a previous incomplete system call immediately
*
* m_type TTY_LINE PROC_NR COUNT ADDRESS
* -------------------------------------------------------
* | TTY_O_DONE |minor dev| | | |
* |-------------+---------+---------+---------+---------|
* | TTY_WRITE |minor dev| proc nr | count | buf ptr |
* |-------------+---------+---------+---------+---------|
* | CANCEL |minor dev| proc nr | | |
* -------------------------------------------------------
*
* Note: since only 1 printer is supported, minor dev is not used at present.
*/
#include "../h/const.h"
#include "../h/type.h"
#include "../h/callnr.h"
#include "../h/com.h"
#include "../h/error.h"
#include "const.h"
#include "type.h"
#include "glo.h"
#include "proc.h"
#define NORMAL_STATUS 0x90 /* printer gives this status when idle */
#define BUSY_STATUS 0x10 /* printer gives this status when busy */
#define ASSERT_STROBE 0x1D /* strobe a character to the interface */
#define NEGATE_STROBE 0x1C /* enable interrupt on interface */
#define SELECT 0x0C /* select printer bit */
#define INIT_PRINTER 0x08 /* init printer bits */
#define NO_PAPER 0x20 /* status bit saying that paper is up */
#define OFF_LINE 0x10 /* status bit saying that printer not online*/
#define PR_ERROR 0x08 /* something is wrong with the printer */
#define PR_COLOR_BASE 0x378 /* printer port when color display used */
#define PR_MONO_BASE 0x3BC /* printer port when mono display used */
#define LOW_FOUR 0xF /* mask for low-order 4 bits */
#define CANCELED -999 /* indicates that command has been killed */
#define DELAY_COUNT 100 /* regulates delay between characters */
#define DELAY_LOOP 1000 /* delay when printer is busy */
#define MAX_REP 1000 /* controls max delay when busy */
#define STATUS_MASK 0xB0 /* mask to filter out status bits */
PRIVATE int port_base; /* I/O port for printer: 0x 378 or 0x3BC */
PRIVATE int caller; /* process to tell when printing done (FS) */
PRIVATE int proc_nr; /* user requesting the printing */
PRIVATE int orig_count; /* original byte count */
PRIVATE int es; /* (es, offset) point to next character to */
PRIVATE int offset; /* print, i.e., in the user's buffer */
PUBLIC int pcount; /* number of bytes left to print */
PUBLIC int pr_busy; /* TRUE when printing, else FALSE */
PUBLIC int cum_count; /* cumulative # characters printed */
PUBLIC int prev_ct; /* value of cum_count 100 msec ago */
/*===========================================================================*
* printer_task *
*===========================================================================*/
PUBLIC printer_task()
{
/* Main routine of the printer task. */
message print_mess; /* buffer for all incoming messages */
print_init(); /* initialize */
while (TRUE) {
receive(ANY, &print_mess);
switch(print_mess.m_type) {
case TTY_WRITE: do_write(&print_mess); break;
case CANCEL : do_cancel(&print_mess); break;
case TTY_O_DONE: do_done(&print_mess); break;
default: break;
}
}
}
/*===========================================================================*
* do_write *
*===========================================================================*/
PRIVATE do_write(m_ptr)
message *m_ptr; /* pointer to the newly arrived message */
{
/* The printer is used by sending TTY_WRITE messages to it. Process one. */
int i, j, r, value;
struct proc *rp;
phys_bytes phys;
extern phys_bytes umap();
r = OK; /* so far, no errors */
/* Reject command if printer is busy or count is not positive. */
if (pr_busy) r = EAGAIN;
if (m_ptr->COUNT <= 0) r = EINVAL;
/* Compute the physical address of the data buffer within user space. */
rp = proc_addr(m_ptr->PROC_NR);
phys = umap(rp, D, (vir_bytes) m_ptr->ADDRESS, m_ptr->COUNT);
if (phys == 0) r = E_BAD_ADDR;
if (r == OK) {
/* Save information needed later. */
lock(); /* no interrupts now please */
caller = m_ptr->m_source;
proc_nr = m_ptr->PROC_NR;
pcount = m_ptr->COUNT;
orig_count = m_ptr->COUNT;
es = (int) (phys >> CLICK_SHIFT);
offset = (int) (phys & LOW_FOUR);
/* Start the printer. */
for (i = 0; i < MAX_REP; i++) {
port_in(port_base + 1, &value);
if (value&STATUS_MASK == NORMAL_STATUS) {
pr_busy = TRUE;
pr_char(); /* print first character */
r = SUSPEND; /* tell FS to suspend user until done */
break;
} else {
if (value&STATUS_MASK == BUSY_STATUS) {
for (j = 0; j <DELAY_LOOP; j++) /* delay */ ;
continue;
}
pr_error(value);
r = EIO;
break;
}
}
}
/* Reply to FS, no matter what happened. */
if (value&STATUS_MASK == BUSY_STATUS) r = EAGAIN;
reply(TASK_REPLY, m_ptr->m_source, m_ptr->PROC_NR, r);
}
/*===========================================================================*
* do_done *
*===========================================================================*/
PRIVATE do_done(m_ptr)
message *m_ptr; /* pointer to the newly arrived message */
{
/* Printing is finished. Reply to caller (FS). */
int status;
status = (m_ptr->REP_STATUS == OK ? orig_count : EIO);
if (proc_nr != CANCELED) {
reply(REVIVE, caller, proc_nr, status);
if (status == EIO) pr_error(m_ptr->REP_STATUS);
}
pr_busy = FALSE;
}
/*===========================================================================*
* do_cancel *
*===========================================================================*/
PRIVATE do_cancel(m_ptr)
message *m_ptr; /* pointer to the newly arrived message */
{
/* Cancel a print request that has already started. Usually this means that
* the process doing the printing has been killed by a signal.
*/
if (pr_busy == FALSE) return; /* this statement avoids race conditions */
pr_busy = FALSE; /* mark printer as idle */
pcount = 0; /* causes printing to stop at next interrupt*/
proc_nr = CANCELED; /* marks process as canceled */
reply(TASK_REPLY, m_ptr->m_source, m_ptr->PROC_NR, EINTR);
}
/*===========================================================================*
* reply *
*===========================================================================*/
PRIVATE reply(code, replyee, process, status)
int code; /* TASK_REPLY or REVIVE */
int replyee; /* destination for message (normally FS) */
int process; /* which user requested the printing */
int status; /* number of chars printed or error code */
{
/* Send a reply telling FS that printing has started or stopped. */
message pr_mess;
pr_mess.m_type = code; /* TASK_REPLY or REVIVE */
pr_mess.REP_STATUS = status; /* count or EIO */
pr_mess.REP_PROC_NR = process; /* which user does this pertain to */
send(replyee, &pr_mess); /* send the message */
}
/*===========================================================================*
* pr_error *
*===========================================================================*/
PRIVATE pr_error(status)
int status; /* printer status byte */
{
/* The printer is not ready. Display a message on the console telling why. */
if (status & NO_PAPER) printf("Printer is out of paper\n");
if ((status & OFF_LINE) == 0) printf("Printer is not on line\n");
if ((status & PR_ERROR) == 0) printf("Printer error\n");
}
/*===========================================================================*
* print_init *
*===========================================================================*/
PRIVATE print_init()
{
/* Color display uses 0x378 for printer; mono display uses 0x3BC. */
int i;
extern int color;
port_base = (color ? PR_COLOR_BASE : PR_MONO_BASE);
pr_busy = FALSE;
port_out(port_base + 2, INIT_PRINTER);
for (i = 0; i < DELAY_COUNT; i++) ; /* delay loop */
port_out(port_base + 2, SELECT);
}
/*===========================================================================*
* pr_char *
*===========================================================================*/
PUBLIC pr_char()
{
/* This is the interrupt handler. When a character has been printed, an
* interrupt occurs, and the assembly code routine trapped to calls pr_char().
* One annoying problem is that the 8259A controller sometimes generates
* spurious interrupts to vector 15, which is the printer vector. Ignore them.
*/
int value, ch, i;
char c;
extern char get_byte();
if (pcount != orig_count) port_out(INT_CTL, ENABLE);
if (pr_busy == FALSE) return; /* spurious 8259A interrupt */
while (pcount > 0) {
port_in(port_base + 1, &value); /* get printer status */
if (value&STATUS_MASK == NORMAL_STATUS) {
/* Everything is all right. Output another character. */
c = get_byte(es, offset); /* fetch char from user buf */
ch = c & BYTE;
port_out(port_base, ch); /* output character */
port_out(port_base + 2, ASSERT_STROBE);
port_out(port_base + 2, NEGATE_STROBE);
offset++;
pcount--;
cum_count++; /* count characters output */
for (i = 0; i < DELAY_COUNT; i++) ; /* delay loop */
} else if (value&STATUS_MASK == BUSY_STATUS) {
return; /* printer is busy; wait for interrupt*/
} else {
break; /* err: send message to printer task */
}
}
/* Count is 0 or an error occurred; send message to printer task. */
int_mess.m_type = TTY_O_DONE;
int_mess.REP_STATUS = (pcount == 0 ? OK : value);
interrupt(PRINTER, &int_mess);
}
Smagt v der PPP
This is the new "official" printer driver. It has several bugs fixed.
I would appreciate people trying it and reporting back on the results,
that is, which machine and printer it was tested on and what happened.
Andy Tanenbaum
I removed the bugs concerning parentheses.
Patrick van der Smagt
print_init(); /* initialize */
if ((value&STATUS_MASK) == NORMAL_STATUS) {
pr_busy = TRUE;
pr_char(); /* print first character */
r = SUSPEND; /* tell FS to suspend user until done */
break;
} else {
if ((value&STATUS_MASK) == BUSY_STATUS) {
for (j = 0; j <DELAY_LOOP; j++) /* delay */ ;
continue;
}
pr_error(value);
r = EIO;
break;
}
}
}
/* Reply to FS, no matter what happened. */
if ((value&STATUS_MASK) == BUSY_STATUS) r = EAGAIN;
int status;
message pr_mess;
if ((value&STATUS_MASK) == NORMAL_STATUS) {
/* Everything is all right. Output another character. */
c = get_byte(es, offset); /* fetch char from user buf */
ch = c & BYTE;
port_out(port_base, ch); /* output character */
port_out(port_base + 2, ASSERT_STROBE);
port_out(port_base + 2, NEGATE_STROBE);
offset++;
pcount--;
cum_count++; /* count characters output */
for (i = 0; i < DELAY_COUNT; i++) ; /* delay loop */
} else if ((value&STATUS_MASK) == BUSY_STATUS) {