lp.c

UNIX v6源代码 这几乎是最经典的unix版本 unix操作系统设计和莱昂氏unix源代码分析都是用的该版

#
/*
 */

/*
 * LP-11 Line printer driver
 */

#include "../param.h"
#include "../conf.h"
#include "../user.h"

#define	LPADDR	0177514

#define	IENABLE	0100
#define	DONE	0200

#define	LPPRI	10
#define	LPLWAT	50
#define	LPHWAT	100
#define	EJLINE	60
#define	MAXCOL	80

struct {
	int lpsr;
	int lpbuf;
};

struct  {
	int	cc;
	int	cf;
	int	cl;
	int	flag;
	int	mcc;
	int	ccc;
	int	mlc;
} lp11;

#define	CAP	01		/* Set to 0 for 96-char printer, else to 01 */
#define	EJECT	02
#define	OPEN	04
#define IND	010		/* Set to 0 for no indent, else to 010 */

#define	FORM	014

lpopen(dev, flag)
{

	if(lp11.flag & OPEN || LPADDR->lpsr < 0) {
		u.u_error = EIO;
		return;
	}
	lp11.flag =| (IND|EJECT|OPEN);
	LPADDR->lpsr =| IENABLE;
	lpcanon(FORM);
}

lpclose(dev, flag)
{
	lpcanon(FORM);
	lp11.flag = 0;
}

lpwrite()
{
	register int c;

	while ((c=cpass())>=0)
		lpcanon(c);
}

lpcanon(c)
{
	register c1, c2;

	c1 = c;
	if(lp11.flag&CAP) {
		if(c1>='a' && c1<='z')
			c1 =+ 'A'-'a'; else
		switch(c1) {

		case '{':
			c2 = '(';
			goto esc;

		case '}':
			c2 = ')';
			goto esc;

		case '`':
			c2 = '\'';
			goto esc;

		case '|':
			c2 = '!';
			goto esc;

		case '~':
			c2 = '^';

		esc:
			lpcanon(c2);
			lp11.ccc--;
			c1 = '-';
		}
	}

	switch(c1) {

	case '\t':
		lp11.ccc = (lp11.ccc+8) & ~7;
		return;

	case FORM:
	case '\n':
		if((lp11.flag&EJECT) == 0 ||
		   lp11.mcc!=0 || lp11.mlc!=0) {
			lp11.mcc = 0;
			lp11.mlc++;
			if(lp11.mlc >= EJLINE && lp11.flag&EJECT)
				c1 = FORM;
			lpoutput(c1);
			if(c1 == FORM)
				lp11.mlc = 0;
		}

	case '\r':
		lp11.ccc = 0;
		if(lp11.flag&IND)
			lp11.ccc = 8;
		return;

	case 010:
		if(lp11.ccc > 0)
			lp11.ccc--;
		return;

	case ' ':
		lp11.ccc++;
		return;

	default:
		if(lp11.ccc < lp11.mcc) {
			lpoutput('\r');
			lp11.mcc = 0;
		}
		if(lp11.ccc < MAXCOL) {
			while(lp11.ccc > lp11.mcc) {
				lpoutput(' ');
				lp11.mcc++;
			}
			lpoutput(c1);
			lp11.mcc++;
		}
		lp11.ccc++;
	}
}

lpstart()
{
	register int c;

	while (LPADDR->lpsr&DONE && (c = getc(&lp11)) >= 0)
		LPADDR->lpbuf = c;
}

lpint()
{
	register int c;

	lpstart();
	if (lp11.cc == LPLWAT || lp11.cc == 0)
		wakeup(&lp11);
}

lpoutput(c)
{
	if (lp11.cc >= LPHWAT)
		sleep(&lp11, LPPRI);
	putc(c, &lp11);
	spl4();
	lpstart();
	spl0();
}