哈工大操作系统实验 6 字符显示的控制

这次试验相当简单，没啥好说的

//=====================================================================

1.按下F12后，调用了keyboard.c中call show_stat，show_stat在sched.c中它又调用了show_task()函数，打印了当前进程的一些信息。
2.不影响到文件的输出，console.c中con_write函数实现的，这个文件是实现控制台输入输出模块的，所以不会影响对于文件的读写。想要影响到文件需要修改file_write函数。

//=====================================================================

linux-0.11/kernel/chr_drv/keyboard.S

注释掉214行的

call show_stat

linux-0.11/kernel/chr_drv/tty_io.c

修改了copy_to_cooked函数

/*
 *  linux/kernel/tty_io.c
 *
 *  (C) 1991  Linus Torvalds
 */

/*
 * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
 * or rs-channels. It also implements echoing, cooked mode etc.
 *
 * Kill-line thanks to John T Kohl.
 */
#include <ctype.h>
#include <errno.h>
#include <signal.h>

#define ALRMMASK (1<<(SIGALRM-1))
#define KILLMASK (1<<(SIGKILL-1))
#define INTMASK (1<<(SIGINT-1))
#define QUITMASK (1<<(SIGQUIT-1))
#define TSTPMASK (1<<(SIGTSTP-1))

#include <linux/sched.h>
#include <linux/tty.h>
#include <asm/segment.h>
#include <asm/system.h>

#define _L_FLAG(tty,f)	((tty)->termios.c_lflag & f)
#define _I_FLAG(tty,f)	((tty)->termios.c_iflag & f)
#define _O_FLAG(tty,f)	((tty)->termios.c_oflag & f)

#define L_CANON(tty)	_L_FLAG((tty),ICANON)
#define L_ISIG(tty)	_L_FLAG((tty),ISIG)
#define L_ECHO(tty)	_L_FLAG((tty),ECHO)
#define L_ECHOE(tty)	_L_FLAG((tty),ECHOE)
#define L_ECHOK(tty)	_L_FLAG((tty),ECHOK)
#define L_ECHOCTL(tty)	_L_FLAG((tty),ECHOCTL)
#define L_ECHOKE(tty)	_L_FLAG((tty),ECHOKE)

#define I_UCLC(tty)	_I_FLAG((tty),IUCLC)
#define I_NLCR(tty)	_I_FLAG((tty),INLCR)
#define I_CRNL(tty)	_I_FLAG((tty),ICRNL)
#define I_NOCR(tty)	_I_FLAG((tty),IGNCR)

#define O_POST(tty)	_O_FLAG((tty),OPOST)
#define O_NLCR(tty)	_O_FLAG((tty),ONLCR)
#define O_CRNL(tty)	_O_FLAG((tty),OCRNL)
#define O_NLRET(tty)	_O_FLAG((tty),ONLRET)
#define O_LCUC(tty)	_O_FLAG((tty),OLCUC)

struct tty_struct tty_table[] = {
	{
		{ICRNL,		/* change incoming CR to NL */
		OPOST|ONLCR,	/* change outgoing NL to CRNL */
		0,
		ISIG | ICANON | ECHO | ECHOCTL | ECHOKE,
		0,		/* console termio */
		INIT_C_CC},
		0,			/* initial pgrp */
		0,			/* initial stopped */
		con_write,
		{0,0,0,0,""},		/* console read-queue */
		{0,0,0,0,""},		/* console write-queue */
		{0,0,0,0,""}		/* console secondary queue */
	},{
		{0, /* no translation */
		0,  /* no translation */
		B2400 | CS8,
		0,
		0,
		INIT_C_CC},
		0,
		0,
		rs_write,
		{0x3f8,0,0,0,""},		/* rs 1 */
		{0x3f8,0,0,0,""},
		{0,0,0,0,""}
	},{
		{0, /* no translation */
		0,  /* no translation */
		B2400 | CS8,
		0,
		0,
		INIT_C_CC},
		0,
		0,
		rs_write,
		{0x2f8,0,0,0,""},		/* rs 2 */
		{0x2f8,0,0,0,""},
		{0,0,0,0,""}
	}
};

/*
 * these are the tables used by the machine code handlers.
 * you can implement pseudo-tty's or something by changing
 * them. Currently not done.
 */
struct tty_queue * table_list[]={
	&tty_table[0].read_q, &tty_table[0].write_q,
	&tty_table[1].read_q, &tty_table[1].write_q,
	&tty_table[2].read_q, &tty_table[2].write_q
	};

void tty_init(void)
{
	rs_init();
	con_init();
}

void tty_intr(struct tty_struct * tty, int mask)
{
	int i;

	if (tty->pgrp <= 0)
		return;
	for (i=0;i<NR_TASKS;i++)
		if (task[i] && task[i]->pgrp==tty->pgrp)
			task[i]->signal |= mask;
}

static void sleep_if_empty(struct tty_queue * queue)
{
	cli();
	while (!current->signal && EMPTY(*queue))
		interruptible_sleep_on(&queue->proc_list);
	sti();
}

static void sleep_if_full(struct tty_queue * queue)
{
	if (!FULL(*queue))
		return;
	cli();
	while (!current->signal && LEFT(*queue)<128)
		interruptible_sleep_on(&queue->proc_list);
	sti();
}

void wait_for_keypress(void)
{
	sleep_if_empty(&tty_table[0].secondary);
}

void copy_to_cooked(struct tty_struct * tty)
{
        signed char c;

        while (!EMPTY(tty->read_q) && !FULL(tty->secondary)) {
                GETCH(tty->read_q,c);
                if (c=='L'){
                        if (judge) judge=0;
                        else judge=1;
                        break;
                }
		if (c==13)
			if (I_CRNL(tty))
				c=10;
			else if (I_NOCR(tty))
				continue;
			else ;
		else if (c==10 && I_NLCR(tty))
			c=13;
		if (I_UCLC(tty))
			c=tolower(c);
		if (L_CANON(tty)) {
			if (c==KILL_CHAR(tty)) {
				/* deal with killing the input line */
				while(!(EMPTY(tty->secondary) ||
				        (c=LAST(tty->secondary))==10 ||
				        c==EOF_CHAR(tty))) {
					if (L_ECHO(tty)) {
						if (c<32)
							PUTCH(127,tty->write_q);
						PUTCH(127,tty->write_q);
						tty->write(tty);
					}
					DEC(tty->secondary.head);
				}
				continue;
			}
			if (c==ERASE_CHAR(tty)) {
				if (EMPTY(tty->secondary) ||
				   (c=LAST(tty->secondary))==10 ||
				   c==EOF_CHAR(tty))
					continue;
				if (L_ECHO(tty)) {
					if (c<32)
						PUTCH(127,tty->write_q);
					PUTCH(127,tty->write_q);
					tty->write(tty);
				}
				DEC(tty->secondary.head);
				continue;
			}
			if (c==STOP_CHAR(tty)) {
				tty->stopped=1;
				continue;
			}
			if (c==START_CHAR(tty)) {
				tty->stopped=0;
				continue;
			}
		}
		if (L_ISIG(tty)) {
			if (c==INTR_CHAR(tty)) {
				tty_intr(tty,INTMASK);
				continue;
			}
			if (c==QUIT_CHAR(tty)) {
				tty_intr(tty,QUITMASK);
				continue;
			}
		}
		if (c==10 || c==EOF_CHAR(tty))
			tty->secondary.data++;
		if (L_ECHO(tty)) {
			if (c==10) {
				PUTCH(10,tty->write_q);
				PUTCH(13,tty->write_q);
			} else if (c<32) {
				if (L_ECHOCTL(tty)) {
					PUTCH('^',tty->write_q);
					PUTCH(c+64,tty->write_q);
				}
			} else
				PUTCH(c,tty->write_q);
			tty->write(tty);
		}
		PUTCH(c,tty->secondary);
	}
	wake_up(&tty->secondary.proc_list);
}

int tty_read(unsigned channel, char * buf, int nr)
{
	struct tty_struct * tty;
	char c, * b=buf;
	int minimum,time,flag=0;
	long oldalarm;

	if (channel>2 || nr<0) return -1;
	tty = &tty_table[channel];
	oldalarm = current->alarm;
	time = 10L*tty->termios.c_cc[VTIME];
	minimum = tty->termios.c_cc[VMIN];
	if (time && !minimum) {
		minimum=1;
		if ((flag=(!oldalarm || time+jiffies<oldalarm)))
			current->alarm = time+jiffies;
	}
	if (minimum>nr)
		minimum=nr;
	while (nr>0) {
		if (flag && (current->signal & ALRMMASK)) {
			current->signal &= ~ALRMMASK;
			break;
		}
		if (current->signal)
			break;
		if (EMPTY(tty->secondary) || (L_CANON(tty) &&
		!tty->secondary.data && LEFT(tty->secondary)>20)) {
			sleep_if_empty(&tty->secondary);
			continue;
		}
		do {
			GETCH(tty->secondary,c);
			if (c==EOF_CHAR(tty) || c==10)
				tty->secondary.data--;
			if (c==EOF_CHAR(tty) && L_CANON(tty))
				return (b-buf);
			else {
				put_fs_byte(c,b++);
				if (!--nr)
					break;
			}
		} while (nr>0 && !EMPTY(tty->secondary));
		if (time && !L_CANON(tty)) {
			if ((flag=(!oldalarm || time+jiffies<oldalarm)))
				current->alarm = time+jiffies;
			else
				current->alarm = oldalarm;
		}
		if (L_CANON(tty)) {
			if (b-buf)
				break;
		} else if (b-buf >= minimum)
			break;
	}
	current->alarm = oldalarm;
	if (current->signal && !(b-buf))
		return -EINTR;
	return (b-buf);
}

int tty_write(unsigned channel, char * buf, int nr)
{
	static int cr_flag=0;
	struct tty_struct * tty;
	char c, *b=buf;

	if (channel>2 || nr<0) return -1;
	tty = channel + tty_table;
	while (nr>0) {
		sleep_if_full(&tty->write_q);
		if (current->signal)
			break;
		while (nr>0 && !FULL(tty->write_q)) {
			c=get_fs_byte(b);
			if (O_POST(tty)) {
				if (c=='\r' && O_CRNL(tty))
					c='\n';
				else if (c=='\n' && O_NLRET(tty))
					c='\r';
				if (c=='\n' && !cr_flag && O_NLCR(tty)) {
					cr_flag = 1;
					PUTCH(13,tty->write_q);
					continue;
				}
				if (O_LCUC(tty))
					c=toupper(c);
			}
			b++; nr--;
			cr_flag = 0;
			PUTCH(c,tty->write_q);
		}
		tty->write(tty);
		if (nr>0)
			schedule();
	}
	return (b-buf);
}

/*
 * Jeh, sometimes I really like the 386.
 * This routine is called from an interrupt,
 * and there should be absolutely no problem
 * with sleeping even in an interrupt (I hope).
 * Of course, if somebody proves me wrong, I'll
 * hate intel for all time :-). We'll have to
 * be careful and see to reinstating the interrupt
 * chips before calling this, though.
 *
 * I don't think we sleep here under normal circumstances
 * anyway, which is good, as the task sleeping might be
 * totally innocent.
 */
void do_tty_interrupt(int tty)
{
	copy_to_cooked(tty_table+tty);
}

void chr_dev_init(void)
{
}

linux-0.11/kernel/chr_drv/tty_io.c

修改了con_write函数

/*
 *  linux/kernel/console.c
 *
 *  (C) 1991  Linus Torvalds
 */

/*
 *	console.c
 *
 * This module implements the console io functions
 *	'void con_init(void)'
 *	'void con_write(struct tty_queue * queue)'
 * Hopefully this will be a rather complete VT102 implementation.
 *
 * Beeping thanks to John T Kohl.
 */

/*
 *  NOTE!!! We sometimes disable and enable interrupts for a short while
 * (to put a word in video IO), but this will work even for keyboard
 * interrupts. We know interrupts aren't enabled when getting a keyboard
 * interrupt, as we use trap-gates. Hopefully all is well.
 */

/*
 * Code to check for different video-cards mostly by Galen Hunt,
 * <[email protected]>
 */

#include <linux/sched.h>
#include <linux/tty.h>
#include <asm/io.h>
#include <asm/system.h>

/*
 * These are set up by the setup-routine at boot-time:
 */

#define ORIG_X			(*(unsigned char *)0x90000)
#define ORIG_Y			(*(unsigned char *)0x90001)
#define ORIG_VIDEO_PAGE		(*(unsigned short *)0x90004)
#define ORIG_VIDEO_MODE		((*(unsigned short *)0x90006) & 0xff)
#define ORIG_VIDEO_COLS 	(((*(unsigned short *)0x90006) & 0xff00) >> 8)
#define ORIG_VIDEO_LINES	(25)
#define ORIG_VIDEO_EGA_AX	(*(unsigned short *)0x90008)
#define ORIG_VIDEO_EGA_BX	(*(unsigned short *)0x9000a)
#define ORIG_VIDEO_EGA_CX	(*(unsigned short *)0x9000c)

#define VIDEO_TYPE_MDA		0x10	/* Monochrome Text Display	*/
#define VIDEO_TYPE_CGA		0x11	/* CGA Display 			*/
#define VIDEO_TYPE_EGAM		0x20	/* EGA/VGA in Monochrome Mode	*/
#define VIDEO_TYPE_EGAC		0x21	/* EGA/VGA in Color Mode	*/

#define NPAR 16

extern void keyboard_interrupt(void);

static unsigned char	video_type;		/* Type of display being used	*/
static unsigned long	video_num_columns;	/* Number of text columns	*/
static unsigned long	video_size_row;		/* Bytes per row		*/
static unsigned long	video_num_lines;	/* Number of test lines		*/
static unsigned char	video_page;		/* Initial video page		*/
static unsigned long	video_mem_start;	/* Start of video RAM		*/
static unsigned long	video_mem_end;		/* End of video RAM (sort of)	*/
static unsigned short	video_port_reg;		/* Video register select port	*/
static unsigned short	video_port_val;		/* Video register value port	*/
static unsigned short	video_erase_char;	/* Char+Attrib to erase with	*/

static unsigned long	origin;		/* Used for EGA/VGA fast scroll	*/
static unsigned long	scr_end;	/* Used for EGA/VGA fast scroll	*/
static unsigned long	pos;
static unsigned long	x,y;
static unsigned long	top,bottom;
static unsigned long	state=0;
static unsigned long	npar,par[NPAR];
static unsigned long	ques=0;
static unsigned char	attr=0x07;

static void sysbeep(void);

/*
 * this is what the terminal answers to a ESC-Z or csi0c
 * query (= vt100 response).
 */
#define RESPONSE "\033[?1;2c"

/* NOTE! gotoxy thinks x==video_num_columns is ok */
static inline void gotoxy(unsigned int new_x,unsigned int new_y)
{
	if (new_x > video_num_columns || new_y >= video_num_lines)
		return;
	x=new_x;
	y=new_y;
	pos=origin + y*video_size_row + (x<<1);
}

static inline void set_origin(void)
{
	cli();
	outb_p(12, video_port_reg);
	outb_p(0xff&((origin-video_mem_start)>>9), video_port_val);
	outb_p(13, video_port_reg);
	outb_p(0xff&((origin-video_mem_start)>>1), video_port_val);
	sti();
}

static void scrup(void)
{
	if (video_type == VIDEO_TYPE_EGAC || video_type == VIDEO_TYPE_EGAM)
	{
		if (!top && bottom == video_num_lines) {
			origin += video_size_row;
			pos += video_size_row;
			scr_end += video_size_row;
			if (scr_end > video_mem_end) {
				__asm__("cld\n\t"
					"rep\n\t"
					"movsl\n\t"
					"movl video_num_columns,%1\n\t"
					"rep\n\t"
					"stosw"
					::"a" (video_erase_char),
					"c" ((video_num_lines-1)*video_num_columns>>1),
					"D" (video_mem_start),
					"S" (origin)
					);
				scr_end -= origin-video_mem_start;
				pos -= origin-video_mem_start;
				origin = video_mem_start;
			} else {
				__asm__("cld\n\t"
					"rep\n\t"
					"stosw"
					::"a" (video_erase_char),
					"c" (video_num_columns),
					"D" (scr_end-video_size_row)
					);
			}
			set_origin();
		} else {
			__asm__("cld\n\t"
				"rep\n\t"
				"movsl\n\t"
				"movl video_num_columns,%%ecx\n\t"
				"rep\n\t"
				"stosw"
				::"a" (video_erase_char),
				"c" ((bottom-top-1)*video_num_columns>>1),
				"D" (origin+video_size_row*top),
				"S" (origin+video_size_row*(top+1))
				);
		}
	}
	else		/* Not EGA/VGA */
	{
		__asm__("cld\n\t"
			"rep\n\t"
			"movsl\n\t"
			"movl video_num_columns,%%ecx\n\t"
			"rep\n\t"
			"stosw"
			::"a" (video_erase_char),
			"c" ((bottom-top-1)*video_num_columns>>1),
			"D" (origin+video_size_row*top),
			"S" (origin+video_size_row*(top+1))
			);
	}
}

static void scrdown(void)
{
	if (video_type == VIDEO_TYPE_EGAC || video_type == VIDEO_TYPE_EGAM)
	{
		__asm__("std\n\t"
			"rep\n\t"
			"movsl\n\t"
			"addl $2,%%edi\n\t"	/* %edi has been decremented by 4 */
			"movl video_num_columns,%%ecx\n\t"
			"rep\n\t"
			"stosw"
			::"a" (video_erase_char),
			"c" ((bottom-top-1)*video_num_columns>>1),
			"D" (origin+video_size_row*bottom-4),
			"S" (origin+video_size_row*(bottom-1)-4)
			);
	}
	else		/* Not EGA/VGA */
	{
		__asm__("std\n\t"
			"rep\n\t"
			"movsl\n\t"
			"addl $2,%%edi\n\t"	/* %edi has been decremented by 4 */
			"movl video_num_columns,%%ecx\n\t"
			"rep\n\t"
			"stosw"
			::"a" (video_erase_char),
			"c" ((bottom-top-1)*video_num_columns>>1),
			"D" (origin+video_size_row*bottom-4),
			"S" (origin+video_size_row*(bottom-1)-4)
			);
	}
}

static void lf(void)
{
	if (y+1<bottom) {
		y++;
		pos += video_size_row;
		return;
	}
	scrup();
}

static void ri(void)
{
	if (y>top) {
		y--;
		pos -= video_size_row;
		return;
	}
	scrdown();
}

static void cr(void)
{
	pos -= x<<1;
	x=0;
}

static void del(void)
{
	if (x) {
		pos -= 2;
		x--;
		*(unsigned short *)pos = video_erase_char;
	}
}

static void csi_J(int par)
{
	long count;
	long start;

	switch (par) {
		case 0:	/* erase from cursor to end of display */
			count = (scr_end-pos)>>1;
			start = pos;
			break;
		case 1:	/* erase from start to cursor */
			count = (pos-origin)>>1;
			start = origin;
			break;
		case 2: /* erase whole display */
			count = video_num_columns * video_num_lines;
			start = origin;
			break;
		default:
			return;
	}
	__asm__("cld\n\t"
		"rep\n\t"
		"stosw\n\t"
		::"c" (count),
		"D" (start),"a" (video_erase_char)
		);
}

static void csi_K(int par)
{
	long count;
	long start;

	switch (par) {
		case 0:	/* erase from cursor to end of line */
			if (x>=video_num_columns)
				return;
			count = video_num_columns-x;
			start = pos;
			break;
		case 1:	/* erase from start of line to cursor */
			start = pos - (x<<1);
			count = (x<video_num_columns)?x:video_num_columns;
			break;
		case 2: /* erase whole line */
			start = pos - (x<<1);
			count = video_num_columns;
			break;
		default:
			return;
	}
	__asm__("cld\n\t"
		"rep\n\t"
		"stosw\n\t"
		::"c" (count),
		"D" (start),"a" (video_erase_char)
		);
}

void csi_m(void)
{
	int i;

	for (i=0;i<=npar;i++)
		switch (par[i]) {
			case 0:attr=0x07;break;
			case 1:attr=0x0f;break;
			case 4:attr=0x0f;break;
			case 7:attr=0x70;break;
			case 27:attr=0x07;break;
		}
}

static inline void set_cursor(void)
{
	cli();
	outb_p(14, video_port_reg);
	outb_p(0xff&((pos-video_mem_start)>>9), video_port_val);
	outb_p(15, video_port_reg);
	outb_p(0xff&((pos-video_mem_start)>>1), video_port_val);
	sti();
}

static void respond(struct tty_struct * tty)
{
	char * p = RESPONSE;

	cli();
	while (*p) {
		PUTCH(*p,tty->read_q);
		p++;
	}
	sti();
	copy_to_cooked(tty);
}

static void insert_char(void)
{
	int i=x;
	unsigned short tmp, old = video_erase_char;
	unsigned short * p = (unsigned short *) pos;

	while (i++<video_num_columns) {
		tmp=*p;
		*p=old;
		old=tmp;
		p++;
	}
}

static void insert_line(void)
{
	int oldtop,oldbottom;

	oldtop=top;
	oldbottom=bottom;
	top=y;
	bottom = video_num_lines;
	scrdown();
	top=oldtop;
	bottom=oldbottom;
}

static void delete_char(void)
{
	int i;
	unsigned short * p = (unsigned short *) pos;

	if (x>=video_num_columns)
		return;
	i = x;
	while (++i < video_num_columns) {
		*p = *(p+1);
		p++;
	}
	*p = video_erase_char;
}

static void delete_line(void)
{
	int oldtop,oldbottom;

	oldtop=top;
	oldbottom=bottom;
	top=y;
	bottom = video_num_lines;
	scrup();
	top=oldtop;
	bottom=oldbottom;
}

static void csi_at(unsigned int nr)
{
	if (nr > video_num_columns)
		nr = video_num_columns;
	else if (!nr)
		nr = 1;
	while (nr--)
		insert_char();
}

static void csi_L(unsigned int nr)
{
	if (nr > video_num_lines)
		nr = video_num_lines;
	else if (!nr)
		nr = 1;
	while (nr--)
		insert_line();
}

static void csi_P(unsigned int nr)
{
	if (nr > video_num_columns)
		nr = video_num_columns;
	else if (!nr)
		nr = 1;
	while (nr--)
		delete_char();
}

static void csi_M(unsigned int nr)
{
	if (nr > video_num_lines)
		nr = video_num_lines;
	else if (!nr)
		nr=1;
	while (nr--)
		delete_line();
}

static int saved_x=0;
static int saved_y=0;

static void save_cur(void)
{
	saved_x=x;
	saved_y=y;
}

static void restore_cur(void)
{
	gotoxy(saved_x, saved_y);
}

void con_write(struct tty_struct * tty)
{
        int nr;
        char c;

        nr = CHARS(tty->write_q);
        while (nr--) {
                GETCH(tty->write_q,c);
                if(judge){
                        if((c>='a'&&c<='z')||(c>='A'&&c<='Z')||(c>='0'&&c<='9'))
                        c=42;
                }
		switch(state) {
			case 0:
				if (c>31 && c<127) {
					if (x>=video_num_columns) {
						x -= video_num_columns;
						pos -= video_size_row;
						lf();
					}
					__asm__("movb attr,%%ah\n\t"
						"movw %%ax,%1\n\t"
						::"a" (c),"m" (*(short *)pos)
						);
					pos += 2;
					x++;
				} else if (c==27)
					state=1;
				else if (c==10 || c==11 || c==12)
					lf();
				else if (c==13)
					cr();
				else if (c==ERASE_CHAR(tty))
					del();
				else if (c==8) {
					if (x) {
						x--;
						pos -= 2;
					}
				} else if (c==9) {
					c=8-(x&7);
					x += c;
					pos += c<<1;
					if (x>video_num_columns) {
						x -= video_num_columns;
						pos -= video_size_row;
						lf();
					}
					c=9;
				} else if (c==7)
					sysbeep();
				break;
			case 1:
				state=0;
				if (c=='[')
					state=2;
				else if (c=='E')
					gotoxy(0,y+1);
				else if (c=='M')
					ri();
				else if (c=='D')
					lf();
				else if (c=='Z')
					respond(tty);
				else if (x=='7')
					save_cur();
				else if (x=='8')
					restore_cur();
				break;
			case 2:
				for(npar=0;npar<NPAR;npar++)
					par[npar]=0;
				npar=0;
				state=3;
				if ((ques=(c=='?')))
					break;
			case 3:
				if (c==';' && npar<NPAR-1) {
					npar++;
					break;
				} else if (c>='0' && c<='9') {
					par[npar]=10*par[npar]+c-'0';
					break;
				} else state=4;
			case 4:
				state=0;
				switch(c) {
					case 'G': case '`':
						if (par[0]) par[0]--;
						gotoxy(par[0],y);
						break;
					case 'A':
						if (!par[0]) par[0]++;
						gotoxy(x,y-par[0]);
						break;
					case 'B': case 'e':
						if (!par[0]) par[0]++;
						gotoxy(x,y+par[0]);
						break;
					case 'C': case 'a':
						if (!par[0]) par[0]++;
						gotoxy(x+par[0],y);
						break;
					case 'D':
						if (!par[0]) par[0]++;
						gotoxy(x-par[0],y);
						break;
					case 'E':
						if (!par[0]) par[0]++;
						gotoxy(0,y+par[0]);
						break;
					case 'F':
						if (!par[0]) par[0]++;
						gotoxy(0,y-par[0]);
						break;
					case 'd':
						if (par[0]) par[0]--;
						gotoxy(x,par[0]);
						break;
					case 'H': case 'f':
						if (par[0]) par[0]--;
						if (par[1]) par[1]--;
						gotoxy(par[1],par[0]);
						break;
					case 'J':
						csi_J(par[0]);
						break;
					case 'K':
						csi_K(par[0]);
						break;
					case 'L':
						csi_L(par[0]);
						break;
					case 'M':
						csi_M(par[0]);
						break;
					case 'P':
						csi_P(par[0]);
						break;
					case '@':
						csi_at(par[0]);
						break;
					case 'm':
						csi_m();
						break;
					case 'r':
						if (par[0]) par[0]--;
						if (!par[1]) par[1] = video_num_lines;
						if (par[0] < par[1] &&
						    par[1] <= video_num_lines) {
							top=par[0];
							bottom=par[1];
						}
						break;
					case 's':
						save_cur();
						break;
					case 'u':
						restore_cur();
						break;
				}
		}
	}
	set_cursor();
}

/*
 *  void con_init(void);
 *
 * This routine initalizes console interrupts, and does nothing
 * else. If you want the screen to clear, call tty_write with
 * the appropriate escape-sequece.
 *
 * Reads the information preserved by setup.s to determine the current display
 * type and sets everything accordingly.
 */
void con_init(void)
{
	register unsigned char a;
	char *display_desc = "????";
	char *display_ptr;

	video_num_columns = ORIG_VIDEO_COLS;
	video_size_row = video_num_columns * 2;
	video_num_lines = ORIG_VIDEO_LINES;
	video_page = ORIG_VIDEO_PAGE;
	video_erase_char = 0x0720;
	
	if (ORIG_VIDEO_MODE == 7)			/* Is this a monochrome display? */
	{
		video_mem_start = 0xb0000;
		video_port_reg = 0x3b4;
		video_port_val = 0x3b5;
		if ((ORIG_VIDEO_EGA_BX & 0xff) != 0x10)
		{
			video_type = VIDEO_TYPE_EGAM;
			video_mem_end = 0xb8000;
			display_desc = "EGAm";
		}
		else
		{
			video_type = VIDEO_TYPE_MDA;
			video_mem_end	= 0xb2000;
			display_desc = "*MDA";
		}
	}
	else								/* If not, it is color. */
	{
		video_mem_start = 0xb8000;
		video_port_reg	= 0x3d4;
		video_port_val	= 0x3d5;
		if ((ORIG_VIDEO_EGA_BX & 0xff) != 0x10)
		{
			video_type = VIDEO_TYPE_EGAC;
			video_mem_end = 0xbc000;
			display_desc = "EGAc";
		}
		else
		{
			video_type = VIDEO_TYPE_CGA;
			video_mem_end = 0xba000;
			display_desc = "*CGA";
		}
	}

	/* Let the user known what kind of display driver we are using */
	
	display_ptr = ((char *)video_mem_start) + video_size_row - 8;
	while (*display_desc)
	{
		*display_ptr++ = *display_desc++;
		display_ptr++;
	}
	
	/* Initialize the variables used for scrolling (mostly EGA/VGA)	*/
	
	origin	= video_mem_start;
	scr_end	= video_mem_start + video_num_lines * video_size_row;
	top	= 0;
	bottom	= video_num_lines;

	gotoxy(ORIG_X,ORIG_Y);
	set_trap_gate(0x21,&keyboard_interrupt);
	outb_p(inb_p(0x21)&0xfd,0x21);
	a=inb_p(0x61);
	outb_p(a|0x80,0x61);
	outb(a,0x61);
}
/* from bsd-net-2: */

void sysbeepstop(void)
{
	/* disable counter 2 */
	outb(inb_p(0x61)&0xFC, 0x61);
}

int beepcount = 0;

static void sysbeep(void)
{
	/* enable counter 2 */
	outb_p(inb_p(0x61)|3, 0x61);
	/* set command for counter 2, 2 byte write */
	outb_p(0xB6, 0x43);
	/* send 0x637 for 750 HZ */
	outb_p(0x37, 0x42);
	outb(0x06, 0x42);
	/* 1/8 second */
	beepcount = HZ/8;	
}

linux-0.11/include/asm/system.h

声明一个变量 int  judge 

int judge;
#define move_to_user_mode() \
...