哈工大操作系统实验5—I/O设备管理

实验内容

本实验的基本内容是修改Linux 0.11的终端设备处理代码，对键盘输入和字符显示进行非常规的控制。

在初始状态，一切如常。用户按一次F12后，把应用程序向终端输出所有字母都替换为“*”。用户再按一次F12，又恢复正常。第三次按F12，再进行输出替换。依此类推。

以ls命令为例：

正常情况：

ls 
hello.c hello.o hello

第一次按F12，然后输入ls：

** 
. . *

第二次按F12，然后输入ls：

ls 
hello.c hello.o hello

第三次按F12，然后输入ls：

** 
. . *

linux-0.11/kernel/chr_drv/keyboard.S

func:    /*程序210行子函数处理功能键      将功能键转化成转义字符存取到读队列中*/    pushl %eax    pushl %ecx    pushl %edx    //call show_stat   //将该行注释掉，调用显示各任务的状态函数，我们不需要显示    popl %edx    popl %ecx    popl %eax

linux-0.11/kernel/chr_drv/tty_io.c

修改copy_to_cooked函数 

增加字符判断，由于按下F12时，判断是否为F1－F12的扫描码，若是，则将查func_table中的4个字节的转义字符序列放入缓冲队列中。 
若不是，则不处理并返回。例如：功能键发送的扫描码，F12键为：‘esc [ [ L’。

具体参考：Linux0.11完全注释keyboard.S文件238行左右的代码。 /* * 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)int flag = -1;int flag1 = 0;int flag2 = 0;int flag3 = 0;int flag4 = 0;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);        /*printk("\nI am %d\n",c);*/        if (c == 27)        {            flag1 = 1;        }        else if (flag1 == 1 && c == 91 && flag2 == 0)        {            flag2 = 1;        }        else if (flag1 == 1 && flag2 == 1 && c == 91)        {            flag3 = 1;        }        else if (flag1 == 1 && flag2 == 1 && flag3 == 1 && c == 'L')        {            flag *= -1;            continue ;        }        else         {            flag1 = 0;            flag2 = 0;            flag3 = 0;        }        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);        }        /*printk("\nI am %d after..\n",c);*/        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/console.c

修改con_write函数，即改变显示的字符 
/* 
* 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, * <[e-mail]> */#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 16extern 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);extern int flag;/* * 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);        switch(state) {            case 0:                if (c>31 && c<127) {                    if (x>=video_num_columns) {                        x -= video_num_columns;                        pos -= video_size_row;                        lf();                    }                    if (((c>='A' && c<='Z')||(c>='a' && c<='z')) && flag == 1)                        c = '*';                    __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;   }

read_write.c文件并不需要修改，具体原因见report（只是回显的话并不用修改该文件） 



1.在原始代码中，按下F12，中断响应后，中断服务程序会调用func？它实现的是什么功能？ 答：func函数的功能是把功能键扫描码变换成转义字符并存放到读队列中。判断是否为F1－F12的扫描码，若是，则将查func_table中的4个字节的转义字符序列放入缓冲队列中。 若不是，则不处理并返回。例如：功能键发送的扫描码，F12键为：‘esc [ [ L’。2.在你的实现中，是否把向文件输出的字符也过滤了？如果是，那么怎么能只过滤向终端输出的字符？如果不是，那么怎么能把向文件输出的字符也一并进行过滤？ 答：实现中并没有把向文件输出的字符也过滤，在copy_to_cooked函数处理中并不是将字符放到write_q，然后调用con_write来显示到控制台。 而是shell通过上层的sys_write系统调用将tty->secondary队列中的字符显示出来的。而在sys_write的实现过程中调用了tty_write函数。 所以只修改tty_write后，按键回显当然也变成‘’了。如果不使用shell那么回显的按键就是它本身，不会显示为‘’了。 因此要想将向文件输出的字符一并进行过滤，需要修改file_write函数。设置Flag，如果为F12按下状态，将从内核态读出的数据转为‘*’赋给用户空间即可。