### 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,
* <g-hunt@ee.utah.edu>
*/
#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);
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。
markdown在CSDN上的可读性没有正常网页编辑好，下篇还是用网页编辑，这篇就这样。
