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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:
**
. . *
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
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) { }
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。
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原文地址:http://blog.csdn.net/wangjianyu0115/article/details/51247065