kernel源码（十八）字符设备-console.c

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源码

/*
 *  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);

/*
 * 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)
                    :"cx","di","si");
                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)
                    :"cx","di");
            }
            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))
                :"cx","di","si");
        }
    }
    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))
            :"cx","di","si");
    }
}

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)
            :"ax","cx","di","si");
    }
    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)
            :"ax","cx","di","si");
    }
}

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 __asm__("cx");
    long start __asm__("di");

    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)
        :"cx","di");
}

static void csi_K(int par)
{
    long count __asm__("cx");
    long start __asm__("di");

    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)
        :"cx","di");
}

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();
                    }
                    __asm__("movb _attr,%%ah\n\t"
                        "movw %%ax,%1\n\t"
                        ::"a" (c),"m" (*(short *)pos)
                        :"ax");
                    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;    
}

一些常量

#define ORIG_X            (*(unsigned char *)0x90000) //初始光标列号
#define ORIG_Y            (*(unsigned char *)0x90001) //初始光标行号
#define ORIG_VIDEO_PAGE         (*(unsigned short *)0x90004) //显示的页面
#define ORIG_VIDEO_MODE        ((*(unsigned short *)0x90006) & 0xff) //显示模式
#define ORIG_VIDEO_COLS     (((*(unsigned short *)0x90006) & 0xff00) >> 8) //字符的列数
#define ORIG_VIDEO_LINES    (25) //显示的行号
#define ORIG_VIDEO_EGA_AX    (*(unsigned short *)0x90008)
#define ORIG_VIDEO_EGA_BX    (*(unsigned short *)0x9000a) //内存大小和彩色模式
#define ORIG_VIDEO_EGA_CX    (*(unsigned short *)0x9000c) //显示卡的特性参数

#define VIDEO_TYPE_MDA        0x10    /* Monochrome Text Display    */单色文本
#define VIDEO_TYPE_CGA        0x11    /* CGA Display             */ CGA
#define VIDEO_TYPE_EGAM        0x20    /* EGA/VGA in Monochrome Mode    */ EGA或者VGA的单色模式
#define VIDEO_TYPE_EGAC        0x21    /* EGA/VGA in Color Mode    */ EGA或者VGA的彩色模式

#define NPAR 16 //转移序列中最大参数的个数

键盘中断处理程序

 extern void keyboard_interrupt(void); 

static unsigned char    video_type; //当前使用的显示类型        /* Type of display being used    */
static unsigned long    video_num_columns; //屏幕文本列数    /* Number of text columns    */
static unsigned long    video_size_row; //屏幕每行使用的字节数        /* Bytes per row        */
static unsigned long    video_num_lines; //屏幕文本的行数    /* Number of test lines        */
static unsigned char    video_page; //初始显示的页面        /* Initial video page        */
static unsigned long    video_mem_start; //显示内存的起始的地址    /* Start of video RAM        */
static unsigned long    video_mem_end; //显示内存的结束地址       /* End of video RAM (sort of)    */
static unsigned short    video_port_reg; //显示控制器索引寄存器的端口        /* Video register select port    */
static unsigned short    video_port_val; //显示控制数据寄存器的端口        /* Video register value port    */
static unsigned short    video_erase_char; //擦除字符的属性以及字符    /* Char+Attrib to erase with    */

static unsigned long    origin; //EGA或者VGA快速卷屏的。卷屏起始内存的地址        /* Used for EGA/VGA fast scroll    */
static unsigned long    scr_end; //滚屏末端内存的地址    /* Used for EGA/VGA fast scroll    */
static unsigned long    pos;//光标
static unsigned long    x,y;//当前的列号和行号
static unsigned long    top,bottom; //滚动的时候顶行的行号和底行的行号
static unsigned long    state=0; //nsr转义字符序列中表示状态
static unsigned long    npar,par[NPAR]; //npar表示转义字符序列参数的个数。par是转义字符序列参数数组
static unsigned long    ques=0; //？字符的标志
static unsigned char    attr=0x07; //字符的属性，0x07表示黑底白字

系统蜂鸣的函数

 static void sysbeep(void); 

csi是控制字符引导码。主机通过发送设备属性控制序列，要求终端应答一个设备属性控制序列。终端就发送'\033[?1;2c'来响应主机。

/*
 * this is what the terminal answers to a ESC-Z or csi0c
 * query (= vt100 response).
 */
#define RESPONSE "\033[?1;2c" //代表ESC[?1;2c表示终端是高级视频的终端

根据新的行号和列号，定位新的内存的位置pos

static inline void gotoxy(unsigned int new_x,unsigned int new_y)
{
    if (new_x > video_num_columns || new_y >= video_num_lines) //行号和列号是否超过范围
        return;
    x=new_x;
    y=new_y;
    pos=origin + y*video_size_row + (x<<1); //行号和列号对应的内存的地址，x左移1位表示其除以2，因为一列用两个字节表示
}

设置滚屏的起始显示内存的地址

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();
}

待续...

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