console.c

一份精简的linux内核源代码

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

static void delete_char(void)/*删除一个字符*/
{
	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)/*删除行*/
{
	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)/*插入nr个字符*/
{
	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)/*插入nr行*/
{
	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)/*删除nr个字符*/
{
	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)/*删除nr行*/
{
	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)/*保存光标*/
{
	saved_x=x;
	saved_y=y;
}

static void restore_cur(void)/*恢复保存的光标位置*/
{
	gotoxy(saved_x, saved_y);
}

void con_write(struct tty_struct * tty)/*控制台写函数(p362)*/
{
	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) /*控制台初始化：显示器显卡参数设置，开键盘中断*/
{
	register unsigned char a;
	char *display_desc = "????";
	char *display_ptr;

	video_num_columns = ORIG_VIDEO_COLS;/*显示器显示字符列数*/
	video_size_row = video_num_columns * 2;/*每行字符需使用的字节数*/
	video_num_lines = ORIG_VIDEO_LINES;/*显示器显示字符行数*/
	video_page = ORIG_VIDEO_PAGE;/*当前显示页面*/
	video_erase_char = 0x0720;/*擦除字符（0x20是字符，0x07是属性）*/
 /*判断是显卡及显示器类型*/	
	if (ORIG_VIDEO_MODE == 7)			/*判断是否是单色显示器*/
	{                                  /*为单色的情况*/
		video_mem_start = 0xb0000;    /*设置单色显示器显存起始地址*/
		video_port_reg = 0x3b4;    /*设置单色显示器索引寄存器端口号*/
		video_port_val = 0x3b5;    /*设置单色显示器数据寄存器端口*/
		if ((ORIG_VIDEO_EGA_BX & 0xff) != 0x10)    /*判断是单色显卡还是彩色显卡*/
		{
			video_type = VIDEO_TYPE_EGAM;    /*设置显示类型（EGA单色）*/
			video_mem_end = 0xb8000;    /*设置显示内存末端地址*/
			display_desc = "EGAm";    /*设置显示描述字符串*/
		}
		else
		{
			video_type = VIDEO_TYPE_MDA;    /*设置显示类型（MDA单色）*/
			video_mem_end	= 0xb2000;   /*设置显示内存末端地址*/
			display_desc = "*MDA";    /*设置显示描述字符串*/
		}
	}
	else								/* If not, it is color. */
	{                                 /*为彩色的情况*/
		video_mem_start = 0xb8000;/*设置彩色显示器显存起始地址*/
		video_port_reg	= 0x3d4;/*设置彩色显示器索引寄存器端口号*/
		video_port_val	= 0x3d5; /*设置彩色显示器数据寄存器端口*/
		if ((ORIG_VIDEO_EGA_BX & 0xff) != 0x10) /*判断是单色显卡还是彩色显卡*/
		{
			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 */
	/*在屏幕右上角显示描述字符串（好像不能显示？）*/
	display_ptr = ((char *)video_mem_start) + video_size_row - 8;  /*直接将字符串写道显存中相应的位置*/
	while (*display_desc)
	{
		*display_ptr++ = *display_desc++; /*复制描述字符串*/
		display_ptr++;
	}
	
	/* Initialize the variables used for scrolling (mostly EGA/VGA)	*/
	 /*初始化用于滚屏的变量*/
	origin	= video_mem_start; /*滚屏起始显示内存地址*/
	scr_end	= video_mem_start + video_num_lines * video_size_row; /*结束地址*/
	top	= 0; /*最顶行号*/
	bottom	= video_num_lines; /*最底行号*/

	gotoxy(ORIG_X,ORIG_Y); /*初始化光标当前所在位置和光标对应的内存位置pos。*/
	set_trap_gate(0x21,&keyboard_interrupt); /*设置键盘中断*/
	outb_p(inb_p(0x21)&0xfd,0x21);  /*取消8259A对键盘中断的屏蔽*/
	a=inb_p(0x61);               /*读取键盘端口*/
	outb_p(a|0x80,0x61); /*设置禁止键盘工作*/
	outb(a,0x61);        /*再允许键盘工作，用以复位键盘*/
}
/* 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;	
}