console.c

一份精简的linux内核源代码

/*
 *  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,
 * <[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（setup.s） at boot-time:
 */

#define ORIG_X			(*(unsigned char *)0x90000)           /* 初始关标列号*/
#define ORIG_Y			(*(unsigned char *)0x90001)           /* 初始关标行号*/
#define ORIG_VIDEO_PAGE		(*(unsigned short *)0x90004)      /*显示页面*/
#define ORIG_VIDEO_MODE		((*(unsigned short *)0x90006) & 0xff)   /* 显示模式*/
#define ORIG_VIDEO_COLS 	(((*(unsigned short *)0x90006) & 0xff00) >> 8) /* 字符列数*/
#define ORIG_VIDEO_LINES	(25)                                /*显示行数*/
#define ORIG_VIDEO_EGA_AX	(*(unsigned short *)0x90008)
#define ORIG_VIDEO_EGA_BX	(*(unsigned short *)0x9000a)     /* 显存大小*/
#define ORIG_VIDEO_EGA_CX	(*(unsigned short *)0x9000c)       /* 显卡特性参数*/

#define VIDEO_TYPE_MDA		0x10	/* Monochrome（单色） 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 /* 转义字符序列中最大参数个数*/

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 text 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	*//* 擦除字符属性及字符	*/

static unsigned long	origin;		/* Used for EGA/VGA fast scroll	*//* 屏幕起始地址（orgin-video_mem_start即为）	*/
static unsigned long	scr_end;	/* Used for EGA/VGA fast scroll	*//* 屏幕末端地址	*/
static unsigned long	pos;   /* 当前光标对应显示内存位置*/
static unsigned long	x,y;    /* 目前光标位置	*/
static unsigned long	top,bottom; /* 屏幕中顶行行号，底行行号（top是相对于orgin的）	*/
static unsigned long	state=0;  /* ANSI转义字符序列处理状态	*/
static unsigned long	npar,par[NPAR]; /* ANSI转义字符序列参数和参数个数*/
static unsigned long	ques=0;    /* 收到问号字符标志	*/
static unsigned char	attr=0x07;   /* 字符属性（黑底白子）	*/

static void sysbeep(void);   /* 系统蜂鸣函数*/

/*
 * this is what the terminal answers to a ESC-Z or csi0c
 * query (= vt100 response).
 */
#define RESPONSE "\033[?1;2c"  /* 表示终端是高级视频终端（应答主机发问的应答序列）	*/

/* NOTE! gotoxy thinks x==video_num_columns is ok */
static inline void gotoxy(unsigned int new_x,unsigned int new_y)/*更新光标当前所在位置和光标对应的显存位置pos。*/
{
	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) /* 设置滚屏起始显存地址（在屏幕上显示数据的实质）	*/ /* 屏幕上一个字符用2个字节表示*/
{
	cli();
	outb_p(12, video_port_reg);                     /* 选择显示控制数据寄存器r12*/
	outb_p(0xff&((origin-video_mem_start)>>9), video_port_val); /* 向r12中写入卷屏起始地址高字节*/
	outb_p(13, video_port_reg);                     /* 选择显示控制数据寄存器r13*/
	outb_p(0xff&((origin-video_mem_start)>>1), video_port_val); /* 向r13中写入卷屏起始地址底字节*/
	sti();
}

static void scrup(void)  /* 向上卷动一行*/
{
	if (video_type == VIDEO_TYPE_EGAC || video_type == VIDEO_TYPE_EGAM) /* 显卡类型*/
	{
		if (!top && bottom == video_num_lines) {/* 整屏窗口向下移动（显存中的数据不动，仅仅是屏幕在下移）*/
			origin += video_size_row;
			pos += video_size_row;
			scr_end += video_size_row;
			if (scr_end > video_mem_end) {/* 下移之后越界，则将屏幕中的数据移置显存开始位置*/
				__asm__("cld\n\t"
					"rep\n\t"
					"movsl\n\t"   /*move data from edi(S) to esi(D)*/
					"movl _video_num_columns,%1\n\t"
					"rep\n\t"
					"stosw"   /*在新行上填空格*/
					::"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 { /*下移之后未越界，则将新进入屏幕的一行填成空格*/
				__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();/* 设置显示控制器中显示的内容*/
		} else { /*非整屏移动（屏幕不动，仅移动显存中的数据）*/
			__asm__("cld\n\t"
				"rep\n\t"
				"movsl\n\t"  /*将top--botton之间的数据上移一行*/
				"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)    /* 向下卷动一行*/
{
	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)/*换行*/
{
	if (y+1<bottom) {
		y++;
		pos += video_size_row;
		return;
	}
	scrup();
}

static void ri(void)/*反换行*/
{
	if (y>top) {
		y--;
		pos -= video_size_row;
		return;
	}
	scrdown();
}

static void cr(void) /*回行首*/
{
	pos -= x<<1;
	x=0;
}

static void del(void) /*删除一字符*/
{
	if (x) {
		pos -= 2;
		x--;
		*(unsigned short *)pos = video_erase_char;
	}
}

static void csi_J(int par)/*删除屏幕上的相关数据*/
{
	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)/*类上*/
{
	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) /*设置显示字符属性*/
{
	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)/*设置显示光标*/
{
	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)/*将RESPONSE放入读队列及辅助队列中*/
{
	char * p = RESPONSE;

	cli();
	while (*p) { /*逐字的放入read_q队列*/
		PUTCH(*p,tty->read_q);
		p++;
	}
	sti();
	copy_to_cooked(tty);/*放入辅助队列*/
}

static void insert_char(void)/*插入空格*/
{
	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)/*插入行*/
{
	int oldtop,oldbottom;

	oldtop=top;
	oldbottom=bottom;
	top=y;