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/*
 * ¿ØÖÆ̨ÏÔʾ²Ù×÷
 */
/*
 *  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.
 */
/**********************
 * con_init con_write *
 **********************/
/*
 *  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> // ¶¨Òåtty_struct½á¹¹£¬´®ÐÐͨÐÅ·½ÃæµÄ²ÎÊýºÍ³£Á¿
#include <asm/io.h> // Ó²¼þ¶ÔÓ¦µÄ»ã±àioÖ¸Áî
#include <asm/system.h>
/*
 * These are set up by the setup-routine at boot-time:
 */
#define ORIG_X (*(unsigned char *)0x90000) // ¹â±êÁкÅ
#define ORIG_Y (*(unsigned char *)0x90001) // ¹â±êÐкÅ
#define ORIG_VIDEO_PAGE (*(unsigned short *)0x90004) // ÏÔʾҳÃæ
#define ORIG_VIDEO_MODE ((*(unsigned short *)0x90006) & 0xff) // ÏÔʾģʽ
#define ORIG_VIDEO_COLS (((*(unsigned short *)0x90006) & 0xff00) >> 8) // ×Ö·ûÁÐÊý
#define ORIG_VIDEO_LINES (25) // ×Ö·ûÐÐÊý
#define ORIG_VIDEO_EGA_AX (*(unsigned short *)0x90008) // £¿£¿
#define ORIG_VIDEO_EGA_BX (*(unsigned short *)0x9000a) // ÏÔʾÄÚ´æ´óСºÍÉ«²Êģʽ
#define ORIG_VIDEO_EGA_CX (*(unsigned short *)0x9000c) // ÏÔʾ¿¨ÌØÐÔ²ÎÊý
#define VIDEO_TYPE_MDA 0x10 /* Monochrome Text Display,µ¥É«Îı¾ */
#define VIDEO_TYPE_CGA 0x11