/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include <u.h>#include <libc.h>#include "expand.h" enum {	Black,	Blue,	Green,	Cyan,	Red,	Magenta,	Brown,	Grey, 	Bright = 0x08,	Blinking = 0x80, 	Yellow = Bright|Brown,	White = Bright|Grey,};	enum {	Width = 80*2,	Height = 25,	Attr = (Black<<4)|Grey,}; #define cga	((uchar*)0xB8000)int cgapos; static ucharcgaregr(int index){	outb(0x3D4, index);	return inb(0x3D4+1) & 0xFF;} static voidcgaregw(int index, int data){	outb(0x3D4, index);	outb(0x3D4+1, data);} static voidmovecursor(void){	cgaregw(0x0E, (cgapos/2>>8) & 0xFF);	cgaregw(0x0F, cgapos/2 & 0xFF);	cga[cgapos+1] = Attr;} voidcgaputc(int c){	int i;	uchar *p; 	if(c == '\n'){		cgapos = cgapos/Width;		cgapos = (cgapos+1)*Width;	}	else if(c == '\t'){		i = 8 - ((cgapos/2)&7);		while(i-->0)			cgaputc(' ');	}	else if(c == '\b'){		if(cgapos >= 2)			cgapos -= 2;		cgaputc(' ');		cgapos -= 2;	}	else{		cga[cgapos++] = c;		cga[cgapos++] = Attr;	}	if(cgapos >= Width*Height){		memmove(cga, &cga[Width], Width*(Height-1));		p = &cga[Width*(Height-1)];		for(i=0; i<Width/2; i++){			*p++ = ' ';			*p++ = Attr;		}		cgapos = Width*(Height-1);	}	movecursor();} voidcgainit(void){	cgapos = cgaregr(0x0E)<<8;	cgapos |= cgaregr(0x0F);	cgapos *= 2;}