if (cons->c_column > scr_width) cons->c_column = scr_width;  if (cons->c_row < 0) cons->c_row = 0;  if (cons->c_row >= scr_lines) cons->c_row = scr_lines - 1;  cur = cons->c_org + cons->c_row * scr_width + cons->c_column;  if (cur != cons->c_cur) {	if (cons == curcons) set_6845(CURSOR, cur);	cons->c_cur = cur;  }}/*===========================================================================* *				parse_escape				     * *===========================================================================*/PRIVATE void parse_escape(cons, c)register console_t *cons;	/* pointer to console struct */char c;				/* next character in escape sequence */{/* The following ANSI escape sequences are currently supported. * If n and/or m are omitted, they default to 1. *   ESC [nA moves up n lines *   ESC [nB moves down n lines *   ESC [nC moves right n spaces *   ESC [nD moves left n spaces *   ESC [m;nH" moves cursor to (m,n) *   ESC [J clears screen from cursor *   ESC [K clears line from cursor *   ESC [nL inserts n lines ar cursor *   ESC [nM deletes n lines at cursor *   ESC [nP deletes n chars at cursor *   ESC [n@ inserts n chars at cursor *   ESC [nm enables rendition n (0=normal, 4=bold, 5=blinking, 7=reverse) *   ESC M scrolls the screen backwards if the cursor is on the top line */  switch (cons->c_esc_state) {    case 1:			/* ESC seen */	cons->c_esc_intro = '\0';	cons->c_esc_parmp = bufend(cons->c_esc_parmv);	do {		*--cons->c_esc_parmp = 0;	} while (cons->c_esc_parmp > cons->c_esc_parmv);	switch (c) {	    case '[':	/* Control Sequence Introducer */		cons->c_esc_intro = c;		cons->c_esc_state = 2;		break;	    case 'M':	/* Reverse Index */		do_escape(cons, c);		break;	    default:		cons->c_esc_state = 0;	}	break;    case 2:			/* ESC [ seen */	if (c >= '0' && c <= '9') {		if (cons->c_esc_parmp < bufend(cons->c_esc_parmv))			*cons->c_esc_parmp = *cons->c_esc_parmp * 10 + (c-'0');	} else	if (c == ';') {		if (cons->c_esc_parmp < bufend(cons->c_esc_parmv))			cons->c_esc_parmp++;	} else {		do_escape(cons, c);	}	break;  }}/*===========================================================================* *				do_escape				     * *===========================================================================*/PRIVATE void do_escape(cons, c)register console_t *cons;	/* pointer to console struct */char c;				/* next character in escape sequence */{  int value, n;  unsigned src, dst, count;  int *parmp;  /* Some of these things hack on screen RAM, so it had better be up to date */  flush(cons);  if (cons->c_esc_intro == '\0') {	/* Handle a sequence beginning with just ESC */	switch (c) {	    case 'M':		/* Reverse Index */		if (cons->c_row == 0) {			scroll_screen(cons, SCROLL_DOWN);		} else {			cons->c_row--;		}		flush(cons);		break;	    default: break;	}  } else  if (cons->c_esc_intro == '[') {	/* Handle a sequence beginning with ESC [ and parameters */	value = cons->c_esc_parmv[0];	switch (c) {	    case 'A':		/* ESC [nA moves up n lines */		n = (value == 0 ? 1 : value);		cons->c_row -= n;		flush(cons);		break;	    case 'B':		/* ESC [nB moves down n lines */		n = (value == 0 ? 1 : value);		cons->c_row += n;		flush(cons);		break;	    case 'C':		/* ESC [nC moves right n spaces */		n = (value == 0 ? 1 : value);		cons->c_column += n;		flush(cons);		break;	    case 'D':		/* ESC [nD moves left n spaces */		n = (value == 0 ? 1 : value);		cons->c_column -= n;		flush(cons);		break;	    case 'H':		/* ESC [m;nH" moves cursor to (m,n) */		cons->c_row = cons->c_esc_parmv[0] - 1;		cons->c_column = cons->c_esc_parmv[1] - 1;		flush(cons);		break;	    case 'J':		/* ESC [sJ clears in display */		switch (value) {		    case 0:	/* Clear from cursor to end of screen */			count = scr_size - (cons->c_cur - cons->c_org);			dst = cons->c_cur;			break;		    case 1:	/* Clear from start of screen to cursor */			count = cons->c_cur - cons->c_org;			dst = cons->c_org;			break;		    case 2:	/* Clear entire screen */			count = scr_size;			dst = cons->c_org;			break;		    default:	/* Do nothing */			count = 0;			dst = cons->c_org;		}		blank_color = cons->c_blank;		mem_vid_copy(BLANK_MEM, dst, count);		break;	    case 'K':		/* ESC [sK clears line from cursor */		switch (value) {		    case 0:	/* Clear from cursor to end of line */			count = scr_width - cons->c_column;			dst = cons->c_cur;			break;		    case 1:	/* Clear from beginning of line to cursor */			count = cons->c_column;			dst = cons->c_cur - cons->c_column;			break;		    case 2:	/* Clear entire line */			count = scr_width;			dst = cons->c_cur - cons->c_column;			break;		    default:	/* Do nothing */			count = 0;			dst = cons->c_cur;		}		blank_color = cons->c_blank;		mem_vid_copy(BLANK_MEM, dst, count);		break;	    case 'L':		/* ESC [nL inserts n lines at cursor */		n = value;		if (n < 1) n = 1;		if (n > (scr_lines - cons->c_row))			n = scr_lines - cons->c_row;		src = cons->c_org + cons->c_row * scr_width;		dst = src + n * scr_width;		count = (scr_lines - cons->c_row - n) * scr_width;		vid_vid_copy(src, dst, count);		blank_color = cons->c_blank;		mem_vid_copy(BLANK_MEM, src, n * scr_width);		break;	    case 'M':		/* ESC [nM deletes n lines at cursor */		n = value;		if (n < 1) n = 1;		if (n > (scr_lines - cons->c_row))			n = scr_lines - cons->c_row;		dst = cons->c_org + cons->c_row * scr_width;		src = dst + n * scr_width;		count = (scr_lines - cons->c_row - n) * scr_width;		vid_vid_copy(src, dst, count);		blank_color = cons->c_blank;		mem_vid_copy(BLANK_MEM, dst + count, n * scr_width);		break;	    case '@':		/* ESC [n@ inserts n chars at cursor */		n = value;		if (n < 1) n = 1;		if (n > (scr_width - cons->c_column))			n = scr_width - cons->c_column;		src = cons->c_cur;		dst = src + n;		count = scr_width - cons->c_column - n;		vid_vid_copy(src, dst, count);		blank_color = cons->c_blank;		mem_vid_copy(BLANK_MEM, src, n);		break;	    case 'P':		/* ESC [nP deletes n chars at cursor */		n = value;		if (n < 1) n = 1;		if (n > (scr_width - cons->c_column))			n = scr_width - cons->c_column;		dst = cons->c_cur;		src = dst + n;		count = scr_width - cons->c_column - n;		vid_vid_copy(src, dst, count);		blank_color = cons->c_blank;		mem_vid_copy(BLANK_MEM, dst + count, n);		break;	    case 'm':		/* ESC [nm enables rendition n */		for (parmp = cons->c_esc_parmv; parmp <= cons->c_esc_parmp				&& parmp < bufend(cons->c_esc_parmv); parmp++) {			if (cons->c_reverse) {				/* Unswap fg and bg colors */				cons->c_attr =	((cons->c_attr & 0x7000) >> 4) |						((cons->c_attr & 0x0700) << 4) |						((cons->c_attr & 0x8800));			}			switch (n = *parmp) {			    case 0:	/* NORMAL */				cons->c_attr = cons->c_blank = BLANK_COLOR;				cons->c_reverse = FALSE;				break;			    case 1:	/* BOLD  */				/* Set intensity bit */				cons->c_attr |= 0x0800;				break;			    case 4:	/* UNDERLINE */				if (color) {					/* Change white to cyan, i.e. lose red					 */					cons->c_attr = (cons->c_attr & 0xBBFF);				} else {					/* Set underline attribute */					cons->c_attr = (cons->c_attr & 0x99FF);				}				break;			    case 5:	/* BLINKING */				/* Set the blink bit */				cons->c_attr |= 0x8000;				break;			    case 7:	/* REVERSE */				cons->c_reverse = TRUE;				break;			    default:	/* COLOR */				if (n == 39) n = 37;	/* set default color */				if (n == 49) n = 40;				if (!color) {					/* Don't mess up a monochrome screen */				} else				if (30 <= n && n <= 37) {					/* Foreground color */					cons->c_attr =						(cons->c_attr & 0xF8FF) |						(ansi_colors[(n - 30)] << 8);					cons->c_blank =						(cons->c_blank & 0xF8FF) |						(ansi_colors[(n - 30)] << 8);				} else				if (40 <= n && n <= 47) {					/* Background color */					cons->c_attr =						(cons->c_attr & 0x8FFF) |						(ansi_colors[(n - 40)] << 12);					cons->c_blank =						(cons->c_blank & 0x8FFF) |						(ansi_colors[(n - 40)] << 12);				}			}			if (cons->c_reverse) {				/* Swap fg and bg colors */				cons->c_attr =	((cons->c_attr & 0x7000) >> 4) |						((cons->c_attr & 0x0700) << 4) |						((cons->c_attr & 0x8800));			}		}		break;	}  }  cons->c_esc_state = 0;}/*===========================================================================* *				set_6845				     * *===========================================================================*/PRIVATE void set_6845(reg, val)int reg;			/* which register pair to set */unsigned val;			/* 16-bit value to set it to */{/* Set a register pair inside the 6845. * Registers 12-13 tell the 6845 where in video ram to start * Registers 14-15 tell the 6845 where to put the cursor */  pvb_pair_t char_out[4];  pv_set(char_out[0], vid_port + INDEX, reg);	/* set index register */  pv_set(char_out[1], vid_port + DATA, (val>>8) & BYTE);    /* high byte */  pv_set(char_out[2], vid_port + INDEX, reg + 1);	    /* again */  pv_set(char_out[3], vid_port + DATA, val&BYTE);	    /* low byte */  sys_voutb(char_out, 4);			/* do actual output */}/*===========================================================================* *				get_6845				     * *===========================================================================*/PRIVATE void get_6845(reg, val)int reg;			/* which register pair to set */unsigned *val;			/* 16-bit value to set it to */{  char v1, v2;/* Get a register pair inside the 6845.  */  sys_outb(vid_port + INDEX, reg);   sys_inb(vid_port + DATA, &v1);   sys_outb(vid_port + INDEX, reg+1);   sys_inb(vid_port + DATA, &v2);   *val = (v1 << 8) | v2;}/*===========================================================================* *				beep					     * *===========================================================================*/PRIVATE void beep(){/* Making a beeping sound on the speaker (output for CRTL-G). * This routine works by turning on the bits 0 and 1 in port B of the 8255 * chip that drive the speaker. */  static timer_t tmr_stop_beep;  pvb_pair_t char_out[3];  clock_t now;  int port_b_val, s;    /* Fetch current time in advance to prevent beeping delay. */  if ((s=getuptime(&now)) != OK)  	panic("TTY","Console couldn't get clock's uptime.", s);  if (!beeping) {	/* Set timer channel 2, square wave, with given frequency. */        pv_set(char_out[0], TIMER_MODE, 0xB6);	        pv_set(char_out[1], TIMER2, (BEEP_FREQ >> 0) & BYTE);        pv_set(char_out[2], TIMER2, (BEEP_FREQ >> 8) & BYTE);        if (sys_voutb(char_out, 3)==OK) {        	if (sys_inb(PORT_B, &port_b_val)==OK &&        	    sys_outb(PORT_B, (port_b_val|3))==OK)        	    	beeping = TRUE;        }  }  /* Add a timer to the timers list. Possibly reschedule the alarm. */  tmrs_settimer(&tty_timers, &tmr_stop_beep, now+B_TIME, stop_beep, NULL);  if (tty_timers->tmr_exp_time != tty_next_timeout) {  	tty_next_timeout = tty_timers->tmr_exp_time;  	if ((s=sys_setalarm(tty_next_timeout, 1)) != OK)  		panic("TTY","Console couldn't set alarm.", s);