help.c

操作系统源代码

/* Copyright (c) 1985 Ceriel J.H. Jacobs */

#ifndef lint
static char rcsid[] = "$Header: help.c,v 7.2 88/04/29 11:45:22 ceriel Exp $";
#endif

#define _HELP_
#include "in_all.h"
#include "help.h"
#include "machine.h"
#include "commands.h"
#include "keys.h"
#include "output.h"
#include "prompt.h"
#include "main.h"
#include "display.h"
#include "term.h"
#include "options.h"

static int h_cnt;		/* Count # of lines */
static struct state *origin;	/* Keep track of startstate */

/*
 * Print a key sequence.
 * We arrived at an endstate. The s_next link in the state structure now
 * leads us from "origin" to the current state, so that we can print the key
 * sequence easily.
 */

STATIC VOID
pr_comm() {
	register struct state *p = origin;
	register char *pb;
	register int c;
	char buf[30];
	register int i = 0;	/* How many characters printed? */

	pb = buf;
	for (;;) {
		c = p->s_char & 0177;
		if (c < ' ' || c == 0177) {
			/*
			 * Will take an extra position
			 */
			i++;
		}
		*pb++ = c;
		i++;
		if (!p->s_match) break;
		p = p->s_next;
	}
	do {
		*pb++ = ' ';
	} while (++i < 12);
	*pb = 0;
	cputline(buf);
}

/*
 * Print out a description of the keymap. This is done, by temporarily using
 * the s_next field in the state structure indicate the state matching the
 * next character, so that we can walk from "origin" to an endstate.
 */

STATIC VOID
pr_mach(currstate, back) register struct state *currstate, *back; {
	struct state *save;

	while (currstate) {
		if (interrupt) break;
		if (back) {
			save = back->s_next;	/* Save original link */
			back->s_next = currstate;
		}
		if (!currstate->s_match) {
			/*
			 * End state, print command
			 */
			pr_comm();
			putline(commands[currstate->s_cnt].c_descr);
			putline("\r\n");
			if (++h_cnt >= maxpagesize) {
				ret_to_continue();
				h_cnt = 0;
			}
		}
		else pr_mach(currstate->s_match, currstate);
		currstate = currstate->s_next;
		if (back) back->s_next = save;	/* restore */
		else origin = currstate;
	}
}

/*ARGSUSED*/
int
do_help(i) long i; {	/* The help command */

	startcomm = 0;
	h_cnt = 2;
	putline("\r\nSummary of yap commands:\r\n");
	origin = currmap->k_mach;
	pr_mach(currmap->k_mach, (struct state *) 0);
	if (h_cnt) {
		ret_to_continue();
	}
	if (!hardcopy && scr_info.currentpos) redraw(1);
}