tty_subr.c

基于组件方式开发操作系统的OSKIT源代码

/*
 * Copyright (c) 1994, David Greenman
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $\Id: tty_subr.c,v 1.10.4.4 1996/04/08 01:28:10 davidg Exp $
 */

/*
 * clist support routines
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/ioctl.h>
#include <sys/tty.h>
#include <sys/clist.h>
#include <sys/malloc.h>

struct cblock *cfreelist = 0;
int cfreecount = 0;
static int cslushcount;
static int ctotcount;

#ifndef INITIAL_CBLOCKS
#define	INITIAL_CBLOCKS 50
#endif

static void cblock_alloc_cblocks __P((int number));
static void cblock_free_cblocks __P((int number));

#define	CBLOCK_DIAG
#ifdef CBLOCK_DIAG
static void
cbstat()
{
	printf(
	"tot = %d (active = %d, free = %d (reserved = %d, slush = %d))\n",
	       ctotcount * CBSIZE, ctotcount * CBSIZE - cfreecount, cfreecount,
	       cfreecount - cslushcount * CBSIZE, cslushcount * CBSIZE);
}
#endif

/*
 * Called from init_main.c
 */
void
clist_init()
{
	/*
	 * Allocate an initial base set of cblocks as a 'slush'.
	 * We allocate non-slush cblocks with each initial ttyopen() and
	 * deallocate them with each ttyclose().
	 * We should adjust the slush allocation.  This can't be done in
	 * the i/o routines because they are sometimes called from
	 * interrupt handlers when it may be unsafe to call malloc().
	 */
	cblock_alloc_cblocks(cslushcount = INITIAL_CBLOCKS);
}

/*
 * Remove a cblock from the cfreelist queue and return a pointer
 * to it.
 */
static inline struct cblock *
cblock_alloc()
{
	struct cblock *cblockp;

	cblockp = cfreelist;
	if (cblockp == NULL)
		panic("clist reservation botch");
	cfreelist = cblockp->c_next;
	cblockp->c_next = NULL;
	cfreecount -= CBSIZE;
	return (cblockp);
}

/*
 * Add a cblock to the cfreelist queue.
 */
static inline void
cblock_free(cblockp)
	struct cblock *cblockp;
{
	if (isset(cblockp->c_quote, CBQSIZE * NBBY - 1))
		bzero(cblockp->c_quote, sizeof cblockp->c_quote);
	cblockp->c_next = cfreelist;
	cfreelist = cblockp;
	cfreecount += CBSIZE;
}

/*
 * Allocate some cblocks for the cfreelist queue.
 */
static void
cblock_alloc_cblocks(number)
	int number;
{
	int i;
	struct cblock *cbp;

	for (i = 0; i < number; ++i) {
		cbp = malloc(sizeof *cbp, M_TTYS, M_WAITOK);
		/*
		 * Freed cblocks have zero quotes and garbage elsewhere.
		 * Set the may-have-quote bit to force zeroing the quotes.
		 */
		setbit(cbp->c_quote, CBQSIZE * NBBY - 1);
		cblock_free(cbp);
	}
	ctotcount += number;
}

/*
 * Set the cblock allocation policy for a a clist.
 * Must be called in process context at spltty().
 */
void
clist_alloc_cblocks(clistp, ccmax, ccreserved)
	struct clist *clistp;
	int ccmax;
	int ccreserved;
{
	int dcbr;

	/*
	 * Allow for wasted space at the head.
	 */
	if (ccmax != 0)
		ccmax += CBSIZE - 1;
	if (ccreserved != 0)
		ccreserved += CBSIZE - 1;

	clistp->c_cbmax = roundup(ccmax, CBSIZE) / CBSIZE;
	dcbr = roundup(ccreserved, CBSIZE) / CBSIZE - clistp->c_cbreserved;
	if (dcbr >= 0)
		cblock_alloc_cblocks(dcbr);
	else {
		if (clistp->c_cbreserved + dcbr < clistp->c_cbcount)
			dcbr = clistp->c_cbcount - clistp->c_cbreserved;
		cblock_free_cblocks(-dcbr);
	}
	clistp->c_cbreserved += dcbr;
}

/*
 * Free some cblocks from the cfreelist queue back to the
 * system malloc pool.
 */
static void
cblock_free_cblocks(number)
	int number;
{
	int i;

	for (i = 0; i < number; ++i)
		free(cblock_alloc(), M_TTYS);
	ctotcount -= number;
}

/*
 * Free the cblocks reserved for a clist.
 * Must be called at spltty().
 */
void
clist_free_cblocks(clistp)
	struct clist *clistp;
{
	if (clistp->c_cbcount != 0)
		panic("freeing active clist cblocks");
	cblock_free_cblocks(clistp->c_cbreserved);
	clistp->c_cbmax = 0;
	clistp->c_cbreserved = 0;
}

/*
 * Get a character from the head of a clist.
 */
int
getc(clistp)
	struct clist *clistp;
{
	int chr = -1;
	int s;
	struct cblock *cblockp;

	s = spltty();

	/* If there are characters in the list, get one */
	if (clistp->c_cc) {
		cblockp = (struct cblock *)((long)clistp->c_cf & ~CROUND);
		chr = (u_char)*clistp->c_cf;

		/*
		 * If this char is quoted, set the flag.
		 */
		if (isset(cblockp->c_quote, clistp->c_cf - (char *)cblockp->c_info))
			chr |= TTY_QUOTE;

		/*
		 * Advance to next character.
		 */
		clistp->c_cf++;
		clistp->c_cc--;
		/*
		 * If we have advanced the 'first' character pointer
		 * past the end of this cblock, advance to the next one.
		 * If there are no more characters, set the first and
		 * last pointers to NULL. In either case, free the
		 * current cblock.
		 */
		if ((clistp->c_cf >= (char *)(cblockp+1)) || (clistp->c_cc == 0)) {
			if (clistp->c_cc > 0) {
				clistp->c_cf = cblockp->c_next->c_info;
			} else {
				clistp->c_cf = clistp->c_cl = NULL;
			}
			cblock_free(cblockp);
			if (--clistp->c_cbcount >= clistp->c_cbreserved)
				++cslushcount;
		}
	}

	splx(s);
	return (chr);
}

/*
 * Copy 'amount' of chars, beginning at head of clist 'clistp' to
 * destination linear buffer 'dest'. Return number of characters
 * actually copied.
 */
int
q_to_b(clistp, dest, amount)
	struct clist *clistp;
	char *dest;
	int amount;
{
	struct cblock *cblockp;
	struct cblock *cblockn;
	char *dest_orig = dest;
	int numc;
	int s;

	s = spltty();

	while (clistp && amount && (clistp->c_cc > 0)) {
		cblockp = (struct cblock *)((long)clistp->c_cf & ~CROUND);
		cblockn = cblockp + 1; /* pointer arithmetic! */
		numc = min(amount, (char *)cblockn - clistp->c_cf);
		numc = min(numc, clistp->c_cc);
		bcopy(clistp->c_cf, dest, numc);
		amount -= numc;
		clistp->c_cf += numc;
		clistp->c_cc -= numc;
		dest += numc;
		/*
		 * If this cblock has been emptied, advance to the next
		 * one. If there are no more characters, set the first
		 * and last pointer to NULL. In either case, free the
		 * current cblock.
		 */
		if ((clistp->c_cf >= (char *)cblockn) || (clistp->c_cc == 0)) {
			if (clistp->c_cc > 0) {
				clistp->c_cf = cblockp->c_next->c_info;
			} else {
				clistp->c_cf = clistp->c_cl = NULL;
			}
			cblock_free(cblockp);
			if (--clistp->c_cbcount >= clistp->c_cbreserved)
				++cslushcount;
		}
	}

	splx(s);
	return (dest - dest_orig);
}

/*
 * Flush 'amount' of chars, beginning at head of clist 'clistp'.
 */
void
ndflush(clistp, amount)
	struct clist *clistp;
	int amount;
{
	struct cblock *cblockp;
	struct cblock *cblockn;
	int numc;
	int s;

	s = spltty();

	while (amount && (clistp->c_cc > 0)) {
		cblockp = (struct cblock *)((long)clistp->c_cf & ~CROUND);
		cblockn = cblockp + 1; /* pointer arithmetic! */
		numc = min(amount, (char *)cblockn - clistp->c_cf);
		numc = min(numc, clistp->c_cc);
		amount -= numc;
		clistp->c_cf += numc;
		clistp->c_cc -= numc;
		/*
		 * If this cblock has been emptied, advance to the next
		 * one. If there are no more characters, set the first
		 * and last pointer to NULL. In either case, free the
		 * current cblock.
		 */
		if ((clistp->c_cf >= (char *)cblockn) || (clistp->c_cc == 0)) {
			if (clistp->c_cc > 0) {
				clistp->c_cf = cblockp->c_next->c_info;
			} else {
				clistp->c_cf = clistp->c_cl = NULL;
			}
			cblock_free(cblockp);
			if (--clistp->c_cbcount >= clistp->c_cbreserved)
				++cslushcount;
		}
	}

	splx(s);