NetBSD-5.0.2/usr.bin/telnet/ring.c
/* $NetBSD: ring.c,v 1.13 2003/08/07 11:16:10 agc Exp $ */
/*
* Copyright (c) 1988, 1993
* The Regents of the University of California. 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.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*/
#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)ring.c 8.2 (Berkeley) 5/30/95";
#else
__RCSID("$NetBSD: ring.c,v 1.13 2003/08/07 11:16:10 agc Exp $");
#endif
#endif /* not lint */
/*
* This defines a structure for a ring buffer.
*
* The circular buffer has two parts:
*(((
* full: [consume, supply)
* empty: [supply, consume)
*]]]
*
*/
#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include "ring.h"
#include "general.h"
/* Internal macros */
#if !defined(MIN)
#define MIN(a,b) (((a)<(b))? (a):(b))
#endif /* !defined(MIN) */
#define ring_subtract(d,a,b) (((a)-(b) >= 0)? \
(a)-(b): (((a)-(b))+(d)->size))
#define ring_increment(d,a,c) (((a)+(c) < (d)->top)? \
(a)+(c) : (((a)+(c))-(d)->size))
#define ring_decrement(d,a,c) (((a)-(c) >= (d)->bottom)? \
(a)-(c) : (((a)-(c))-(d)->size))
/*
* The following is a clock, used to determine full, empty, etc.
*
* There is some trickiness here. Since the ring buffers are initialized
* to ZERO on allocation, we need to make sure, when interpreting the
* clock, that when the times are EQUAL, then the buffer is FULL.
*/
static u_long ring_clock = 0;
#define ring_empty(d) (((d)->consume == (d)->supply) && \
((d)->consumetime >= (d)->supplytime))
#define ring_full(d) (((d)->supply == (d)->consume) && \
((d)->supplytime > (d)->consumetime))
/* Buffer state transition routines */
int
ring_init(Ring *ring, unsigned char *buffer, int count)
{
memset((char *)ring, 0, sizeof *ring);
ring->size = count;
ring->supply = ring->consume = ring->bottom = buffer;
ring->top = ring->bottom+ring->size;
#ifdef ENCRYPTION
ring->clearto = 0;
#endif /* ENCRYPTION */
return 1;
}
/* Mark routines */
/*
* Mark the most recently supplied byte.
*/
void
ring_mark(Ring *ring)
{
ring->mark = ring_decrement(ring, ring->supply, 1);
}
/*
* Is the ring pointing to the mark?
*/
int
ring_at_mark(Ring *ring)
{
if (ring->mark == ring->consume) {
return 1;
} else {
return 0;
}
}
/*
* Clear any mark set on the ring.
*/
void
ring_clear_mark(Ring *ring)
{
ring->mark = 0;
}
/*
* Add characters from current segment to ring buffer.
*/
void
ring_supplied(Ring *ring, int count)
{
ring->supply = ring_increment(ring, ring->supply, count);
ring->supplytime = ++ring_clock;
}
/*
* We have just consumed "c" bytes.
*/
void
ring_consumed(Ring *ring, int count)
{
if (count == 0) /* don't update anything */
return;
if (ring->mark &&
(ring_subtract(ring, ring->mark, ring->consume) < count)) {
ring->mark = 0;
}
#ifdef ENCRYPTION
if (ring->consume < ring->clearto &&
ring->clearto <= ring->consume + count)
ring->clearto = 0;
else if (ring->consume + count > ring->top &&
ring->bottom <= ring->clearto &&
ring->bottom + ((ring->consume + count) - ring->top))
ring->clearto = 0;
#endif /* ENCRYPTION */
ring->consume = ring_increment(ring, ring->consume, count);
ring->consumetime = ++ring_clock;
/*
* Try to encourage "ring_empty_consecutive()" to be large.
*/
if (ring_empty(ring)) {
ring->consume = ring->supply = ring->bottom;
}
}
/* Buffer state query routines */
/* Number of bytes that may be supplied */
int
ring_empty_count(Ring *ring)
{
if (ring_empty(ring)) { /* if empty */
return ring->size;
} else {
return ring_subtract(ring, ring->consume, ring->supply);
}
}
/* number of CONSECUTIVE bytes that may be supplied */
int
ring_empty_consecutive(Ring *ring)
{
if ((ring->consume < ring->supply) || ring_empty(ring)) {
/*
* if consume is "below" supply, or empty, then
* return distance to the top
*/
return ring_subtract(ring, ring->top, ring->supply);
} else {
/*
* else, return what we may.
*/
return ring_subtract(ring, ring->consume, ring->supply);
}
}
/* Return the number of bytes that are available for consuming
* (but don't give more than enough to get to cross over set mark)
*/
int
ring_full_count(Ring *ring)
{
if ((ring->mark == 0) || (ring->mark == ring->consume)) {
if (ring_full(ring)) {
return ring->size; /* nothing consumed, but full */
} else {
return ring_subtract(ring, ring->supply, ring->consume);
}
} else {
return ring_subtract(ring, ring->mark, ring->consume);
}
}
/*
* Return the number of CONSECUTIVE bytes available for consuming.
* However, don't return more than enough to cross over set mark.
*/
int
ring_full_consecutive(Ring *ring)
{
if ((ring->mark == 0) || (ring->mark == ring->consume)) {
if ((ring->supply < ring->consume) || ring_full(ring)) {
return ring_subtract(ring, ring->top, ring->consume);
} else {
return ring_subtract(ring, ring->supply, ring->consume);
}
} else {
if (ring->mark < ring->consume) {
return ring_subtract(ring, ring->top, ring->consume);
} else { /* Else, distance to mark */
return ring_subtract(ring, ring->mark, ring->consume);
}
}
}
/*
* Move data into the "supply" portion of of the ring buffer.
*/
void
ring_supply_data(Ring *ring, unsigned char *buffer, int count)
{
int i;
while (count) {
i = MIN(count, ring_empty_consecutive(ring));
memmove(ring->supply, buffer, i);
ring_supplied(ring, i);
count -= i;
buffer += i;
}
}
#ifdef notdef
/*
* Move data from the "consume" portion of the ring buffer
*/
void
ring_consume_data(Ring *ring, unsigned char *buffer, int count)
{
int i;
while (count) {
i = MIN(count, ring_full_consecutive(ring));
memmove(buffer, ring->consume, i);
ring_consumed(ring, i);
count -= i;
buffer += i;
}
}
#endif
#ifdef ENCRYPTION
void
ring_encrypt(Ring *ring, void (*encryptor)(unsigned char *, int))
{
unsigned char *s, *c;
if (ring_empty(ring) || ring->clearto == ring->supply)
return;
if (!(c = ring->clearto))
c = ring->consume;
s = ring->supply;
if (s <= c) {
(*encryptor)(c, ring->top - c);
(*encryptor)(ring->bottom, s - ring->bottom);
} else
(*encryptor)(c, s - c);
ring->clearto = ring->supply;
}
void
ring_clearto(Ring *ring)
{
if (!ring_empty(ring))
ring->clearto = ring->supply;
else
ring->clearto = 0;
}
#endif /* ENCRYPTION */