telnet/telnet/ring.c

32 static const char sccsid[] = "@(#)ring.c	8.2 (Berkeley) 5/30/95";
36 __FBSDID("$FreeBSD: stable/11/contrib/telnet/telnet/ring.c 351432 2019-08-23 17:40:47Z emaste $");
39  * This defines a structure for a ring buffer.
63 #include	"ring.h"
85  * There is some trickiness here.  Since the ring buffers are initialized
100 ring_init(Ring *ring, unsigned char *buffer, int count)
102     memset((char *)ring, 0, sizeof *ring);
104     ring->size = count;
106     ring->supply = ring->consume = ring->bottom = buffer;
108     ring->top = ring->bottom+ring->size;
111     ring->clearto = 0;
124 ring_mark(Ring *ring)
126     ring->mark = ring_decrement(ring, ring->supply, 1);
130  * Is the ring pointing to the mark?
134 ring_at_mark(Ring *ring)
136     if (ring->mark == ring->consume) {
144  * Clear any mark set on the ring.
148 ring_clear_mark(Ring *ring)
150     ring->mark = 0;
154  * Add characters from current segment to ring buffer.
157 ring_supplied(Ring *ring, int count)
159     ring->supply = ring_increment(ring, ring->supply, count);
160     ring->supplytime = ++ring_clock;
167 ring_consumed(Ring *ring, int count)
172     if (ring->mark &&
173 		(ring_subtract(ring, ring->mark, ring->consume) < count)) {
174 	ring->mark = 0;
177     if (ring->consume < ring->clearto &&
178 		ring->clearto <= ring->consume + count)
179 	ring->clearto = 0;
180     else if (ring->consume + count > ring->top &&
181 		ring->bottom <= ring->clearto &&
182 		ring->bottom + ((ring->consume + count) - ring->top))
183 	ring->clearto = 0;
185     ring->consume = ring_increment(ring, ring->consume, count);
186     ring->consumetime = ++ring_clock;
190     if (ring_empty(ring)) {
191 	ring->consume = ring->supply = ring->bottom;
202 ring_empty_count(Ring *ring)
204     if (ring_empty(ring)) {	/* if empty */
205 	    return ring->size;
207 	return ring_subtract(ring, ring->consume, ring->supply);
213 ring_empty_consecutive(Ring *ring)
215     if ((ring->consume < ring->supply) || ring_empty(ring)) {
220 	return ring_subtract(ring, ring->top, ring->supply);
225 	return ring_subtract(ring, ring->consume, ring->supply);
234 ring_full_count(Ring *ring)
236     if ((ring->mark == 0) || (ring->mark == ring->consume)) {
237 	if (ring_full(ring)) {
238 	    return ring->size;	/* nothing consumed, but full */
240 	    return ring_subtract(ring, ring->supply, ring->consume);
243 	return ring_subtract(ring, ring->mark, ring->consume);
252 ring_full_consecutive(Ring *ring)
254     if ((ring->mark == 0) || (ring->mark == ring->consume)) {
255 	if ((ring->supply < ring->consume) || ring_full(ring)) {
256 	    return ring_subtract(ring, ring->top, ring->consume);
258 	    return ring_subtract(ring, ring->supply, ring->consume);
261 	if (ring->mark < ring->consume) {
262 	    return ring_subtract(ring, ring->top, ring->consume);
264 	    return ring_subtract(ring, ring->mark, ring->consume);
270  * Move data into the "supply" portion of of the ring buffer.
273 ring_supply_data(Ring *ring, unsigned char *buffer, int count)
278 	i = MIN(count, ring_empty_consecutive(ring));
279 	memcpy(ring->supply, buffer, i);
280 	ring_supplied(ring, i);
288 ring_encrypt(Ring *ring, void (*encryptor)(unsigned char *, int))
292     if (ring_empty(ring) || ring->clearto == ring->supply)
295     if (!(c = ring->clearto))
296 	c = ring->consume;
298     s = ring->supply;
301 	(*encryptor)(c, ring->top - c);
302 	(*encryptor)(ring->bottom, s - ring->bottom);
306     ring->clearto = ring->supply;
310 ring_clearto(ring)
311     Ring *ring;
313     if (!ring_empty(ring))
314 	ring->clearto = ring->supply;
316 	ring->clearto = 0;