telnet/telnet/ring.c

39  * This defines a structure for a ring buffer.
64  * There is some trickiness here.  Since the ring buffers are initialized
83 ring_init(Ring *ring, unsigned char *buffer, int count)
85     memset(ring, 0, sizeof *ring);
87     ring->size = count;
89     ring->supply = ring->consume = ring->bottom = buffer;
91     ring->top = ring->bottom+ring->size;
94     ring->clearto = 0;
107 ring_mark(Ring *ring)
109     ring->mark = ring_decrement(ring, ring->supply, 1);
113  * Is the ring pointing to the mark?
117 ring_at_mark(Ring *ring)
119     if (ring->mark == ring->consume) {
127  * Clear any mark set on the ring.
131 ring_clear_mark(Ring *ring)
133     ring->mark = 0;
137  * Add characters from current segment to ring buffer.
140 ring_supplied(Ring *ring, int count)
142     ring->supply = ring_increment(ring, ring->supply, count);
143     ring->supplytime = ++ring_clock;
150 ring_consumed(Ring *ring, int count)
155     if (ring->mark &&
156 		(ring_subtract(ring, ring->mark, ring->consume) < count)) {
157 	ring->mark = 0;
160     if (ring->consume < ring->clearto &&
161 		ring->clearto <= ring->consume + count)
162 	ring->clearto = 0;
163     else if (ring->consume + count > ring->top &&
164 		ring->bottom <= ring->clearto &&
165 		ring->bottom + ((ring->consume + count) - ring->top))
166 	ring->clearto = 0;
168     ring->consume = ring_increment(ring, ring->consume, count);
169     ring->consumetime = ++ring_clock;
173     if (ring_empty(ring)) {
174 	ring->consume = ring->supply = ring->bottom;
185 ring_empty_count(Ring *ring)
187     if (ring_empty(ring)) {	/* if empty */
188 	    return ring->size;
190 	return ring_subtract(ring, ring->consume, ring->supply);
196 ring_empty_consecutive(Ring *ring)
198     if ((ring->consume < ring->supply) || ring_empty(ring)) {
203 	return ring_subtract(ring, ring->top, ring->supply);
208 	return ring_subtract(ring, ring->consume, ring->supply);
217 ring_full_count(Ring *ring)
219     if ((ring->mark == 0) || (ring->mark == ring->consume)) {
220 	if (ring_full(ring)) {
221 	    return ring->size;	/* nothing consumed, but full */
223 	    return ring_subtract(ring, ring->supply, ring->consume);
226 	return ring_subtract(ring, ring->mark, ring->consume);
235 ring_full_consecutive(Ring *ring)
237     if ((ring->mark == 0) || (ring->mark == ring->consume)) {
238 	if ((ring->supply < ring->consume) || ring_full(ring)) {
239 	    return ring_subtract(ring, ring->top, ring->consume);
241 	    return ring_subtract(ring, ring->supply, ring->consume);
244 	if (ring->mark < ring->consume) {
245 	    return ring_subtract(ring, ring->top, ring->consume);
247 	    return ring_subtract(ring, ring->mark, ring->consume);
253  * Move data into the "supply" portion of of the ring buffer.
256 ring_supply_data(Ring *ring, unsigned char *buffer, int count)
261 	i = min(count, ring_empty_consecutive(ring));
262 	memmove(ring->supply, buffer, i);
263 	ring_supplied(ring, i);
272  * Move data from the "consume" portion of the ring buffer
275 ring_consume_data(Ring *ring, unsigned char *buffer, int count)
280 	i = min(count, ring_full_consecutive(ring));
281 	memmove(buffer, ring->consume, i);
282 	ring_consumed(ring, i);
291 ring_encrypt(Ring *ring, void (*encryptor)(unsigned char *, int))
295     if (ring_empty(ring) || ring->clearto == ring->supply)
298     if (!(c = ring->clearto))
299 	c = ring->consume;
301     s = ring->supply;
304 	(*encryptor)(c, ring->top - c);
305 	(*encryptor)(ring->bottom, s - ring->bottom);
309     ring->clearto = ring->supply;
313 ring_clearto(Ring *ring)
315     if (!ring_empty(ring))
316 	ring->clearto = ring->supply;
318 	ring->clearto = 0;