#include "telnet_locl.h"
RCSID("$Id$");
#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))
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))
int
ring_init(Ring *ring, unsigned char *buffer, int count)
{
memset(ring, 0, sizeof *ring);
ring->size = count;
ring->supply = ring->consume = ring->bottom = buffer;
ring->top = ring->bottom+ring->size;
#if defined(ENCRYPTION)
ring->clearto = 0;
#endif
return 1;
}
void
ring_mark(Ring *ring)
{
ring->mark = ring_decrement(ring, ring->supply, 1);
}
int
ring_at_mark(Ring *ring)
{
if (ring->mark == ring->consume) {
return 1;
} else {
return 0;
}
}
void
ring_clear_mark(Ring *ring)
{
ring->mark = 0;
}
void
ring_supplied(Ring *ring, int count)
{
ring->supply = ring_increment(ring, ring->supply, count);
ring->supplytime = ++ring_clock;
}
void
ring_consumed(Ring *ring, int count)
{
if (count == 0)
return;
if (ring->mark &&
(ring_subtract(ring, ring->mark, ring->consume) < count)) {
ring->mark = 0;
}
#if defined(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
ring->consume = ring_increment(ring, ring->consume, count);
ring->consumetime = ++ring_clock;
if (ring_empty(ring)) {
ring->consume = ring->supply = ring->bottom;
}
}
int
ring_empty_count(Ring *ring)
{
if (ring_empty(ring)) {
return ring->size;
} else {
return ring_subtract(ring, ring->consume, ring->supply);
}
}
int
ring_empty_consecutive(Ring *ring)
{
if ((ring->consume < ring->supply) || ring_empty(ring)) {
return ring_subtract(ring, ring->top, ring->supply);
} else {
return ring_subtract(ring, ring->consume, ring->supply);
}
}
int
ring_full_count(Ring *ring)
{
if ((ring->mark == 0) || (ring->mark == ring->consume)) {
if (ring_full(ring)) {
return ring->size;
} else {
return ring_subtract(ring, ring->supply, ring->consume);
}
} else {
return ring_subtract(ring, ring->mark, ring->consume);
}
}
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 {
return ring_subtract(ring, ring->mark, ring->consume);
}
}
}
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
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
#if defined(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