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#include "core.h"
#include <string.h>
#define SEQ_HALF ((ecp_seq_t)1 << (sizeof(ecp_seq_t)*8-1))
#define ACK_FULL (~(ecp_ack_t)0)
#define ACK_SIZE (sizeof(ecp_ack_t)*8)
#define ACK_MASK_FIRST ((ecp_ack_t)1 << (ACK_SIZE - 1))
#define SEQ_LT(a,b) ((ecp_seq_t)((ecp_seq_t)(a) - (ecp_seq_t)(b)) > SEQ_HALF)
#define SEQ_LTE(a,b) ((ecp_seq_t)((ecp_seq_t)(b) - (ecp_seq_t)(a)) < SEQ_HALF)
#define IDX_MASK(a) (a & (ECP_MAX_RBUF_MSGR-1))
/* If ECP_MAX_RBUF_MSGR not pow of 2:
#define IDX_MASK(a) (a % ECP_MAX_RBUF_MSGR)
*/
static int msg_idx(ECPRBuffer *rbuf, ecp_seq_t seq) {
ecp_seq_t seq_offset = seq - rbuf->seq_start;
if (seq_offset < ECP_MAX_RBUF_MSGR) return IDX_MASK(rbuf->msg_start + seq_offset);
return ECP_ERR_RBUF_IDX;
}
static int msg_store(ECPRBuffer *rbuf, ecp_seq_t seq, unsigned char *msg, size_t msg_size, unsigned char delivered) {
int idx;
ecp_seq_t seq_offset = seq - rbuf->seq_start;
if (seq_offset >= ECP_MAX_RBUF_MSGR) return ECP_ERR_RBUF_IDX;
if (SEQ_LT(rbuf->seq_max, seq)) rbuf->seq_max = seq;
if (delivered) return ECP_OK;
idx = msg_idx(rbuf, seq);
if (idx < 0) return idx;
if (rbuf->msg[idx].present) return ECP_ERR_RBUF_DUP;
rbuf->msg[idx].present = 1;
return ECP_OK;
}
static int msg_flush(ECPConnection *conn, ECPRBuffer *rbuf) {
int idx = rbuf->msg_start;
ecp_seq_t msg_cnt = rbuf->seq_max - rbuf->seq_start + 1;
ecp_seq_t i = 0;
for (i=0; i<msg_cnt; i++) {
if (rbuf->reliable && !rbuf->msg[idx].present) break;
if (rbuf->deliver_delay && msg_cnt - i < rbuf->deliver_delay) break;
if (rbuf->msg[idx].present) {
rbuf->msg[idx].present = 0;
// deliver idx
}
idx = IDX_MASK(idx + 1);
}
rbuf->msg_start = idx;
rbuf->seq_start += i;
return ECP_OK;
}
static int ack_shift(ECPRBuffer *rbuf) {
int do_ack = 0;
int idx;
int i;
if (rbuf->reliable && ((rbuf->ack_map & ACK_MASK_FIRST) == 0)) return 0;
idx = msg_idx(rbuf, rbuf->seq_ack);
if (idx < 0) return idx;
while (SEQ_LT(rbuf->seq_ack, rbuf->seq_max)) {
idx = IDX_MASK(idx + 1);
rbuf->seq_ack++;
if (rbuf->msg[idx].present && (rbuf->ack_map == ACK_FULL)) continue;
rbuf->ack_map = rbuf->ack_map << 1;
rbuf->ack_map |= rbuf->msg[idx].present;
if (!do_ack && !rbuf->msg[idx].present && SEQ_LTE(rbuf->seq_ack, rbuf->seq_max - 2 * rbuf->hole_max)) {
do_ack = 1;
}
if ((rbuf->ack_map & ACK_MASK_FIRST) == 0) break;
}
if (!do_ack && (rbuf->seq_ack == rbuf->seq_max) && ((rbuf->ack_map & rbuf->hole_mask_full) != rbuf->hole_mask_full)) {
ecp_ack_t hole_mask = rbuf->ack_map;
for (i=0; i<rbuf->hole_max-1; i++) {
hole_mask = hole_mask >> 1;
if ((hole_mask & rbuf->hole_mask_empty) == 0) {
do_ack = 1;
break;
}
}
}
return do_ack;
}
int ecp_rbuf_recv_init(ECPRBuffer *rbuf, ecp_seq_t seq, unsigned char hole_max) {
memset(rbuf, 0, sizeof(ECPRBuffer));
rbuf->hole_max = hole_max;
rbuf->hole_mask_full = ~(~((ecp_ack_t)0) << (hole_max * 2));
rbuf->hole_mask_empty = ~(~((ecp_ack_t)0) << (hole_max + 1));
rbuf->seq_ack = seq;
rbuf->seq_max = seq;
rbuf->seq_start = seq + 1;
rbuf->ack_map = ACK_FULL;
return ECP_OK;
}
ssize_t ecp_rbuf_recv_store(ECPConnection *conn, ecp_seq_t seq, unsigned char *msg, size_t msg_size) {
int rv;
int do_ack = 0;
ECPRBuffer *rbuf = conn->rbuf.recv;
if (rbuf == NULL) return ECP_ERR;
if (SEQ_LTE(seq, rbuf->seq_ack)) {
if ((ecp_seq_t)(rbuf->seq_ack - seq) < ACK_SIZE) {
rv = msg_store(rbuf, seq, msg, msg_size, 0);
if (rv) return rv;
rbuf->ack_map |= (1 << (ecp_seq_t)(rbuf->seq_ack - seq));
do_ack = ack_shift(rbuf);
} else {
return ECP_ERR_RBUF_IDX;
}
} else {
if ((rbuf->ack_map == ACK_FULL) && (seq == (ecp_seq_t)(rbuf->seq_ack + 1))) {
rv = msg_store(rbuf, seq, msg, msg_size, !rbuf->deliver_delay);
if (rv) return rv;
if (!rbuf->deliver_delay) {
rbuf->seq_start++;
// deliver
}
rbuf->seq_ack++;
} else {
rv = msg_store(rbuf, seq, msg, msg_size, 0);
if (rv) return rv;
do_ack = ack_shift(rbuf);
}
}
// XXX
// update do_ack for pps
// should send acks more aggresively when ack_map is not full (freq > RTT)
// now send acks as per do_ack
return msg_size;
}
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