int spsc_trypop_slot_pass() {
cqueue_spsc *q;
int i;
char data;
char *p;
q = cqueue_spsc_new(26, sizeof(char));
assert(q);
// insert dummy data for testing
for(i=0, data='A'; i < 26; i++, data++) {
p = cqueue_spsc_trypush_slot(q);
assert(p);
*p = data;
cqueue_spsc_push_slot_finish(q);
}
// pop some data so we're not at the start
for(i=0; i < 13; i++) {
p = cqueue_spsc_trypop_slot(q);
assert(p);
cqueue_spsc_pop_slot_finish(q);
}
// check index, used flag, and data
assert(q->pop_idx == 13);
void *offset = (char *)(q->array + 12*q->elem_size);
size_t used = *(size_t *)offset;
assert(used == 0);
assert(*p == 'M');
return 1;
}
// initialize each slot in the xmit queue with ethernet header and
// arp data that is consistent between requests and replies
int xmit_queue_init(cqueue_spsc *q, struct in_addr *my_ip,
struct ether_addr *my_mac) {
struct xmit_queue_slot *s;
struct arp_pkt *arp;
size_t ether_arp_len, i, start_idx;
ether_arp_len = sizeof(struct ether_header) + sizeof(struct arp_pkt);
if (ether_arp_len < ETHER_MIN_LEN - ETHER_CRC_LEN)
ether_arp_len = ETHER_MIN_LEN - ETHER_CRC_LEN;
start_idx = q->push_idx;
for (i=0; i < q->capacity; i++) {
s = cqueue_spsc_push_slot(q);
if (!s)
return 0;
s->len = ether_arp_len;
/* ethernet header */
memcpy(s->ether_h.ether_shost, my_mac, sizeof(struct ether_addr));
s->ether_h.ether_type = ARP_ETHERTYPE;
// ether_dhost changes in a request or reply
/* arp */
arp = (struct arp_pkt *)s->data;
arp->arp_h.ar_hrd = ARP_HAF_ETHER;
arp->arp_h.ar_pro = IP4_ETHERTYPE;
arp->arp_h.ar_hln = ETHER_ADDR_LEN;
arp->arp_h.ar_pln = sizeof(struct in_addr);
// ar_op changes for request/reply
memcpy(&arp->sha, my_mac, sizeof(struct ether_addr));
arp->spa.s_addr = my_ip->s_addr;
// tha and tpa change in a request/reply
cqueue_spsc_push_slot_finish(q);
// reset the slot used flag without touching the data
s = cqueue_spsc_pop_slot(q);
if (!s)
return 0;
cqueue_spsc_pop_slot_finish(q);
}
// detect if something else pushed while we were initializing
if (q->push_idx != start_idx)
return 0;
return 1;
}
/*!
Warning: this function relies on internal knowledge of cqueue_spsc
to optimize num_actions
*/
tqueue *tqueue_new(size_t num_transactions, size_t num_actions) {
tqueue *q;
transaction *t;
size_t transaction_size;
if (!num_transactions)
return NULL;
if (!num_actions)
return NULL;
// check overflow
if (num_actions > (SIZE_MAX - sizeof(transaction)) / sizeof (void *))
return NULL;
transaction_size = sizeof(transaction) + num_actions * sizeof(void *);
q = malloc(sizeof(tqueue));
if (!q)
return NULL;
q->transactions = cqueue_spsc_new(num_transactions, transaction_size);
if (!q->transactions) {
free(q);
return NULL;
}
q->num_transactions = num_transactions;
q->num_actions = (q->transactions->elem_size - sizeof(_Atomic size_t)
- sizeof(transaction)) / sizeof(void *);
// initialize the transactions
while ((t = cqueue_spsc_trypush_slot(q->transactions)) != NULL) {
t->write_idx = 0;
t->read_idx = 0;
cqueue_spsc_push_slot_finish(q->transactions);
}
while ((t = cqueue_spsc_trypop_slot(q->transactions)) != NULL) {
cqueue_spsc_pop_slot_finish(q->transactions);
}
return q;
}
int tqueue_remove(tqueue *q, transaction **tp, void **p) {
assert(q);
transaction *t = *tp;
if (!t) {
t = cqueue_spsc_trypop_slot(q->transactions);
if (!t) // transaction queue empty
return TQUEUE_EMPTY;
}
*p = t->actions[t->read_idx];
t->read_idx++;
if (t->read_idx == t->write_idx) { // we've read everything
t->write_idx = 0;
t->read_idx = 0;
t = NULL;
cqueue_spsc_pop_slot_finish(q->transactions);
return TQUEUE_TRANSACTION_EMPTY;
}
return TQUEUE_SUCCESS;
}
