-
-
-
-
-static int nm_handle_can_frame(struct NM_Main *nm, struct can_frame *frame)
+static int nm_is_rx_frame_valid(struct NM_Main *nm, struct can_frame *frame)
{
- NM_ID id;
- NM_ID next;
- NM_State state;
- int its_my_turn = 0;
-
if (frame->can_dlc < 2) {
printf("Skipping short frame from CAN ID %03x\n", frame->can_id);
return 0;
}
-
if ((frame->can_id & ~(nm->max_nodes - 1)) != nm->can_base) {
printf("Skipping non-NM from CAN ID %03x\n", frame->can_id);
return 0;
}
+ return 1;
+}
+
+
+
+
+static void nm_update_my_next_id(struct NM_Main *nm) {
+ unsigned id = nm->my_id;
+
+ do {
+ NM_State state;
+
+ id++;
+ if (id >= nm->max_nodes) {
+ id = 0;
+ }
+
+ state = nm->nodes[id].state & NM_MAIN_MASK;
+
+ if (state == NM_MAIN_ON || state == NM_MAIN_LOGIN) {
+ /* TODO: Check for limp home nodes? */
+ nm->nodes[nm->my_id].next = id;
+ break;
+ }
+ } while (id != nm->my_id);
+}
+
+
+
+static void nm_handle_can_frame(struct NM_Main *nm, struct can_frame *frame)
+{
+ NM_ID sender, next;
+ NM_State state;
+
+ /* Is this a valid frame within our logical network? */
+ if (!nm_is_rx_frame_valid(nm, frame)) {
+ return;
+ }
+
printf("Received NM frame from CAN ID %03x\n", frame->can_id);
- id = frame->can_id & (nm->max_nodes - 1);
+
+ /* Parse sender, its perceived successor, and its state */
+ sender = frame->can_id & (nm->max_nodes - 1);
next = frame->data[0];
state = frame->data[1];
- nm->nodes[id].next = (state & NM_MAIN_MASK) == NM_MAIN_ON
- ? next
- : 0xff;
- nm->nodes[id].state = state;
+ /* TODO: Validate state, it needs to be within the enum */
+
+ /* Skip our own frames */
+ if (sender == nm->my_id) {
+ return;
+ }
+
+ nm->nodes[sender].next = next;
+ nm->nodes[sender].state = state;
switch (state & NM_MAIN_MASK) {
case NM_MAIN_ON:
- if (next == nm->my_id) {
- its_my_turn = 1;
+ if (next == nm->nodes[nm->my_id].next
+ && nm->nodes[nm->my_id].next != nm->my_id) {
+ /* sender doesn't know we exist */
+
+ nm->nodes[nm->my_id].state = NM_MAIN_LOGIN;
+
+ nm->tv.tv_sec = 0;
+ nm->tv.tv_usec = 0;
+ /* IMPORTANT: The caller needs to check for
+ * timeouts first, so no other NM frames are
+ * received until our correcting login has
+ * been sent.
+ */
+ } else if (next == nm->nodes[nm->my_id].next) {
+ /* where nm->nodes[nm->my_id].next == nm->my_id */
+
+ /* TODO: Is this a case we need to handle? */
+
+ /* It can happen when:
+ * - our sent frames don't go anywhere
+ * - we just logged in and immediately
+ * afterwards another ECU sent a regular
+ * NM frame without knowing that we exist.
+ */
+ } else if (next == nm->my_id) {
+ /* It's our turn.
+ * Reset the timeout so anyone we missed
+ * can send its login frame to correct us.
+ */
+ nm->tv.tv_sec = 0;
+ nm->tv.tv_usec = NM_USECS_MY_TURN;
+ } else {
+ /* We just got some random ON message.
+ * Reset the timer looking out for broken
+ * connectivity.
+ */
+ nm->tv.tv_sec = 0;
+ nm->tv.tv_usec = NM_USECS_OTHER_TURN;
}
break;
case NM_MAIN_LOGIN:
- if (id == nm->my_id) {
- break;
- }
+ /* Note: sender != nm->my_id */
+
printf("Handling LOGIN\n");
- printf("Testing %x < %x\n", id, nm->nodes[nm->my_id].next);
- if (id < nm->nodes[nm->my_id].next) {
- nm->nodes[nm->my_id].next = id;
- }
+
+ nm_update_my_next_id(nm);
+
+ /* We're not alone anymore, so let's change state. */
+ nm->nodes[nm->my_id].state = NM_MAIN_ON;
+
+ /* We don't reset the timeout when somebody logs in.
+ * Instead, we'll simply include them in the next
+ * round. */
+
+ /* Actually, when a login is done as a correction,
+ * we do reset the timeout.
+ *
+ * TODO.
+ */
break;
}
nm_dump_all(nm);
-
- return its_my_turn;
}
-static NM_ID nm_my_next_id(struct NM_Main *nm) {
- unsigned id;
- if (nm->max_nodes < 2
- || (nm->nodes[nm->my_id].state & NM_MAIN_MASK) != NM_MAIN_ON) {
- assert(0);
- }
- id = nm->my_id;
- do {
- struct NM_Node *node;
+static void nm_buildframe(struct NM_Main *nm, struct can_frame *frame)
+{
+ frame->can_id = nm->can_base + nm->my_id;
+ frame->can_dlc = 2;
+ frame->data[0] = nm->nodes[nm->my_id].next;
+ frame->data[1] = nm->nodes[nm->my_id].state;
+}
- id++;
- if (id >= nm->max_nodes) {
- id = 0;
- }
- node = &nm->nodes[id];
- if ((node->state & NM_MAIN_MASK) == NM_MAIN_ON) {
- return id;
- }
- } while (id != nm->my_id);
- /* This is never reached */
- assert(0);
- return -1;
+
+static void nm_timeout_callback(struct NM_Main *nm, struct can_frame *frame)
+{
+ nm->tv.tv_sec = 0;
+ nm->tv.tv_usec = NM_USECS_OTHER_TURN;
+
+ nm_buildframe(nm, frame);
}
-static void nm_timeout_callback(struct NM_Main *nm, struct can_frame *frame) {
- nm->nodes[nm->my_id].next = nm_my_next_id(nm);
+static void nm_start(struct NM_Main *nm, struct can_frame *frame)
+{
+ nm->tv.tv_sec = 0;
+ nm->tv.tv_usec = 50000;
- frame->can_id = nm->can_base + nm->my_id;
- frame->can_dlc = 2;
- frame->data[0] = nm->nodes[nm->my_id].next;
- frame->data[1] = NM_MAIN_ON;
+
+
+ nm->nodes[nm->my_id].next = nm->my_id;
+ nm->nodes[nm->my_id].state = NM_MAIN_LOGIN;
+
+ nm_buildframe(nm, frame);
}
int main(int argc, char **argv)
{
struct NM_Main *nm;
- struct timeval tv, *next_tv = NULL;
fd_set rdfs;
int s;
s = net_init(argv[1]);
+ /* Stir up the hornet's nest */
+ if (1) {
+ struct can_frame frame;
+
+ nm_start(nm, &frame);
+ can_tx(s, &frame);
+ }
+
while (1) {
int retval;
FD_ZERO(&rdfs);
FD_SET(s, &rdfs);
- retval = select(s+1, &rdfs, NULL, NULL, next_tv);
+ retval = select(s+1, &rdfs, NULL, NULL, &nm->tv);
/* We currently rely on Linux timeout behavior here,
* i.e. the timeout now reflects the remaining time */
if (retval < 0) {
perror("select");
return 1;
} else if (!retval) {
- /* Timeout */
+ /* Timeout, we NEED to check this first */
struct can_frame frame;
nm_timeout_callback(nm, &frame);
can_tx(s, &frame);
-
- next_tv = NULL;
} else if (FD_ISSET(s, &rdfs)) {
struct can_frame frame;
ssize_t ret;
return 1;
}
- if (nm_handle_can_frame(nm, &frame)) {
- tv.tv_sec = 0;
- tv.tv_usec = 400000;
- next_tv = &tv;
- }
+ nm_handle_can_frame(nm, &frame);
continue;
}
}
projects / revag-nm.git / commitdiff