static void init_route_structs (int bb_factor) {
/* Call this before you route any nets. It frees any old traceback and *
* sets the list of rr_nodes touched to empty. */
int i;
for (i=0;i<num_nets;i++)
free_traceback (i);
load_route_bb (bb_factor);
/* Check that things that should have been emptied after the last routing *
* really were. */
if (rr_modified_head != NULL) {
printf ("Error in init_route_structs. List of modified rr nodes is \n"
"not empty.\n");
exit (1);
}
if (heap_tail != 1) {
printf ("Error in init_route_structs. Heap is not empty.\n");
exit (1);
}
}
void restore_routing (struct s_trace **best_routing, t_ivec
**clb_opins_used_locally, t_ivec **saved_clb_opins_used_locally) {
/* Deallocates any current routing in trace_head, and replaces it with *
* the routing in best_routing. Best_routing is set to NULL to show that *
* it no longer points to a valid routing. NOTE: trace_tail is not *
* restored -- it is set to all NULLs since it is only used in *
* update_traceback. If you need trace_tail restored, modify this *
* routine. Also restores the locally used opin data. */
int inet, iblk, ipin, iclass, num_local_opins;
for (inet=0;inet<num_nets;inet++) {
/* Free any current routing. */
free_traceback (inet);
/* Set the current routing to the saved one. */
trace_head[inet] = best_routing[inet];
best_routing[inet] = NULL; /* No stored routing. */
}
/* Save which OPINs are locally used. */
for (iblk=0;iblk<num_blocks;iblk++) {
for (iclass=0;iclass<num_class;iclass++) {
num_local_opins = clb_opins_used_locally[iblk][iclass].nelem;
for (ipin=0;ipin<num_local_opins;ipin++) {
clb_opins_used_locally[iblk][iclass].list[ipin] =
saved_clb_opins_used_locally[iblk][iclass].list[ipin];
}
}
}
}
void
free_trace_structs(void)
{
/*the trace lists are only freed after use by the timing-driven placer */
/*Do not free them after use by the router, since stats, and draw */
/*routines use the trace values */
int i;
for(i = 0; i < num_nets; i++)
free_traceback(i);
free(trace_head);
free(trace_tail);
trace_head = NULL;
trace_tail = NULL;
}
static boolean breadth_first_route_net (int inet, float bend_cost) {
/* Uses a maze routing (Dijkstra's) algorithm to route a net. The net *
* begins at the net output, and expands outward until it hits a target *
* pin. The algorithm is then restarted with the entire first wire segment *
* included as part of the source this time. For an n-pin net, the maze *
* router is invoked n-1 times to complete all the connections. Inet is *
* the index of the net to be routed. Bends are penalized by bend_cost *
* (which is typically zero for detailed routing and nonzero only for global *
* routing), since global routes with lots of bends are tougher to detailed *
* route (using a detailed router like SEGA). *
* If this routine finds that a net *cannot* be connected (due to a complete *
* lack of potential paths, rather than congestion), it returns FALSE, as *
* routing is impossible on this architecture. Otherwise it returns TRUE. */
int i, inode, prev_node, remaining_connections_to_sink;
float pcost, new_pcost;
struct s_heap *current;
struct s_trace *tptr;
free_traceback (inet);
breadth_first_add_source_to_heap (inet);
mark_ends (inet);
tptr = NULL;
remaining_connections_to_sink = 0;
for (i=1;i<net[inet].num_pins;i++) { /* Need n-1 wires to connect n pins */
breadth_first_expand_trace_segment (tptr, remaining_connections_to_sink);
current = get_heap_head();
if (current == NULL) { /* Infeasible routing. No possible path for net. */
reset_path_costs (); /* Clean up before leaving. */
return (FALSE);
}
inode = current->index;
while (rr_node_route_inf[inode].target_flag == 0) {
pcost = rr_node_route_inf[inode].path_cost;
new_pcost = current->cost;
if (pcost > new_pcost) { /* New path is lowest cost. */
rr_node_route_inf[inode].path_cost = new_pcost;
prev_node = current->u.prev_node;
rr_node_route_inf[inode].prev_node = prev_node;
rr_node_route_inf[inode].prev_edge = current->prev_edge;
if (pcost > 0.99 * HUGE_FLOAT) /* First time touched. */
add_to_mod_list (&rr_node_route_inf[inode].path_cost);
breadth_first_expand_neighbours (inode, new_pcost, inet, bend_cost);
}
free_heap_data (current);
current = get_heap_head ();
if (current == NULL) { /* Impossible routing. No path for net. */
reset_path_costs ();
return (FALSE);
}
inode = current->index;
}
rr_node_route_inf[inode].target_flag--; /* Connected to this SINK. */
remaining_connections_to_sink = rr_node_route_inf[inode].target_flag;
tptr = update_traceback (current, inet);
free_heap_data (current);
}
empty_heap ();
reset_path_costs ();
return (TRUE);
}
static boolean
directed_search_route_net(int inet,
float pres_fac,
float astar_fac,
float bend_cost,
t_mst_edge ** mst)
{
/* Uses a maze routing (Dijkstra's) algorithm to route a net. The net *
* begins at the net output, and expands outward until it hits a target *
* pin. The algorithm is then restarted with the entire first wire segment *
* included as part of the source this time. For an n-pin net, the maze *
* router is invoked n-1 times to complete all the connections. Inet is *
* the index of the net to be routed. Bends are penalized by bend_cost *
* (which is typically zero for detailed routing and nonzero only for global *
* routing), since global routes with lots of bends are tougher to detailed *
* route (using a detailed router like SEGA). *
* If this routine finds that a net *cannot* be connected (due to a complete *
* lack of potential paths, rather than congestion), it returns FALSE, as *
* routing is impossible on this architecture. Otherwise it returns TRUE. */
/* WMF: This is the directed search (A-star) version of maze router. */
int inode, remaining_connections_to_sink;
int itarget, target_pin, target_node;
struct s_heap *current;
struct s_trace *new_route_start_tptr;
float old_tcost, new_tcost, old_back_cost, new_back_cost;
int highfanout_rlim;
assert(mst);
/* Rip-up any old routing. */
/* WMF: For the 1st router iteration trace_head[inet] is NULL, as it is
* my_calloc'ed in alloc_route_structs() so the following does nothing.
* However, for subsequent iterations, trace_head[inet] contains the previous
* ieration's routing for this net. */
pathfinder_update_one_cost(trace_head[inet], -1, pres_fac);
free_traceback(inet); /* kills trace, and set the trace head and tail to NULL */
/* adding the SOURCE node to the heap with correct total cost */
target_pin = mst[inet][0].to_node;
target_node = net_rr_terminals[inet][target_pin];
directed_search_add_source_to_heap(inet, target_node, astar_fac);
mark_ends(inet);
remaining_connections_to_sink = 0;
for(itarget = 0; itarget < clb_net[inet].num_sinks; itarget++)
{
target_pin = mst[inet][itarget].to_node;
target_node = net_rr_terminals[inet][target_pin];
/* printf ("Target #%d, pin number %d, target_node: %d.\n",
* itarget, target_pin, target_node); */
/* WMF: since the heap has been emptied, need to restart the wavefront
* from the current partial routing, starting at the trace_head (SOURCE)
* Note: in the 1st iteration, there is no trace (no routing at all for this net)
* i.e. trace_head[inet] == NULL (found in free_traceback() in route_common.c,
* which is called before the routing of any net),
* so this routine does nothing, but the heap does have the SOURCE node due
* to directed_search_add_source_to_heap (inet) before the loop */
highfanout_rlim = directed_search_expand_trace_segment(trace_head[inet],
target_node, astar_fac, inet,
remaining_connections_to_sink);
current = get_heap_head();
if(current == NULL)
{ /* Infeasible routing. No possible path for net. */
reset_path_costs(); /* Clean up before leaving. */
return (FALSE);
}
inode = current->index;
while(inode != target_node)
{
old_tcost = rr_node_route_inf[inode].path_cost;
new_tcost = current->cost;
/* WMF: not needed if Vaughn initialized rr_node_route_inf[inode].backward_path_cost
* to HUGE_FLOAT along with rr_node_route_inf[inode].path_cost */
if(old_tcost > 0.99 * HUGE_FLOAT) /* First time touched. */
old_back_cost = HUGE_FLOAT;
else
old_back_cost =
rr_node_route_inf[inode].backward_path_cost;
new_back_cost = current->backward_path_cost;
/* I only re-expand a node if both the "known" backward cost is lower *
* in the new expansion (this is necessary to prevent loops from *
* forming in the routing and causing havoc) *and* the expected total *
* cost to the sink is lower than the old value. Different R_upstream *
* values could make a path with lower back_path_cost less desirable *
* than one with higher cost. Test whether or not I should disallow *
* re-expansion based on a higher total cost. */
/* updating the maze (Dijktra's min dist algorithm) if found "shorter" path */
if(old_tcost > new_tcost && old_back_cost > new_back_cost)
{
/* if (old_tcost > new_tcost) { */
rr_node_route_inf[inode].prev_node =
current->u.prev_node;
rr_node_route_inf[inode].prev_edge =
current->prev_edge;
rr_node_route_inf[inode].path_cost = new_tcost;
rr_node_route_inf[inode].backward_path_cost =
new_back_cost;
if(old_tcost > 0.99 * HUGE_FLOAT) /* First time touched. */
add_to_mod_list(&rr_node_route_inf[inode].
path_cost);
directed_search_expand_neighbours(current, inet,
bend_cost,
target_node,
highfanout_rlim,
astar_fac);
}
free_heap_data(current);
current = get_heap_head();
if(current == NULL)
{ /* Impossible routing. No path for net. */
printf("Failed to route net %s #%d pin %d num_sinks %d highfanout_rlim %d\n", clb_net[inet].name, inet, itarget, clb_net[inet].num_sinks, highfanout_rlim);
reset_path_costs();
return (FALSE);
}
inode = current->index;
}
rr_node_route_inf[inode].target_flag--; /* Connected to this SINK. */
remaining_connections_to_sink =
rr_node_route_inf[inode].target_flag;
/* keep info on the current routing of this net */
new_route_start_tptr = update_traceback(current, inet);
free_heap_data(current);
/* update the congestion costs of rr_nodes due to the routing to this sink
* so only those nodes used in the partial routing of this sink and not
* of the entire net (remember we're in a loop for this net over its sinks) */
pathfinder_update_one_cost(new_route_start_tptr, 1, pres_fac);
/* WMF: MUST empty heap and recalculate all total costs, because
* for the next sink, the target destination is changed, so the expected
* cost calculation is changed also, meaning all the nodes on the heap have
* "stale" total costs (costs based on last sink). */
empty_heap();
reset_path_costs();
}
return (TRUE);
}
