boolean
try_directed_search_route(struct s_router_opts router_opts,
t_ivec ** clb_opins_used_locally,
int width_fac,
t_mst_edge ** mst)
{
/* Iterated maze router ala Pathfinder Negotiated Congestion algorithm, *
* (FPGA 95 p. 111). Returns TRUE if it can route this FPGA, FALSE if *
* it can't. */
float pres_fac;
boolean success, is_routable, rip_up_local_opins;
int itry, inet, i;
clock_t begin, end;
int bends;
int wirelength, total_wirelength, available_wirelength;
int segments;
float *sinks;
int *net_index;
sinks = my_malloc(sizeof(float) * num_nets);
net_index = my_malloc(sizeof(int) * num_nets);
for(i = 0; i < num_nets; i++) {
sinks[i] = clb_net[i].num_sinks;
net_index[i] = i;
}
heapsort(net_index, sinks, num_nets, 1);
/* char msg[100]; */
begin = clock();
/* mst not built as good as it should, ideally, just have it after placement once only
however, rr_node numbers changed when the channel width changes so forced to do it here */
if(mst)
{
for(inet = 0; inet < num_nets; inet++)
{
free(mst[inet]);
mst[inet] = get_mst_of_net(inet);
}
}
end = clock();
#ifdef CLOCKS_PER_SEC
printf("mst took %g seconds\n", (float)(end - begin) / CLOCKS_PER_SEC);
#else
printf("mst took %g seconds\n", (float)(end - begin) / CLK_PER_SEC);
#endif
/* Usually the first iteration uses a very small (or 0) pres_fac to find *
* the shortest path and get a congestion map. For fast compiles, I set *
* pres_fac high even for the first iteration. */
pres_fac = router_opts.first_iter_pres_fac;
for(itry = 1; itry <= router_opts.max_router_iterations; itry++)
{
begin = clock();
printf("routing iteration %d\n", itry);
for(i = 0; i < num_nets; i++)
{
inet = net_index[i];
if(clb_net[inet].is_global == FALSE && clb_net[inet].num_sinks != 0)
{ /* Skip global nets and empty nets (empty nets are already reserved using reserve_locally_used_opins). */
is_routable =
directed_search_route_net(inet, pres_fac,
router_opts.
astar_fac,
router_opts.
bend_cost, mst);
/* Impossible to route? (disconnected rr_graph) */
if(!is_routable)
{
printf("Routing failed.\n");
free(net_index);
free(sinks);
return (FALSE);
}
}
}
end = clock();
#ifdef CLOCKS_PER_SEC
printf("routing iteration took %g seconds\n", (float)(end - begin) / CLOCKS_PER_SEC);
#else
printf("routing iteration took %g seconds\n", (float)(end - begin) / CLK_PER_SEC);
#endif
fflush(stdout);
if(itry == 1) {
/* Early exit code for cases where it is obvious that a successful route will not be found
Heuristic: If total wirelength used in first routing iteration is X% of total available wirelength, exit
*/
total_wirelength = 0;
available_wirelength = 0;
for(i = 0; i < num_rr_nodes; i++) {
if(rr_node[i].type == CHANX || rr_node[i].type == CHANY)
{
available_wirelength += 1 + rr_node[i].xhigh - rr_node[i].xlow +
rr_node[i].yhigh - rr_node[i].ylow;
}
}
for(inet = 0; inet < num_nets; inet++)
{
if(clb_net[inet].is_global == FALSE && clb_net[inet].num_sinks != 0)
{ /* Globals don't count. */
get_num_bends_and_length(inet, &bends, &wirelength,
&segments);
total_wirelength += wirelength;
}
}
printf("wirelength after first iteration %d, total available wirelength %d, ratio %g\n", total_wirelength, available_wirelength, (float)(total_wirelength)/(float)(available_wirelength));
if((float)(total_wirelength)/(float)(available_wirelength) > FIRST_ITER_WIRELENTH_LIMIT) {
printf("Wirelength usage ratio exceeds limit of %g, fail routing\n", FIRST_ITER_WIRELENTH_LIMIT);
free(net_index);
free(sinks);
return FALSE;
}
}
/* Make sure any CLB OPINs used up by subblocks being hooked directly *
* to them are reserved for that purpose. */
if(itry == 1)
rip_up_local_opins = FALSE;
else
rip_up_local_opins = TRUE;
reserve_locally_used_opins(pres_fac, rip_up_local_opins,
clb_opins_used_locally);
success = feasible_routing();
if(success)
{
printf
("Successfully routed after %d routing iterations by Directed Search.\n",
itry);
free(net_index);
free(sinks);
return (TRUE);
}
#if 0
else
{
sprintf(msg,
"After iteration %d routing failed (A*) with a channel width factor of %d and Fc_int of %d, Fs_int of %d.",
itry, width_fac, Fc_int, Fs_int);
init_draw_coords(pins_per_clb);
update_screen(MAJOR, msg, ROUTING, FALSE);
}
#endif
if(itry == 1)
{
pres_fac = router_opts.initial_pres_fac;
pathfinder_update_cost(pres_fac, 0.); /* Acc_fac=0 for first iter. */
}
else
{
pres_fac *= router_opts.pres_fac_mult;
pathfinder_update_cost(pres_fac, router_opts.acc_fac);
}
}
printf("Routing failed.\n");
free(sinks);
free(net_index);
return (FALSE);
}
boolean
try_directed_search_route(struct s_router_opts router_opts,
t_ivec ** fb_opins_used_locally,
int width_fac,
t_mst_edge ** mst)
{
/* Iterated maze router ala Pathfinder Negotiated Congestion algorithm, *
* (FPGA 95 p. 111). Returns TRUE if it can route this FPGA, FALSE if *
* it can't. */
float pres_fac;
boolean success, is_routable, rip_up_local_opins;
int itry, inet;
/* char msg[100]; */
/* mst not built as good as it should, ideally, just have it after placement once only
however, rr_node numbers changed when the channel width changes so forced to do it here */
if(mst)
{
for(inet = 0; inet < num_nets; inet++)
{
free(mst[inet]);
mst[inet] = get_mst_of_net(inet);
}
}
/* Usually the first iteration uses a very small (or 0) pres_fac to find *
* the shortest path and get a congestion map. For fast compiles, I set *
* pres_fac high even for the first iteration. */
pres_fac = router_opts.first_iter_pres_fac;
for(itry = 1; itry <= router_opts.max_router_iterations; itry++)
{
for(inet = 0; inet < num_nets; inet++)
{
if(net[inet].is_global == FALSE)
{ /* Skip global nets. */
is_routable =
directed_search_route_net(inet, pres_fac,
router_opts.
astar_fac,
router_opts.
bend_cost, mst);
/* Impossible to route? (disconnected rr_graph) */
if(!is_routable)
{
printf("Routing failed.\n");
return (FALSE);
}
}
}
/* Make sure any FB OPINs used up by subblocks being hooked directly *
* to them are reserved for that purpose. */
if(itry == 1)
rip_up_local_opins = FALSE;
else
rip_up_local_opins = TRUE;
reserve_locally_used_opins(pres_fac, rip_up_local_opins,
fb_opins_used_locally);
success = feasible_routing();
if(success)
{
printf
("Successfully routed after %d routing iterations by Directed Search.\n",
itry);
return (TRUE);
}
#if 0
else
{
sprintf(msg,
"After iteration %d routing failed (A*) with a channel width factor of %d and Fc_int of %d, Fs_int of %d.",
itry, width_fac, Fc_int, Fs_int);
init_draw_coords(pins_per_clb);
update_screen(MAJOR, msg, ROUTING, FALSE);
}
#endif
if(itry == 1)
{
pres_fac = router_opts.initial_pres_fac;
pathfinder_update_cost(pres_fac, 0.); /* Acc_fac=0 for first iter. */
}
else
{
pres_fac *= router_opts.pres_fac_mult;
pathfinder_update_cost(pres_fac, router_opts.acc_fac);
}
}
printf("Routing failed.\n");
return (FALSE);
}
