route_tree_timing.c

用于学术研究的FPGA布局布线软件VPR

#include <stdio.h>
#include "util.h"
#include "vpr_types.h"
#include "globals.h"
#include "route_common.h"
#include "route_tree_timing.h"

/* This module keeps track of the partial routing tree for timing-driven     *
 * routing.  The normal traceback structure doesn't provide enough info      *
 * about the partial routing during timing-driven routing, so the routines   *
 * in this module are used to keep a tree representation of the partial      *
 * routing during timing-driven routing.  This allows rapid incremental      *
 * timing analysis.  The net_delay module does timing analysis in one step   *
 * (not incrementally as pieces of the routing are added).  I could probably *
 * one day remove a lot of net_delay.c and call the corresponding routines   *
 * here, but it's useful to have a from-scratch delay calculator to check    *
 * the results of this one.                                                  */


/********************** Variables local to this module ***********************/

/* Array below allows mapping from any rr_node to any rt_node currently in   *
 * the rt_tree.                                                              */

static t_rt_node **rr_node_to_rt_node = NULL;	/* [0..num_rr_nodes-1] */

/* Frees lists for fast addition and deletion of nodes and edges. */

static t_rt_node *rt_node_free_list = NULL;
static t_linked_rt_edge *rt_edge_free_list = NULL;



/********************** Subroutines local to this module *********************/

static t_rt_node *alloc_rt_node(void);

static void free_rt_node(t_rt_node * rt_node);

static t_linked_rt_edge *alloc_linked_rt_edge(void);

static void free_linked_rt_edge(t_linked_rt_edge * rt_edge);

static t_rt_node *add_path_to_route_tree(struct s_heap *hptr,
					 t_rt_node ** sink_rt_node_ptr);

static void load_new_path_R_upstream(t_rt_node * start_of_new_path_rt_node);

static t_rt_node *update_unbuffered_ancestors_C_downstream(t_rt_node
							   *
							   start_of_new_path_rt_node);

static void load_rt_subtree_Tdel(t_rt_node * subtree_rt_root,
				 float Tarrival);



/************************** Subroutine definitions ***************************/

void
alloc_route_tree_timing_structs(void)
{

/* Allocates any structures needed to build the routing trees. */

    if(rr_node_to_rt_node != NULL || rt_node_free_list != NULL ||
       rt_node_free_list != NULL)
	{
	    printf("Error in alloc_route_tree_timing_structs: old structures "
		   "already exist.\n");
	    exit(1);
	}

    rr_node_to_rt_node = (t_rt_node **) my_malloc(num_rr_nodes *
						  sizeof(t_rt_node *));
}


void
free_route_tree_timing_structs(void)
{

/* Frees the structures needed to build routing trees, and really frees      *
 * (i.e. calls free) all the data on the free lists.                         */

    t_rt_node *rt_node, *next_node;
    t_linked_rt_edge *rt_edge, *next_edge;

    free(rr_node_to_rt_node);
    rr_node_to_rt_node = NULL;

    rt_node = rt_node_free_list;

    while(rt_node != NULL)
	{
	    next_node = rt_node->u.next;
	    free(rt_node);
	    rt_node = next_node;
	}

    rt_node_free_list = NULL;

    rt_edge = rt_edge_free_list;

    while(rt_edge != NULL)
	{
	    next_edge = rt_edge->next;
	    free(rt_edge);
	    rt_edge = next_edge;
	}

    rt_edge_free_list = NULL;
}


static t_rt_node *
alloc_rt_node(void)
{

/* Allocates a new rt_node, from the free list if possible, from the free   *
 * store otherwise.                                                         */

    t_rt_node *rt_node;

    rt_node = rt_node_free_list;

    if(rt_node != NULL)
	{
	    rt_node_free_list = rt_node->u.next;
	}
    else
	{
	    rt_node = (t_rt_node *) my_malloc(sizeof(t_rt_node));
	}

    return (rt_node);
}


static void
free_rt_node(t_rt_node * rt_node)
{

/* Adds rt_node to the proper free list.          */

    rt_node->u.next = rt_node_free_list;
    rt_node_free_list = rt_node;
}


static t_linked_rt_edge *
alloc_linked_rt_edge(void)
{

/* Allocates a new linked_rt_edge, from the free list if possible, from the  *
 * free store otherwise.                                                     */

    t_linked_rt_edge *linked_rt_edge;

    linked_rt_edge = rt_edge_free_list;

    if(linked_rt_edge != NULL)
	{
	    rt_edge_free_list = linked_rt_edge->next;
	}
    else
	{
	    linked_rt_edge = (t_linked_rt_edge *) my_malloc(sizeof
							    (t_linked_rt_edge));
	}

    return (linked_rt_edge);
}


static void
free_linked_rt_edge(t_linked_rt_edge * rt_edge)
{

/* Adds the rt_edge to the rt_edge free list.                       */

    rt_edge->next = rt_edge_free_list;
    rt_edge_free_list = rt_edge;
}


t_rt_node *
init_route_tree_to_source(int inet)
{

/* Initializes the routing tree to just the net source, and returns the root *
 * node of the rt_tree (which is just the net source).                       */

    t_rt_node *rt_root;
    int inode;

    rt_root = alloc_rt_node();
    rt_root->u.child_list = NULL;
    rt_root->parent_node = NULL;
    rt_root->parent_switch = OPEN;
    rt_root->re_expand = TRUE;

    inode = net_rr_terminals[inet][0];	/* Net source */

    rt_root->inode = inode;
    rt_root->C_downstream = rr_node[inode].C;
    rt_root->R_upstream = rr_node[inode].R;
    rt_root->Tdel = 0.5 * rr_node[inode].R * rr_node[inode].C;
    rr_node_to_rt_node[inode] = rt_root;

    return (rt_root);
}


t_rt_node *
update_route_tree(struct s_heap * hptr)
{

/* Adds the most recently finished wire segment to the routing tree, and    *
 * updates the Tdel, etc. numbers for the rest of the routing tree.  hptr   *
 * is the heap pointer of the SINK that was reached.  This routine returns  *
 * a pointer to the rt_node of the SINK that it adds to the routing.        */

    t_rt_node *start_of_new_path_rt_node, *sink_rt_node;
    t_rt_node *unbuffered_subtree_rt_root, *subtree_parent_rt_node;
    float Tdel_start;
    short iswitch;

    start_of_new_path_rt_node = add_path_to_route_tree(hptr, &sink_rt_node);
    load_new_path_R_upstream(start_of_new_path_rt_node);
    unbuffered_subtree_rt_root =
	update_unbuffered_ancestors_C_downstream(start_of_new_path_rt_node);

    subtree_parent_rt_node = unbuffered_subtree_rt_root->parent_node;

    if(subtree_parent_rt_node != NULL)
	{			/* Parent exists. */
	    Tdel_start = subtree_parent_rt_node->Tdel;
	    iswitch = unbuffered_subtree_rt_root->parent_switch;
	    Tdel_start += switch_inf[iswitch].R *
		unbuffered_subtree_rt_root->C_downstream;
	    Tdel_start += switch_inf[iswitch].Tdel;
	}
    else
	{			/* Subtree starts at SOURCE */
	    Tdel_start = 0.;
	}

    load_rt_subtree_Tdel(unbuffered_subtree_rt_root, Tdel_start);

    return (sink_rt_node);
}


static t_rt_node *
add_path_to_route_tree(struct s_heap *hptr,
		       t_rt_node ** sink_rt_node_ptr)
{

/* Adds the most recent wire segment, ending at the SINK indicated by hptr, *
 * to the routing tree.  It returns the first (most upstream) new rt_node,  *
 * and (via a pointer) the rt_node of the new SINK.                         */

    int inode, remaining_connections_to_sink;
    short iedge, iswitch;
    float C_downstream;
    t_rt_node *rt_node, *downstream_rt_node, *sink_rt_node;
    t_linked_rt_edge *linked_rt_edge;


    inode = hptr->index;

#ifdef DEBUG
    if(rr_node[inode].type != SINK)
	{
	    printf
		("Error in add_path_to_route_tree.  Expected type = SINK (%d).\n",
		 SINK);
	    printf("Got type = %d.", rr_node[inode].type);
	    exit(1);
	}
#endif

    remaining_connections_to_sink = rr_node_route_inf[inode].target_flag;
    sink_rt_node = alloc_rt_node();
    sink_rt_node->u.child_list = NULL;