net_delay.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 "net_delay.h"


/***************** Types and defines local to this module ********************/

struct s_linked_rc_edge
{
    struct s_rc_node *child;
    short iswitch;
    struct s_linked_rc_edge *next;
};

typedef struct s_linked_rc_edge t_linked_rc_edge;

/* Linked list listing the children of an rc_node.                           *
 * child:  Pointer to an rc_node (child of the current node).                *
 * iswitch:  Index of the switch type used to connect to the child node.     *
 * next:   Pointer to the next linked_rc_edge in the linked list (allows     *
 *         you to get the next child of the current rc_node).                */



struct s_rc_node
{
    union
    {
	t_linked_rc_edge *child_list;
	struct s_rc_node *next;
    }
    u;
    int inode;
    float C_downstream;
    float Tdel;
};

typedef struct s_rc_node t_rc_node;

/* Structure describing one node in an RC tree (used to get net delays).     *
 * u.child_list:  Pointer to a linked list of linked_rc_edge.  Each one of   *
 *                the linked list entries gives a child of this node.        *
 * u.next:  Used only when this node is on the free list.  Gives the next    *
 *          node on the free list.                                           *
 * inode:  index (ID) of the rr_node that corresponds to this rc_node.       *
 * C_downstream:  Total downstream capacitance from this rc_node.  That is,  *
 *                the total C of the subtree rooted at the current node,     *
 *                including the C of the current node.                       *
 * Tdel:  Time delay for the signal to get from the net source to this node. *
 *        Includes the time to go through this node.                         */


struct s_linked_rc_ptr
{
    struct s_rc_node *rc_node;
    struct s_linked_rc_ptr *next;
};

typedef struct s_linked_rc_ptr t_linked_rc_ptr;

/* Linked list of pointers to rc_nodes.                                      *
 * rc_node:  Pointer to an rc_node.                                          *
 * next:  Next list element.                                                 */



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

static t_rc_node *alloc_and_load_rc_tree(int inet,
					 t_rc_node ** rc_node_free_list_ptr,
					 t_linked_rc_edge **
					 rc_edge_free_list_ptr,
					 t_linked_rc_ptr *
					 rr_node_to_rc_node);

static void add_to_rc_tree(t_rc_node * parent_rc,
			   t_rc_node * child_rc,
			   short iswitch,
			   int inode,
			   t_linked_rc_edge ** rc_edge_free_list_ptr);

static t_rc_node *alloc_rc_node(t_rc_node ** rc_node_free_list_ptr);

static void free_rc_node(t_rc_node * rc_node,
			 t_rc_node ** rc_node_free_list_ptr);

static t_linked_rc_edge *alloc_linked_rc_edge(t_linked_rc_edge
					      ** rc_edge_free_list_ptr);

static void free_linked_rc_edge(t_linked_rc_edge * rc_edge,
				t_linked_rc_edge ** rc_edge_free_list_ptr);

static float load_rc_tree_C(t_rc_node * rc_node);

static void load_rc_tree_T(t_rc_node * rc_node,
			   float T_arrival);

static void load_one_net_delay(float **net_delay,
			       int inet,
			       t_linked_rc_ptr * rr_node_to_rc_node);

static void load_one_constant_net_delay(float **net_delay,
					int inet,
					float delay_value);

static void free_rc_tree(t_rc_node * rc_root,
			 t_rc_node ** rc_node_free_list_ptr,
			 t_linked_rc_edge ** rc_edge_free_list_ptr);

static void reset_rr_node_to_rc_node(t_linked_rc_ptr * rr_node_to_rc_node,
				     int inet);

static void free_rc_node_free_list(t_rc_node * rc_node_free_list);

static void free_rc_edge_free_list(t_linked_rc_edge * rc_edge_free_list);



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


float **
alloc_net_delay(struct s_linked_vptr **chunk_list_head_ptr)
{

/* Allocates space for the net_delay data structure                          *
 * [0..num_nets-1][1..num_pins-1].  I chunk the data to save space on large  *
 * problems.                                                                 */

    float **net_delay;		/* [0..num_nets-1][1..num_pins-1] */
    float *tmp_ptr;
    int inet;
    int chunk_bytes_avail;
    char *chunk_next_avail_mem;

    *chunk_list_head_ptr = NULL;
    chunk_bytes_avail = 0;
    chunk_next_avail_mem = NULL;

    net_delay = (float **)my_malloc(num_nets * sizeof(float *));

    for(inet = 0; inet < num_nets; inet++)
	{
	    tmp_ptr =
		(float *)my_chunk_malloc(((net[inet].num_sinks + 1) - 1) *
					 sizeof(float), chunk_list_head_ptr,
					 &chunk_bytes_avail,
					 &chunk_next_avail_mem);
		
	    net_delay[inet] = tmp_ptr - 1;	/* [1..num_pins-1] */
	}

    return (net_delay);
}


void
free_net_delay(float **net_delay,
	       struct s_linked_vptr **chunk_list_head_ptr)
{

/* Frees the net_delay structure.  Assumes it was chunk allocated.          */

    free(net_delay);
    free_chunk_memory(*chunk_list_head_ptr);
    *chunk_list_head_ptr = NULL;
}


void
load_net_delay_from_routing(float **net_delay)
{

/* This routine loads net_delay[0..num_nets-1][1..num_pins-1].  Each entry   *
 * is the Elmore delay from the net source to the appropriate sink.  Both    *
 * the rr_graph and the routing traceback must be completely constructed     *
 * before this routine is called, and the net_delay array must have been     *
 * allocated.                                                                */

    t_rc_node *rc_node_free_list, *rc_root;
    t_linked_rc_edge *rc_edge_free_list;
    int inet;
    t_linked_rc_ptr *rr_node_to_rc_node;	/* [0..num_rr_nodes-1]  */

    rr_node_to_rc_node = (t_linked_rc_ptr *) my_calloc(num_rr_nodes,
						       sizeof
						       (t_linked_rc_ptr));

    rc_node_free_list = NULL;
    rc_edge_free_list = NULL;

    for(inet = 0; inet < num_nets; inet++)
	{
	    if(net[inet].is_global)
		{
		    load_one_constant_net_delay(net_delay, inet, 0.);
		}
	    else
		{
		    rc_root = alloc_and_load_rc_tree(inet, &rc_node_free_list,
						     &rc_edge_free_list,
						     rr_node_to_rc_node);
		    load_rc_tree_C(rc_root);
		    load_rc_tree_T(rc_root, 0.);
		    load_one_net_delay(net_delay, inet, rr_node_to_rc_node);
		    free_rc_tree(rc_root, &rc_node_free_list,
				 &rc_edge_free_list);
		    reset_rr_node_to_rc_node(rr_node_to_rc_node, inet);
		}
	}

    free_rc_node_free_list(rc_node_free_list);
    free_rc_edge_free_list(rc_edge_free_list);
    free(rr_node_to_rc_node);
}


void
load_constant_net_delay(float **net_delay,
			float delay_value)
{

/* Loads the net_delay array with delay_value for every source - sink        *
 * connection that is not on a global resource, and with 0. for every source *
 * - sink connection on a global net.  (This can be used to allow timing     *
 * analysis before routing is done with a constant net delay model).         */

    int inet;

    for(inet = 0; inet < num_nets; inet++)
	{
	    if(net[inet].is_global)
		{
		    load_one_constant_net_delay(net_delay, inet, 0.);
		}
	    else
		{
		    load_one_constant_net_delay(net_delay, inet, delay_value);
		}
	}
}


static t_rc_node *
alloc_and_load_rc_tree(int inet,
		       t_rc_node ** rc_node_free_list_ptr,
		       t_linked_rc_edge ** rc_edge_free_list_ptr,
		       t_linked_rc_ptr * rr_node_to_rc_node)
{

/* Builds a tree describing the routing of net inet.  Allocates all the data *
 * and inserts all the connections in the tree.                              */

    t_rc_node *curr_rc, *prev_rc, *root_rc;
    struct s_trace *tptr;
    int inode, prev_node;
    short iswitch;
    t_linked_rc_ptr *linked_rc_ptr;

    root_rc = alloc_rc_node(rc_node_free_list_ptr);
    tptr = trace_head[inet];

    if(tptr == NULL)
	{
	    printf
		("Error in alloc_and_load_rc_tree:  Traceback for net %d doesn't "
		 "exist.\n", inet);
	    exit(1);
	}

    inode = tptr->index;
    iswitch = tptr->iswitch;
    root_rc->inode = inode;
    root_rc->u.child_list = NULL;
    rr_node_to_rc_node[inode].rc_node = root_rc;

    prev_rc = root_rc;
    tptr = tptr->next;

    while(tptr != NULL)
	{
	    inode = tptr->index;

/* Is this node a "stitch-in" point to part of the existing routing or a   *
 * new piece of routing along the current routing "arm?"                   */

	    if(rr_node_to_rc_node[inode].rc_node == NULL)
		{		/* Part of current "arm" */
		    curr_rc = alloc_rc_node(rc_node_free_list_ptr);
		    add_to_rc_tree(prev_rc, curr_rc, iswitch, inode,
				   rc_edge_free_list_ptr);
		    rr_node_to_rc_node[inode].rc_node = curr_rc;
		    prev_rc = curr_rc;
		}

	    else if(rr_node[inode].type != SINK)
		{		/* Connection to old stuff. */

#ifdef DEBUG
		    prev_node = prev_rc->inode;
		    if(rr_node[prev_node].type != SINK)
			{
			    printf
				("Error in alloc_and_load_rc_tree:  Routing of net %d is "
				 "not a tree.\n", inet);
			    exit(1);
			}
#endif

		    prev_rc = rr_node_to_rc_node[inode].rc_node;
		}

	    else
		{		/* SINK that this net has connected to more than once. */

		    /* I can connect to a SINK node more than once in some weird architectures. *
		     * That means the routing isn't really a tree -- there is reconvergent      *
		     * fanout from two or more IPINs into one SINK.  I convert this structure   *
		     * into a true RC tree on the fly by creating a new rc_node each time I hit *
		     * the same sink.  This means I need to keep a linked list of the rc_nodes  *
		     * associated with the rr_node (inode) associated with that SINK.           */

		    curr_rc = alloc_rc_node(rc_node_free_list_ptr);
		    add_to_rc_tree(prev_rc, curr_rc, iswitch, inode,
				   rc_edge_free_list_ptr);

		    linked_rc_ptr = (t_linked_rc_ptr *)
			my_malloc(sizeof(t_linked_rc_ptr));
		    linked_rc_ptr->next = rr_node_to_rc_node[inode].next;
		    rr_node_to_rc_node[inode].next = linked_rc_ptr;
		    linked_rc_ptr->rc_node = curr_rc;

		    prev_rc = curr_rc;
		}
	    iswitch = tptr->iswitch;
	    tptr = tptr->next;
	}

    return (root_rc);
}


static void
add_to_rc_tree(t_rc_node * parent_rc,
	       t_rc_node * child_rc,
	       short iswitch,
	       int inode,
	       t_linked_rc_edge ** rc_edge_free_list_ptr)
{

/* Adds child_rc to the child list of parent_rc, and sets the switch between *
 * them to iswitch.  This routine also intitializes the child_rc properly    *
 * and sets its node value to inode.                                         */

    t_linked_rc_edge *linked_rc_edge;

    linked_rc_edge = alloc_linked_rc_edge(rc_edge_free_list_ptr);

    linked_rc_edge->next = parent_rc->u.child_list;
    parent_rc->u.child_list = linked_rc_edge;

    linked_rc_edge->child = child_rc;