#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,
				   struct s_net *nets,
			       t_linked_rc_ptr * rr_node_to_rc_node);

static void load_one_constant_net_delay(float **net_delay,
					int inet,
					struct s_net *nets,
					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, struct s_net *nets, int n_nets)
{

/* 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(n_nets * sizeof(float *));

    for(inet = 0; inet < n_nets; inet++)
	{
	    tmp_ptr =
		(float *)my_chunk_malloc(((nets[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, struct s_net *nets, int n_nets)
{

/* 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 < n_nets; inet++)
	{
	    if(nets[inet].is_global)
		{
		    load_one_constant_net_delay(net_delay, inet, nets, 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, nets, 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, struct s_net *nets, int n_nets)
{

/* 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 < n_nets; inet++)
	{
	    if(nets[inet].is_global)
		{
		    load_one_constant_net_delay(net_delay, inet, nets, 0.);
		}
	    else
		{
		    load_one_constant_net_delay(net_delay, inet, nets, 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;
    linked_rc_edge->iswitch = iswitch;

    child_rc->u.child_list = NULL;
    child_rc->inode = inode;
}


static t_rc_node *
alloc_rc_node(t_rc_node ** rc_node_free_list_ptr)
{

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

    t_rc_node *rc_node;

    rc_node = *rc_node_free_list_ptr;

    if(rc_node != NULL)
	{
	    *rc_node_free_list_ptr = rc_node->u.next;
	}
    else
	{
	    rc_node = (t_rc_node *) my_malloc(sizeof(t_rc_node));
	}

    return (rc_node);
}


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

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

    rc_node->u.next = *rc_node_free_list_ptr;
    *rc_node_free_list_ptr = rc_node;
}


static t_linked_rc_edge *
alloc_linked_rc_edge(t_linked_rc_edge ** rc_edge_free_list_ptr)
{

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

    t_linked_rc_edge *linked_rc_edge;

    linked_rc_edge = *rc_edge_free_list_ptr;

    if(linked_rc_edge != NULL)
	{
	    *rc_edge_free_list_ptr = linked_rc_edge->next;
	}
    else
	{
	    linked_rc_edge = (t_linked_rc_edge *) my_malloc(sizeof
							    (t_linked_rc_edge));
	}

    return (linked_rc_edge);
}


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

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

    rc_edge->next = *rc_edge_free_list_ptr;
    *rc_edge_free_list_ptr = rc_edge;
}


static float
load_rc_tree_C(t_rc_node * rc_node)
{

/* Does a post-order traversal of the rc tree to load each node's           *
 * C_downstream with the proper sum of all the downstream capacitances.     *
 * This routine calls itself recursively to perform the traversal.          */

    t_linked_rc_edge *linked_rc_edge;
    t_rc_node *child_node;
    int inode;
    short iswitch;
    float C, C_downstream;

    linked_rc_edge = rc_node->u.child_list;
    inode = rc_node->inode;
    C = rr_node[inode].C;

    while(linked_rc_edge != NULL)
	{			/* For all children */
	    iswitch = linked_rc_edge->iswitch;
	    child_node = linked_rc_edge->child;
	    C_downstream = load_rc_tree_C(child_node);

	    if(switch_inf[iswitch].buffered == FALSE)
		C += C_downstream;

	    linked_rc_edge = linked_rc_edge->next;
	}

    rc_node->C_downstream = C;
    return (C);
}


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

/* This routine does a pre-order depth-first traversal of the rc tree to    *
 * compute the Tdel to each node in the rc tree.  The T_arrival is the time *
 * at which the signal hits the input to this node.  This routine calls     *
 * itself recursively to perform the traversal.                             */

    float Tdel, Rmetal, Tchild;
    t_linked_rc_edge *linked_rc_edge;
    t_rc_node *child_node;
    short iswitch;
    int inode;

    Tdel = T_arrival;
    inode = rc_node->inode;
    Rmetal = rr_node[inode].R;

/* NB:  rr_node[inode].C gives the capacitance of this node, while          *
 * rc_node->C_downstream gives the unbuffered downstream capacitance rooted *
 * at this node, including the C of the node itself.  I want to multiply    *
 * the C of this node by 0.5 Rmetal, since it's a distributed RC line.      *
 * Hence 0.5 Rmetal * Cnode is a pessimistic estimate of delay (i.e. end to *
 * end).  For the downstream capacitance rooted at this node (not including *
 * the capacitance of the node itself), I assume it is, on average,         *
 * connected halfway along the line, so I also multiply by 0.5 Rmetal.  To  *
 * be totally pessimistic I would multiply the downstream part of the       *
 * capacitance by Rmetal.  Play with this equation if you like.             */

/* Rmetal is distributed so x0.5 */
    Tdel += 0.5 * rc_node->C_downstream * Rmetal;
    rc_node->Tdel = Tdel;

/* Now expand the children of this node to load their Tdel values.       */

    linked_rc_edge = rc_node->u.child_list;

    while(linked_rc_edge != NULL)
	{			/* For all children */
	    iswitch = linked_rc_edge->iswitch;
	    child_node = linked_rc_edge->child;

	    Tchild = Tdel + switch_inf[iswitch].R * child_node->C_downstream;
	    Tchild += switch_inf[iswitch].Tdel;	/* Intrinsic switch delay. */
	    load_rc_tree_T(child_node, Tchild);

	    linked_rc_edge = linked_rc_edge->next;
	}
}


static void
load_one_net_delay(float **net_delay,
		   int inet,
		   struct s_net* nets,
		   t_linked_rc_ptr * rr_node_to_rc_node)
{

/* Loads the net delay array for net inet.  The rc tree for that net must  *
 * have already been completely built and loaded.                          */

    int ipin, inode;
    float Tmax;
    t_rc_node *rc_node;
    t_linked_rc_ptr *linked_rc_ptr, *next_ptr;

    for(ipin = 1; ipin < (nets[inet].num_sinks + 1); ipin++)
	{

	    inode = net_rr_terminals[inet][ipin];


	    linked_rc_ptr = rr_node_to_rc_node[inode].next;
	    rc_node = rr_node_to_rc_node[inode].rc_node;
	    Tmax = rc_node->Tdel;

	    /* If below only executes when one net connects several times to the      *
	     * same SINK.  In this case, I can't tell which net pin each connection   *
	     * to this SINK corresponds to (I can just choose arbitrarily).  To make  *
	     * sure the timing behaviour converges, I pessimistically set the delay   *
	     * for all of the connections to this SINK by this net to be the max. of  *
	     * the delays from this net to this SINK.  NB:  This code only occurs     *
	     * when a net connect more than once to the same pin class on the same    *
	     * logic block.  Only a weird architecture would allow this.              */

	    if(linked_rc_ptr != NULL)
		{

		    /* The first time I hit a multiply-used SINK, I choose the largest delay  *
		     * from this net to this SINK and use it for every connection to this     *
		     * SINK by this net.                                                      */

		    do
			{
			    rc_node = linked_rc_ptr->rc_node;
			    if(rc_node->Tdel > Tmax)
				{
				    Tmax = rc_node->Tdel;
				    rr_node_to_rc_node[inode].rc_node =
					rc_node;
				}
			    next_ptr = linked_rc_ptr->next;
			    free(linked_rc_ptr);
			    linked_rc_ptr = next_ptr;
			}
		    while(linked_rc_ptr != NULL);	/* End do while */

		    rr_node_to_rc_node[inode].next = NULL;
		}
	    /* End of if multiply-used SINK */
	    net_delay[inet][ipin] = Tmax;
	}
}


static void
load_one_constant_net_delay(float **net_delay,
			    int inet, 
				struct s_net *nets,
			    float delay_value)
{

/* Sets each entry of the net_delay array for net inet to delay_value.     */

    int ipin;

    for(ipin = 1; ipin < (nets[inet].num_sinks + 1); ipin++)
	net_delay[inet][ipin] = 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)
{

/* Puts the rc tree pointed to by rc_root back on the free list.  Depth-     *
 * first post-order traversal via recursion.                                 */

    t_rc_node *rc_node, *child_node;
    t_linked_rc_edge *rc_edge, *next_edge;

    rc_node = rc_root;
    rc_edge = rc_node->u.child_list;

    while(rc_edge != NULL)
	{			/* For all children */
	    child_node = rc_edge->child;
	    free_rc_tree(child_node, rc_node_free_list_ptr,
			 rc_edge_free_list_ptr);
	    next_edge = rc_edge->next;
	    free_linked_rc_edge(rc_edge, rc_edge_free_list_ptr);
	    rc_edge = next_edge;
	}

    free_rc_node(rc_node, rc_node_free_list_ptr);
}


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

/* Resets the rr_node_to_rc_node mapping entries that were set during       *
 * construction of the RC tree for net inet.  Any extra linked list entries *
 * added to deal with a SINK being connected to multiple times have already *
 * been freed by load_one_net_delay.                                        */

    struct s_trace *tptr;
    int inode;

    tptr = trace_head[inet];

    while(tptr != NULL)
	{
	    inode = tptr->index;
	    rr_node_to_rc_node[inode].rc_node = NULL;
	    tptr = tptr->next;
	}
}


static void
free_rc_node_free_list(t_rc_node * rc_node_free_list)
{

/* Really frees (i.e. calls free()) all the rc_nodes on the free list.   */

    t_rc_node *rc_node, *next_node;

    rc_node = rc_node_free_list;

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


static void
free_rc_edge_free_list(t_linked_rc_edge * rc_edge_free_list)
{

/* Really frees (i.e. calls free()) all the rc_edges on the free list.   */

    t_linked_rc_edge *rc_edge, *next_edge;

    rc_edge = rc_edge_free_list;

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


void
print_net_delay(float **net_delay,
		char *fname, struct s_net *nets, int n_nets)
{

/* Dumps the net delays into file fname.   */

    FILE *fp;
    int inet, ipin;

    fp = my_fopen(fname, "w", 0);

    for(inet = 0; inet < n_nets; inet++)
	{
	    fprintf(fp, "Net: %d.\n", inet);
	    fprintf(fp, "Delays:");

	    for(ipin = 1; ipin < (nets[inet].num_sinks + 1); ipin++)
		fprintf(fp, " %g", net_delay[inet][ipin]);

	    fprintf(fp, "\n\n");
	}

    fclose(fp);
}