SRC/timing_place_lookup.c

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#include <stdio.h>
#include <math.h>
#include <string.h>
#include "util.h"
#include "vpr_types.h"
#include "globals.h"
#include "route_common.h"
#include "place_and_route.h"
#include "route_tree_timing.h"
#include "route_timing.h"
#include "timing_place_lookup.h"
#include "rr_graph.h"
#include "mst.h"
#include "route_export.h"
#include <assert.h>


/*this file contains routines that generate the array containing*/
/*the delays between blocks, this is used in the timing driven  */
/*placement routines */

/*To compute delay between blocks we place temporary blocks at */
/*different locations in the FPGA and route nets  between      */
/*the blocks.  From this procedure we generate a lookup table  */
/*which tells us the delay between different locations in      */
/*the FPGA */

/*Note: these routines assume that there is a uniform and even */
/*distribution of the different wire segments. If this is not  */
/*the case, then this lookup table will be off */

/*Note: This code removes all heterogeneous types and creates an
artificial 1x1 tile.  A good lookup for heterogeniety 
requires more research */

#define NET_COUNT 1             /*we only use one net in these routines,   */
                    /*it is repeatedly routed and ripped up    */
                    /*to compute delays between different      */
                    /*locations, this value should not change  */
#define NET_USED 0              /*we use net at location zero of the net    */
                   /*structure                                 */
#define NET_USED_SOURCE_BLOCK 0 /*net.block[0] is source block */
#define NET_USED_SINK_BLOCK 1   /*net.block[1] is sink block */
#define SOURCE_BLOCK 0          /*block[0] is source */
#define SINK_BLOCK 1            /*block[1] is sink */

#define BLOCK_COUNT 2           /*use 2 blocks to compute delay between  */
                      /*the various FPGA locations             */
                      /*do not change this number unless you   */
                      /*really know what you are doing, it is  */
                      /*assumed that the net only connects to  */
                      /*two blocks */

#define NUM_TYPES_USED 3        /* number of types used in look up */

#define DEBUG_TIMING_PLACE_LOOKUP       /*initialize arrays to known state */

#define DUMPFILE "lookup_dump.echo"
/* #define PRINT_ARRAYS *//*only used during debugging, calls routine to  */
                     /*print out the various lookup arrays           */

/***variables that are exported to other modules***/

/*the delta arrays are used to contain the best case routing delay */
/*between different locations on the FPGA. */


float **delta_io_to_fb;
float **delta_fb_to_fb;
float **delta_fb_to_io;
float **delta_io_to_io;


/*** Other Global Arrays ******/
/* I could have allocated these as local variables, and passed them all */
/* around, but was too lazy, since this is a small file, it should not  */
/* be a big problem */

static float **net_delay;
static float **net_slack;
static float *pin_criticality;
static int *sink_order;
static t_rt_node **rt_node_of_sink;
static t_type_ptr IO_TYPE_BACKUP;
static t_type_ptr EMPTY_TYPE_BACKUP;
static t_type_ptr FILL_TYPE_BACKUP;
static t_type_descriptor dummy_type_descriptors[NUM_TYPES_USED];
static t_type_descriptor *type_descriptors_backup;
static struct s_grid_tile **grid_backup;
static int num_types_backup;

static t_ivec **clb_opins_used_locally;

#ifdef PRINT_ARRAYS
static FILE *lookup_dump;       /* If debugging mode is on, print out to
                                 * the file defined in DUMPFILE */
#endif /* PRINT_ARRAYS */

/*** Function Prototypes *****/

static void alloc_net(void);

static void alloc_block(void);

static void load_simplified_device(void);
static void restore_original_device(void);

static void alloc_and_assign_internal_structures(struct s_net **original_net,
                                                 struct s_block
                                                 **original_block,
                                                 int *original_num_nets,
                                                 int *original_num_blocks);

static void free_and_reset_internal_structures(struct s_net *original_net,
                                               struct s_block *original_block,
                                               int original_num_nets,
                                               int original_num_blocks);

static void setup_chan_width(struct s_router_opts router_opts,
                             t_chan_width_dist chan_width_dist);

static void alloc_routing_structs(struct s_router_opts router_opts,
                                  struct s_det_routing_arch det_routing_arch,
                                  t_segment_inf * segment_inf,
                                  t_timing_inf timing_inf,
                                  t_subblock_data subblock_data);

static void free_routing_structs(struct s_router_opts router_opts,
                                 struct s_det_routing_arch det_routing_arch,
                                 t_segment_inf * segment_inf,
                                 t_timing_inf timing_inf);

static void assign_locations(t_type_ptr source_type,
                             int source_x_loc,
                             int source_y_loc,
                             int source_z_loc,
                             t_type_ptr sink_type,
                             int sink_x_loc,
                             int sink_y_loc,
                             int sink_z_loc);

static float assign_blocks_and_route_net(t_type_ptr source_type,
                                         int source_x_loc,
                                         int source_y_loc,
                                         t_type_ptr sink_type,
                                         int sink_x_loc,
                                         int sink_y_loc,
                                         struct s_router_opts router_opts,
                                         struct s_det_routing_arch
                                         det_routing_arch,
                                         t_segment_inf * segment_inf,
                                         t_timing_inf timing_inf);

static void alloc_delta_arrays(void);

static void free_delta_arrays(void);

static void generic_compute_matrix(float ***matrix_ptr,
                                   t_type_ptr source_type,
                                   t_type_ptr sink_type,
                                   int source_x,
                                   int source_y,
                                   int start_x,
                                   int end_x,
                                   int start_y,
                                   int end_y,
                                   struct s_router_opts router_opts,
                                   struct s_det_routing_arch det_routing_arch,
                                   t_segment_inf * segment_inf,
                                   t_timing_inf timing_inf);

static void compute_delta_fb_to_fb(struct s_router_opts router_opts,
                                   struct s_det_routing_arch det_routing_arch,
                                   t_segment_inf * segment_inf,
                                   t_timing_inf timing_inf,
                                   int longest_length);

static void compute_delta_io_to_fb(struct s_router_opts router_opts,
                                   struct s_det_routing_arch det_routing_arch,
                                   t_segment_inf * segment_inf,
                                   t_timing_inf timing_inf);

static void compute_delta_fb_to_io(struct s_router_opts router_opts,
                                   struct s_det_routing_arch det_routing_arch,
                                   t_segment_inf * segment_inf,
                                   t_timing_inf timing_inf);

static void compute_delta_io_to_io(struct s_router_opts router_opts,
                                   struct s_det_routing_arch det_routing_arch,
                                   t_segment_inf * segment_inf,
                                   t_timing_inf timing_inf);

static void compute_delta_arrays(struct s_router_opts router_opts,
                                 struct s_det_routing_arch det_routing_arch,
                                 t_segment_inf * segment_inf,
                                 t_timing_inf timing_inf,
                                 int longest_length);

static int get_first_pin(enum e_pin_type pintype,
                         t_type_ptr type);

static int get_longest_segment_length(struct s_det_routing_arch
                                      det_routing_arch,
                                      t_segment_inf * segment_inf);
static void reset_placement(void);

#ifdef PRINT_ARRAYS
static void print_array(float **array_to_print,
                        int x1,
                        int x2,
                        int y1,
                        int y2);
#endif
/**************************************/
static int
get_first_pin(enum e_pin_type pintype,
              t_type_ptr type)
{

    /*this code assumes logical equivilance between all driving pins */
    /*global pins are not hooked up to the temporary net */

    int i, currpin;

    currpin = 0;
    for(i = 0; i < type->num_class; i++)
        {
            if(type->class_inf[i].type == pintype
               && !type->is_global_pin[currpin])
                return (type->class_inf[i].pinlist[0]);
            else
                currpin += type->class_inf[i].num_pins;
        }
    assert(0);
    exit(0);                    /*should never hit this line */
}

/**************************************/
static int
get_longest_segment_length(struct s_det_routing_arch det_routing_arch,
                           t_segment_inf * segment_inf)
{

    int i, length;

    length = 0;
    for(i = 0; i < det_routing_arch.num_segment; i++)
        {
            if(segment_inf[i].length > length)
                length = segment_inf[i].length;
        }
    return (length);
}

/**************************************/
static void
alloc_net(void)
{

    int i, len;

    net = (struct s_net *)my_malloc(num_nets * sizeof(struct s_net));
    for(i = 0; i < NET_COUNT; i++)
        {
            /* FIXME: We *really* shouldn't be allocating write-once copies */
            len = strlen("TEMP_NET");
            net[i].name = (char *)my_malloc((len + 1) * sizeof(char));
            net[i].is_global = FALSE;
            strcpy(net[NET_USED].name, "TEMP_NET");

            net[i].num_sinks = (BLOCK_COUNT - 1);
            net[i].node_block = (int *)my_malloc(BLOCK_COUNT * sizeof(int));
            net[i].node_block[NET_USED_SOURCE_BLOCK] = NET_USED_SOURCE_BLOCK;   /*driving block */
            net[i].node_block[NET_USED_SINK_BLOCK] = NET_USED_SINK_BLOCK;       /*target block */

            net[i].node_block_pin =
                (int *)my_malloc(BLOCK_COUNT * sizeof(int));
            /*the values for this are allocated in assign_blocks_and_route_net */

        }
}

/**************************************/
static void
alloc_block(void)
{

    /*allocates block structure, and assigns values to known parameters */
    /*type and x,y fields are left undefined at this stage since they  */
    /*are not known until we start moving blocks through the clb array */

    int ix_b, ix_p, len, i;
    int max_pins;

    max_pins = 0;
    for(i = 0; i < NUM_TYPES_USED; i++)
        {
            max_pins = max(max_pins, type_descriptors[i].num_pins);
        }

    block = (struct s_block *)my_malloc(num_blocks * sizeof(struct s_block));

    for(ix_b = 0; ix_b < BLOCK_COUNT; ix_b++)
        {
            len = strlen("TEMP_BLOCK");
            block[ix_b].name = (char *)my_malloc((len + 1) * sizeof(char));
            strcpy(block[ix_b].name, "TEMP_BLOCK");

            block[ix_b].nets = (int *)my_malloc(max_pins * sizeof(int));
            block[ix_b].nets[0] = 0;
            for(ix_p = 1; ix_p < max_pins; ix_p++)
                block[ix_b].nets[ix_p] = OPEN;
        }
}

/**************************************/
static void
load_simplified_device(void)
{
    int i, j;

    /* Backup original globals */
    EMPTY_TYPE_BACKUP = EMPTY_TYPE;
    IO_TYPE_BACKUP = IO_TYPE;
    FILL_TYPE_BACKUP = FILL_TYPE;
    type_descriptors_backup = type_descriptors;
    num_types_backup = num_types;
    num_types = NUM_TYPES_USED;

    /* Fill in homogeneous core type info */
    dummy_type_descriptors[0] = *EMPTY_TYPE;
    dummy_type_descriptors[0].index = 0;
    dummy_type_descriptors[1] = *IO_TYPE;
    dummy_type_descriptors[1].index = 1;
    dummy_type_descriptors[2] = *FILL_TYPE;
    dummy_type_descriptors[2].index = 2;
    type_descriptors = dummy_type_descriptors;
    EMPTY_TYPE = &dummy_type_descriptors[0];
    IO_TYPE = &dummy_type_descriptors[1];
    FILL_TYPE = &dummy_type_descriptors[2];

    /* Fill in homogeneous core grid info */
    grid_backup = grid;
    grid =
        (struct s_grid_tile **)alloc_matrix(0, nx + 1, 0, ny + 1,
                                            sizeof(struct s_grid_tile));
    for(i = 0; i < nx + 2; i++)
        {
            for(j = 0; j < ny + 2; j++)
                {
                    if((i == 0 && j == 0) ||
                       (i == nx + 1 && j == 0) ||
                       (i == 0 && j == ny + 1) || (i == nx + 1
                                                   && j == ny + 1))
                        {
                            grid[i][j].type = EMPTY_TYPE;
                        }
                    else if(i == 0 || i == nx + 1 || j == 0 || j == ny + 1)
                        {
                            grid[i][j].type = IO_TYPE;
                        }
                    else
                        {
                            grid[i][j].type = FILL_TYPE;
                        }
                    grid[i][j].blocks =
                        my_malloc(grid[i][j].type->capacity * sizeof(int));
                    grid[i][j].offset = 0;
                }
        }
}
static void
restore_original_device(void)
{
    int i, j;

    /* restore previous globals */
    IO_TYPE = IO_TYPE_BACKUP;
    EMPTY_TYPE = EMPTY_TYPE_BACKUP;
    FILL_TYPE = FILL_TYPE_BACKUP;
    type_descriptors = type_descriptors_backup;
    num_types = num_types_backup;

    /* free allocatd data */
    for(i = 0; i < nx + 2; i++)
        {
            for(j = 0; j < ny + 2; j++)
                {
                    free(grid[i][j].blocks);
                }
        }
    free_matrix(grid, 0, nx + 1, 0, sizeof(struct s_grid_tile));
    grid = grid_backup;
}

/**************************************/
static void
reset_placement(void)
{
    int i, j, k;

    for(i = 0; i <= nx + 1; i++)
        {
            for(j = 0; j <= ny + 1; j++)
                {
                    grid[i][j].usage = 0;
                    for(k = 0; k < grid[i][j].type->capacity; k++)
                        {
                            grid[i][j].blocks[k] = EMPTY;
                        }
                }
        }
}

/**************************************/
static void
alloc_and_assign_internal_structures(struct s_net **original_net,
                                     struct s_block **original_block,
                                     int *original_num_nets,
                                     int *original_num_blocks)
{
    /*allocate new data structures to hold net, and block info */

    *original_net = net;
    *original_num_nets = num_nets;
    num_nets = NET_COUNT;
    alloc_net();

    *original_block = block;
    *original_num_blocks = num_blocks;
    num_blocks = BLOCK_COUNT;
    alloc_block();


    /* [0..num_nets-1][1..num_pins-1] */
    net_delay =
        (float **)alloc_matrix(0, NET_COUNT - 1, 1, BLOCK_COUNT - 1,
                               sizeof(float));
    net_slack =
        (float **)alloc_matrix(0, NET_COUNT - 1, 1, BLOCK_COUNT - 1,
                               sizeof(float));

    reset_placement();
}

/**************************************/
static void
free_and_reset_internal_structures(struct s_net *original_net,
                                   struct s_block *original_block,
                                   int original_num_nets,
                                   int original_num_blocks)
{
    /*reset gloabal data structures to the state that they were in before these */
    /*lookup computation routines were called */

    int i;


    /*there should be only one net to free, but this is safer */
    for(i = 0; i < NET_COUNT; i++)
        {
            free(net[i].name);
            free(net[i].node_block);
            free(net[i].node_block_pin);
        }
    free(net);
    net = original_net;

    for(i = 0; i < BLOCK_COUNT; i++)
        {
            free(block[i].name);
            free(block[i].nets);
        }
    free(block);
    block = original_block;

    num_nets = original_num_nets;
    num_blocks = original_num_blocks;

    free_matrix(net_delay, 0, NET_COUNT - 1, 1, sizeof(float));
    free_matrix(net_slack, 0, NET_COUNT - 1, 1, sizeof(float));

}

/**************************************/
static void
setup_chan_width(struct s_router_opts router_opts,
                 t_chan_width_dist chan_width_dist)
{
    /*we give plenty of tracks, this increases routability for the */
    /*lookup table generation */

    int width_fac, i, max_pins_per_fb;

    max_pins_per_fb = 0;
    for(i = 0; i < num_types; i++)
        {
            max_pins_per_fb =
                max(max_pins_per_fb, type_descriptors[i].num_pins);
        }

    if(router_opts.fixed_channel_width == NO_FIXED_CHANNEL_WIDTH)
        width_fac = 4 * max_pins_per_fb;        /*this is 2x the value that binary search starts */
    /*this should be enough to allow most pins to   */
    /*connect to tracks in the architecture */
    else
        width_fac = router_opts.fixed_channel_width;

    init_chan(width_fac, chan_width_dist);
}

/**************************************/
static void
alloc_routing_structs(struct s_router_opts router_opts,
                      struct s_det_routing_arch det_routing_arch,
                      t_segment_inf * segment_inf,
                      t_timing_inf timing_inf,
                      t_subblock_data subblock_data)
{

    int bb_factor;
    int warnings;
    t_graph_type graph_type;
    
    /*calls routines that set up routing resource graph and associated structures */


    /*must set up dummy blocks for the first pass through to setup locally used opins */
    /* Only one block per tile */
    assign_locations(FILL_TYPE, 1, 1, 0, FILL_TYPE, nx, ny, 0);

    clb_opins_used_locally = alloc_route_structs(subblock_data);

    free_rr_graph();
        
        if(router_opts.route_type == GLOBAL) {
                graph_type = GRAPH_GLOBAL;
        } else {
                graph_type = (det_routing_arch.directionality ==
                    BI_DIRECTIONAL ? GRAPH_BIDIR : GRAPH_UNIDIR);
        }
    
        build_rr_graph(graph_type, num_types, dummy_type_descriptors, nx,
                       ny, grid, chan_width_x[0], NULL,
                       det_routing_arch.switch_block_type,
                           det_routing_arch.Fs, det_routing_arch.num_segment, det_routing_arch.num_switch,
                       segment_inf, det_routing_arch.global_route_switch,
                       det_routing_arch.delayless_switch, timing_inf,
                       det_routing_arch.wire_to_ipin_switch,
                       router_opts.base_cost_type, &warnings);

    alloc_and_load_rr_node_route_structs();

    alloc_timing_driven_route_structs(&pin_criticality, &sink_order,
                                      &rt_node_of_sink);


    bb_factor = nx + ny;        /*set it to a huge value */
    init_route_structs(bb_factor);
}

/**************************************/
static void
free_routing_structs(struct s_router_opts router_opts,
                     struct s_det_routing_arch det_routing_arch,
                     t_segment_inf * segment_inf,
                     t_timing_inf timing_inf)
{
    free_rr_graph();

    free_rr_node_route_structs();
    free_route_structs(clb_opins_used_locally);
    free_trace_structs();

    free_timing_driven_route_structs(pin_criticality, sink_order,
                                     rt_node_of_sink);
}

/**************************************/
static void
assign_locations(t_type_ptr source_type,
                 int source_x_loc,
                 int source_y_loc,
                 int source_z_loc,
                 t_type_ptr sink_type,
                 int sink_x_loc,
                 int sink_y_loc,
                 int sink_z_loc)
{
    /*all routing occurs between block 0 (source) and block 1 (sink) */
    block[SOURCE_BLOCK].type = source_type;
    block[SOURCE_BLOCK].x = source_x_loc;
    block[SOURCE_BLOCK].y = source_y_loc;
    block[SOURCE_BLOCK].z = source_z_loc;

    block[SINK_BLOCK].type = sink_type;
    block[SINK_BLOCK].x = sink_x_loc;
    block[SINK_BLOCK].y = sink_y_loc;
    block[SINK_BLOCK].z = sink_z_loc;

    grid[source_x_loc][source_y_loc].blocks[source_z_loc] = SOURCE_BLOCK;
    grid[sink_x_loc][sink_y_loc].blocks[sink_z_loc] = SINK_BLOCK;

    net[NET_USED].node_block_pin[NET_USED_SOURCE_BLOCK] =
        get_first_pin(DRIVER, block[SOURCE_BLOCK].type);
    net[NET_USED].node_block_pin[NET_USED_SINK_BLOCK] =
        get_first_pin(RECEIVER, block[SINK_BLOCK].type);

    grid[source_x_loc][source_y_loc].usage += 1;
    grid[sink_x_loc][sink_y_loc].usage += 1;

}

/**************************************/
static float
assign_blocks_and_route_net(t_type_ptr source_type,
                            int source_x_loc,
                            int source_y_loc,
                            t_type_ptr sink_type,
                            int sink_x_loc,
                            int sink_y_loc,
                            struct s_router_opts router_opts,
                            struct s_det_routing_arch det_routing_arch,
                            t_segment_inf * segment_inf,
                            t_timing_inf timing_inf)
{
    /*places blocks at the specified locations, and routes a net between them */
    /*returns the delay of this net */
    boolean is_routeable;
    int ipin;
    float pres_fac, T_crit;
    float net_delay_value;

    int source_z_loc, sink_z_loc;

    /* Only one block per tile */
    source_z_loc = 0;
    sink_z_loc = 0;

    net_delay_value = IMPOSSIBLE;       /*set to known value for debug purposes */

    assign_locations(source_type, source_x_loc, source_y_loc, source_z_loc,
                     sink_type, sink_x_loc, sink_y_loc, sink_z_loc);

    load_net_rr_terminals(rr_node_indices);

    T_crit = 1;
    pres_fac = 0;               /* ignore congestion */

    for(ipin = 1; ipin <= net[NET_USED].num_sinks; ipin++)
        net_slack[NET_USED][ipin] = 0;

    is_routeable = timing_driven_route_net(NET_USED, pres_fac,
                                           router_opts.max_criticality,
                                           router_opts.criticality_exp,
                                           router_opts.astar_fac,
                                           router_opts.bend_cost,
                                           net_slack[NET_USED],
                                           pin_criticality, sink_order,
                                           rt_node_of_sink, T_crit,
                                           net_delay[NET_USED]);

    net_delay_value = net_delay[NET_USED][NET_USED_SINK_BLOCK];

    grid[source_x_loc][source_y_loc].usage = 0;
    grid[source_x_loc][source_y_loc].blocks[source_z_loc] = EMPTY;
    grid[sink_x_loc][sink_y_loc].usage = 0;
    grid[sink_x_loc][sink_y_loc].blocks[sink_z_loc] = EMPTY;

    return (net_delay_value);
}

/**************************************/
static void
alloc_delta_arrays(void)
{
    int id_x, id_y;

    delta_fb_to_fb =
        (float **)alloc_matrix(0, nx - 1, 0, ny - 1, sizeof(float));
    delta_io_to_fb = (float **)alloc_matrix(0, nx, 0, ny, sizeof(float));
    delta_fb_to_io = (float **)alloc_matrix(0, nx, 0, ny, sizeof(float));
    delta_io_to_io =
        (float **)alloc_matrix(0, nx + 1, 0, ny + 1, sizeof(float));


    /*initialize all of the array locations to -1 */

    for(id_x = 0; id_x <= nx; id_x++)
        {
            for(id_y = 0; id_y <= ny; id_y++)
                {
                    delta_io_to_fb[id_x][id_y] = IMPOSSIBLE;
                }
        }
    for(id_x = 0; id_x <= nx - 1; id_x++)
        {
            for(id_y = 0; id_y <= ny - 1; id_y++)
                {
                    delta_fb_to_fb[id_x][id_y] = IMPOSSIBLE;
                }
        }
    for(id_x = 0; id_x <= nx; id_x++)
        {
            for(id_y = 0; id_y <= ny; id_y++)
                {
                    delta_fb_to_io[id_x][id_y] = IMPOSSIBLE;
                }
        }
    for(id_x = 0; id_x <= nx + 1; id_x++)
        {
            for(id_y = 0; id_y <= ny + 1; id_y++)
                {
                    delta_io_to_io[id_x][id_y] = IMPOSSIBLE;
                }
        }
}

/**************************************/
static void
free_delta_arrays(void)
{

    free_matrix(delta_io_to_fb, 0, nx, 0, sizeof(float));
    free_matrix(delta_fb_to_fb, 0, nx - 1, 0, sizeof(float));
    free_matrix(delta_fb_to_io, 0, nx, 0, sizeof(float));
    free_matrix(delta_io_to_io, 0, nx + 1, 0, sizeof(float));

}

/**************************************/
static void
generic_compute_matrix(float ***matrix_ptr,
                       t_type_ptr source_type,
                       t_type_ptr sink_type,
                       int source_x,
                       int source_y,
                       int start_x,
                       int end_x,
                       int start_y,
                       int end_y,
                       struct s_router_opts router_opts,
                       struct s_det_routing_arch det_routing_arch,
                       t_segment_inf * segment_inf,
                       t_timing_inf timing_inf)
{

    int delta_x, delta_y;
    int sink_x, sink_y;

    for(sink_x = start_x; sink_x <= end_x; sink_x++)
        {
            for(sink_y = start_y; sink_y <= end_y; sink_y++)
                {
                    delta_x = abs(sink_x - source_x);
                    delta_y = abs(sink_y - source_y);

                    if(delta_x == 0 && delta_y == 0)
                        continue;       /*do not compute distance from a block to itself     */
                    /*if a value is desired, pre-assign it somewhere else */

                    (*matrix_ptr)[delta_x][delta_y] =
                        assign_blocks_and_route_net(source_type, source_x,
                                                    source_y, sink_type,
                                                    sink_x, sink_y,
                                                    router_opts,
                                                    det_routing_arch,
                                                    segment_inf, timing_inf);
                }
        }
}

/**************************************/
static void
compute_delta_fb_to_fb(struct s_router_opts router_opts,
                       struct s_det_routing_arch det_routing_arch,
                       t_segment_inf * segment_inf,
                       t_timing_inf timing_inf,
                       int longest_length)
{

    /*this routine must compute delay values in a slightly different way than the */
    /*other compute routines. We cannot use a location close to the edge as the  */
    /*source location for the majority of the delay computations  because this   */
    /*would give gradually increasing delay values. To avoid this from happening */
    /*a clb that is at least longest_length away from an edge should be chosen   */
    /*as a source , if longest_length is more than 0.5 of the total size then    */
    /*choose a FB at the center as the source FB */

    int source_x, source_y, sink_x, sink_y;
    int start_x, start_y, end_x, end_y;
    int delta_x, delta_y;
    t_type_ptr source_type, sink_type;

    source_type = FILL_TYPE;
    sink_type = FILL_TYPE;

    if(longest_length < 0.5 * (nx))
        {
            start_x = longest_length;
        }
    else
        {
            start_x = (int)(0.5 * nx);
        }
    end_x = nx;
    source_x = start_x;

    if(longest_length < 0.5 * (ny))
        {
            start_y = longest_length;
        }
    else
        {
            start_y = (int)(0.5 * ny);
        }
    end_y = ny;
    source_y = start_y;


    /*don't put the sink all the way to the corner, until it is necessary */
    for(sink_x = start_x; sink_x <= end_x - 1; sink_x++)
        {
            for(sink_y = start_y; sink_y <= end_y - 1; sink_y++)
                {
                    delta_x = abs(sink_x - source_x);
                    delta_y = abs(sink_y - source_y);

                    if(delta_x == 0 && delta_y == 0)
                        {
                            delta_fb_to_fb[delta_x][delta_y] = 0.0;
                            continue;
                        }
                    delta_fb_to_fb[delta_x][delta_y] =
                        assign_blocks_and_route_net(source_type, source_x,
                                                    source_y, sink_type,
                                                    sink_x, sink_y,
                                                    router_opts,
                                                    det_routing_arch,
                                                    segment_inf, timing_inf);
                }

        }


    sink_x = end_x - 1;
    sink_y = end_y - 1;

    for(source_x = start_x - 1; source_x >= 1; source_x--)
        {
            for(source_y = start_y; source_y <= end_y - 1; source_y++)
                {
                    delta_x = abs(sink_x - source_x);
                    delta_y = abs(sink_y - source_y);

                    delta_fb_to_fb[delta_x][delta_y] =
                        assign_blocks_and_route_net(source_type, source_x,
                                                    source_y, sink_type,
                                                    sink_x, sink_y,
                                                    router_opts,
                                                    det_routing_arch,
                                                    segment_inf, timing_inf);
                }
        }

    for(source_x = 1; source_x <= end_x - 1; source_x++)
        {
            for(source_y = 1; source_y < start_y; source_y++)
                {
                    delta_x = abs(sink_x - source_x);
                    delta_y = abs(sink_y - source_y);

                    delta_fb_to_fb[delta_x][delta_y] =
                        assign_blocks_and_route_net(source_type, source_x,
                                                    source_y, sink_type,
                                                    sink_x, sink_y,
                                                    router_opts,
                                                    det_routing_arch,
                                                    segment_inf, timing_inf);
                }
        }


    /*now move sink into the top right corner */
    sink_x = end_x;
    sink_y = end_y;
    source_x = 1;
    for(source_y = 1; source_y <= end_y; source_y++)
        {
            delta_x = abs(sink_x - source_x);
            delta_y = abs(sink_y - source_y);

            delta_fb_to_fb[delta_x][delta_y] =
                assign_blocks_and_route_net(source_type, source_x, source_y,
                                            sink_type, sink_x, sink_y,
                                            router_opts, det_routing_arch,
                                            segment_inf, timing_inf);

        }

    sink_x = end_x;
    sink_y = end_y;
    source_y = 1;
    for(source_x = 1; source_x <= end_x; source_x++)
        {
            delta_x = abs(sink_x - source_x);
            delta_y = abs(sink_y - source_y);

            delta_fb_to_fb[delta_x][delta_y] =
                assign_blocks_and_route_net(source_type, source_x, source_y,
                                            sink_type, sink_x, sink_y,
                                            router_opts, det_routing_arch,
                                            segment_inf, timing_inf);
        }
}

/**************************************/
static void
compute_delta_io_to_fb(struct s_router_opts router_opts,
                       struct s_det_routing_arch det_routing_arch,
                       t_segment_inf * segment_inf,
                       t_timing_inf timing_inf)
{
    int source_x, source_y;
    int start_x, start_y, end_x, end_y;
    t_type_ptr source_type, sink_type;

    source_type = IO_TYPE;
    sink_type = FILL_TYPE;

    delta_io_to_fb[0][0] = IMPOSSIBLE;
    delta_io_to_fb[nx][ny] = IMPOSSIBLE;

    source_x = 0;
    source_y = 1;

    start_x = 1;
    end_x = nx;
    start_y = 1;
    end_y = ny;
    generic_compute_matrix(&delta_io_to_fb, source_type, sink_type,
                           source_x, source_y, start_x, end_x, start_y,
                           end_y, router_opts, det_routing_arch,
                           segment_inf, timing_inf);

    source_x = 1;
    source_y = 0;

    start_x = 1;
    end_x = 1;
    start_y = 1;
    end_y = ny;
    generic_compute_matrix(&delta_io_to_fb, source_type, sink_type,
                           source_x, source_y, start_x, end_x, start_y,
                           end_y, router_opts, det_routing_arch,
                           segment_inf, timing_inf);

    start_x = 1;
    end_x = nx;
    start_y = ny;
    end_y = ny;
    generic_compute_matrix(&delta_io_to_fb, source_type, sink_type,
                           source_x, source_y, start_x, end_x, start_y,
                           end_y, router_opts, det_routing_arch,
                           segment_inf, timing_inf);
}

/**************************************/
static void
compute_delta_fb_to_io(struct s_router_opts router_opts,
                       struct s_det_routing_arch det_routing_arch,
                       t_segment_inf * segment_inf,
                       t_timing_inf timing_inf)
{
    int source_x, source_y, sink_x, sink_y;
    int delta_x, delta_y;
    t_type_ptr source_type, sink_type;

    source_type = FILL_TYPE;
    sink_type = IO_TYPE;

    delta_fb_to_io[0][0] = IMPOSSIBLE;
    delta_fb_to_io[nx][ny] = IMPOSSIBLE;

    sink_x = 0;
    sink_y = 1;
    for(source_x = 1; source_x <= nx; source_x++)
        {
            for(source_y = 1; source_y <= ny; source_y++)
                {
                    delta_x = abs(source_x - sink_x);
                    delta_y = abs(source_y - sink_y);

                    delta_fb_to_io[delta_x][delta_y] =
                        assign_blocks_and_route_net(source_type, source_x,
                                                    source_y, sink_type,
                                                    sink_x, sink_y,
                                                    router_opts,
                                                    det_routing_arch,
                                                    segment_inf, timing_inf);
                }
        }

    sink_x = 1;
    sink_y = 0;
    source_x = 1;
    delta_x = abs(source_x - sink_x);
    for(source_y = 1; source_y <= ny; source_y++)
        {
            delta_y = abs(source_y - sink_y);
            delta_fb_to_io[delta_x][delta_y] =
                assign_blocks_and_route_net(source_type, source_x, source_y,
                                            sink_type, sink_x, sink_y,
                                            router_opts, det_routing_arch,
                                            segment_inf, timing_inf);
        }

    sink_x = 1;
    sink_y = 0;
    source_y = ny;
    delta_y = abs(source_y - sink_y);
    for(source_x = 2; source_x <= nx; source_x++)
        {
            delta_x = abs(source_x - sink_x);
            delta_fb_to_io[delta_x][delta_y] =
                assign_blocks_and_route_net(source_type, source_x, source_y,
                                            sink_type, sink_x, sink_y,
                                            router_opts, det_routing_arch,
                                            segment_inf, timing_inf);
        }
}

/**************************************/
static void
compute_delta_io_to_io(struct s_router_opts router_opts,
                       struct s_det_routing_arch det_routing_arch,
                       t_segment_inf * segment_inf,
                       t_timing_inf timing_inf)
{
    int source_x, source_y, sink_x, sink_y;
    int delta_x, delta_y;
    t_type_ptr source_type, sink_type;

    source_type = IO_TYPE;
    sink_type = IO_TYPE;

    delta_io_to_io[0][0] = 0;   /*delay to itself is 0 (this can happen) */
    delta_io_to_io[nx + 1][ny + 1] = IMPOSSIBLE;
    delta_io_to_io[0][ny] = IMPOSSIBLE;
    delta_io_to_io[nx][0] = IMPOSSIBLE;
    delta_io_to_io[nx][ny + 1] = IMPOSSIBLE;
    delta_io_to_io[nx + 1][ny] = IMPOSSIBLE;


    source_x = 0;
    source_y = 1;
    sink_x = 0;
    delta_x = abs(sink_x - source_x);


    for(sink_y = 2; sink_y <= ny; sink_y++)
        {
            delta_y = abs(sink_y - source_y);
            delta_io_to_io[delta_x][delta_y] =
                assign_blocks_and_route_net(source_type, source_x, source_y,
                                            sink_type, sink_x, sink_y,
                                            router_opts, det_routing_arch,
                                            segment_inf, timing_inf);

        }

    source_x = 0;
    source_y = 1;
    sink_x = nx + 1;
    delta_x = abs(sink_x - source_x);

    for(sink_y = 1; sink_y <= ny; sink_y++)
        {
            delta_y = abs(sink_y - source_y);
            delta_io_to_io[delta_x][delta_y] =
                assign_blocks_and_route_net(source_type, source_x, source_y,
                                            sink_type, sink_x, sink_y,
                                            router_opts, det_routing_arch,
                                            segment_inf, timing_inf);

        }


    source_x = 1;
    source_y = 0;
    sink_y = 0;
    delta_y = abs(sink_y - source_y);

    for(sink_x = 2; sink_x <= nx; sink_x++)
        {
            delta_x = abs(sink_x - source_x);
            delta_io_to_io[delta_x][delta_y] =
                assign_blocks_and_route_net(source_type, source_x, source_y,
                                            sink_type, sink_x, sink_y,
                                            router_opts, det_routing_arch,
                                            segment_inf, timing_inf);

        }

    source_x = 1;
    source_y = 0;
    sink_y = ny + 1;
    delta_y = abs(sink_y - source_y);

    for(sink_x = 1; sink_x <= nx; sink_x++)
        {
            delta_x = abs(sink_x - source_x);
            delta_io_to_io[delta_x][delta_y] =
                assign_blocks_and_route_net(source_type, source_x, source_y,
                                            sink_type, sink_x, sink_y,
                                            router_opts, det_routing_arch,
                                            segment_inf, timing_inf);

        }

    source_x = 0;
    sink_y = ny + 1;
    for(source_y = 1; source_y <= ny; source_y++)
        {
            for(sink_x = 1; sink_x <= nx; sink_x++)
                {
                    delta_y = abs(source_y - sink_y);
                    delta_x = abs(source_x - sink_x);
                    delta_io_to_io[delta_x][delta_y] =
                        assign_blocks_and_route_net(source_type, source_x,
                                                    source_y, sink_type,
                                                    sink_x, sink_y,
                                                    router_opts,
                                                    det_routing_arch,
                                                    segment_inf, timing_inf);

                }
        }
}

/**************************************/
#ifdef PRINT_ARRAYS
static void
print_array(float **array_to_print,
            int x1,
            int x2,
            int y1,
            int y2)
{


    int idx_x, idx_y;

    fprintf(lookup_dump, "\nPrinting Array \n\n");

    for(idx_y = y2; idx_y >= y1; idx_y--)
        {
            for(idx_x = x1; idx_x <= x2; idx_x++)
                {
                    fprintf(lookup_dump, " %9.2e",
                            array_to_print[idx_x][idx_y]);
                }
            fprintf(lookup_dump, "\n");
        }
    fprintf(lookup_dump, "\n\n");
}
#endif
/**************************************/
static void
compute_delta_arrays(struct s_router_opts router_opts,
                     struct s_det_routing_arch det_routing_arch,
                     t_segment_inf * segment_inf,
                     t_timing_inf timing_inf,
                     int longest_length)
{

    printf
        ("Computing delta_io_to_io lookup matrix, may take a few seconds, please wait...\n");
    compute_delta_io_to_io(router_opts, det_routing_arch, segment_inf,
                           timing_inf);
    printf
        ("Computing delta_io_to_fb lookup matrix, may take a few seconds, please wait...\n");
    compute_delta_io_to_fb(router_opts, det_routing_arch, segment_inf,
                           timing_inf);
    printf
        ("Computing delta_fb_to_io lookup matrix, may take a few seconds, please wait...\n");
    compute_delta_fb_to_io(router_opts, det_routing_arch, segment_inf,
                           timing_inf);
    printf
        ("Computing delta_fb_to_fb lookup matrix, may take a few seconds, please wait...\n");
    compute_delta_fb_to_fb(router_opts, det_routing_arch, segment_inf,
                           timing_inf, longest_length);

#ifdef PRINT_ARRAYS
    lookup_dump = my_fopen(DUMPFILE, "w");
    fprintf(lookup_dump, "\n\nprinting delta_fb_to_fb\n");
    print_array(delta_fb_to_fb, 0, nx - 1, 0, ny - 1);
    fprintf(lookup_dump, "\n\nprinting delta_io_to_fb\n");
    print_array(delta_io_to_fb, 0, nx, 0, ny);
    fprintf(lookup_dump, "\n\nprinting delta_fb_to_io\n");
    print_array(delta_fb_to_io, 0, nx, 0, ny);
    fprintf(lookup_dump, "\n\nprinting delta_io_to_io\n");
    print_array(delta_io_to_io, 0, nx + 1, 0, ny + 1);
    fclose(lookup_dump);
#endif

}

/******* Globally Accessable Functions **********/

/**************************************/
void
compute_delay_lookup_tables(struct s_router_opts router_opts,
                            struct s_det_routing_arch det_routing_arch,
                            t_segment_inf * segment_inf,
                            t_timing_inf timing_inf,
                            t_chan_width_dist chan_width_dist,
                            t_subblock_data subblock_data)
{

    static struct s_net *original_net;  /*this will be used as a pointer to remember what */

    /*the "real" nets in the circuit are. This is    */
    /*required because we are using the net structure */
    /*in these routines to find delays between blocks */
    static struct s_block *original_block;      /*same def as original_nets, but for block  */

    static int original_num_nets;
    static int original_num_blocks;
    static int longest_length;

    load_simplified_device();

    alloc_and_assign_internal_structures(&original_net,
                                         &original_block,
                                         &original_num_nets,
                                         &original_num_blocks);
    setup_chan_width(router_opts, chan_width_dist);

    alloc_routing_structs(router_opts, det_routing_arch, segment_inf,
                          timing_inf, subblock_data);

    longest_length =
        get_longest_segment_length(det_routing_arch, segment_inf);


    /*now setup and compute the actual arrays */
    alloc_delta_arrays();
    compute_delta_arrays(router_opts, det_routing_arch, segment_inf,
                         timing_inf, longest_length);

    /*free all data structures that are no longer needed */
    free_routing_structs(router_opts, det_routing_arch, segment_inf,
                         timing_inf);

    restore_original_device();

    free_and_reset_internal_structures(original_net, original_block,
                                       original_num_nets,
                                       original_num_blocks);
}

/**************************************/
void
free_place_lookup_structs(void)
{

    free_delta_arrays();

}

---