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 "route_export.h"
#include <assert.h>
#include "read_xml_arch_file.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_clb;
float **delta_clb_to_clb;
float **delta_clb_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 *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, INP t_direct_inf *directs, 
        INP int num_directs);

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_clb_to_clb(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_clb(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_clb_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;

    clb_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");
        clb_net[i].name = (char *) my_malloc((len + 1) * sizeof(char));
        clb_net[i].is_global = FALSE;
        strcpy(clb_net[NET_USED].name, "TEMP_NET");

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

        clb_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 = std::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 = (int*)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 = clb_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));

    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(clb_net[i].name);
        free(clb_net[i].node_block);
        free(clb_net[i].node_block_pin);
    }
    free(clb_net);
    clb_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));

}

/**************************************/
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_clb;

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

    if (router_opts.fixed_channel_width == NO_FIXED_CHANNEL_WIDTH)
        width_fac = 4 * max_pins_per_clb; /*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, INP t_direct_inf *directs, 
        INP int num_directs) {

    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();

    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,
            NULL, 0, TRUE, /* do not send in direct connections because we care about general placement timing instead of special pin placement timing */
            &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) {
    int i;
    free_rr_graph();

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

    free_timing_driven_route_structs(pin_criticality, sink_order,
            rt_node_of_sink);
    
    if (clb_opins_used_locally != NULL) {
        for (i = 0; i < num_blocks; i++) {
            free_ivec_vector(clb_opins_used_locally[i], 0,
                    block[i].type->num_class - 1);
        }
        free(clb_opins_used_locally);
        clb_opins_used_locally = NULL;
    }
}

/**************************************/
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;

    clb_net[NET_USED].node_block_pin[NET_USED_SOURCE_BLOCK] = get_first_pin(
            DRIVER, block[SOURCE_BLOCK].type);
    clb_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 */

    float pres_fac, 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);

    pres_fac = 0; /* ignore congestion */

    /* Route this net with a dummy criticality of 0 by calling 
    timing_driven_route_net with slacks set to NULL. */
    timing_driven_route_net(NET_USED, pres_fac,
            router_opts.max_criticality, router_opts.criticality_exp,
            router_opts.astar_fac, router_opts.bend_cost, 
            pin_criticality, sink_order, rt_node_of_sink, 
            net_delay[NET_USED], NULL);

    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_clb_to_clb = (float **) alloc_matrix(0, nx - 1, 0, ny - 1,
            sizeof(float));
    delta_io_to_clb = (float **) alloc_matrix(0, nx, 0, ny, sizeof(float));
    delta_clb_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_clb[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_clb_to_clb[id_x][id_y] = IMPOSSIBLE;
        }
    }
    for (id_x = 0; id_x <= nx; id_x++) {
        for (id_y = 0; id_y <= ny; id_y++) {
            delta_clb_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_clb, 0, nx, 0, sizeof(float));
    free_matrix(delta_clb_to_clb, 0, nx - 1, 0, sizeof(float));
    free_matrix(delta_clb_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_clb_to_clb(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 CLB at the center as the source CLB */

    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_clb_to_clb[delta_x][delta_y] = 0.0;
                continue;
            }
            delta_clb_to_clb[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_clb_to_clb[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_clb_to_clb[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_clb_to_clb[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_clb_to_clb[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_clb(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_clb[0][0] = IMPOSSIBLE;
    delta_io_to_clb[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_clb, 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_clb, 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_clb, 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_clb_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_clb_to_io[0][0] = IMPOSSIBLE;
    delta_clb_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_clb_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_clb_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_clb_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) {

    vpr_printf(TIO_MESSAGE_INFO, "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);
    vpr_printf(TIO_MESSAGE_INFO, "Computing delta_io_to_clb lookup matrix, may take a few seconds, please wait...\n");
    compute_delta_io_to_clb(router_opts, det_routing_arch, segment_inf, timing_inf);
    vpr_printf(TIO_MESSAGE_INFO, "Computing delta_clb_to_io lookup matrix, may take a few seconds, please wait...\n");
    compute_delta_clb_to_io(router_opts, det_routing_arch, segment_inf, timing_inf);
    vpr_printf(TIO_MESSAGE_INFO, "Computing delta_clb_to_clb lookup matrix, may take a few seconds, please wait...\n");
    compute_delta_clb_to_clb(router_opts, det_routing_arch, segment_inf, timing_inf, longest_length);

#ifdef PRINT_ARRAYS
    lookup_dump = my_fopen(DUMPFILE, "w", 0);
    fprintf(lookup_dump, "\n\nprinting delta_clb_to_clb\n");
    print_array(delta_clb_to_clb, 0, nx - 1, 0, ny - 1);
    fprintf(lookup_dump, "\n\nprinting delta_io_to_clb\n");
    print_array(delta_io_to_clb, 0, nx, 0, ny);
    fprintf(lookup_dump, "\n\nprinting delta_clb_to_io\n");
    print_array(delta_clb_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, INP t_direct_inf *directs, 
        INP int num_directs) {

    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, directs, num_directs);

    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();

}