# Copyright (c) 2010 Advanced Micro Devices, Inc.
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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# Authors: Brad Beckmann

from m5.params import *
from m5.objects import *

#
# Makes a generic mesh assuming an equal number of cache and directory cntrls
#

def makeTopology(nodes, options):

    num_routers = options.num_cpus
    num_rows = options.mesh_rows
    
    #
    # There must be an evenly divisible number of cntrls to routers
    # Also, obviously the number or rows must be <= the number of routers
    #
    cntrls_per_router, remainder = divmod(len(nodes), num_routers)
    assert(num_rows <= num_routers)
    num_columns = int(num_routers / num_rows)
    assert(num_columns * num_rows == num_routers)

    #
    # Add all but the remainder nodes to the list of nodes to be uniformly
    # distributed across the network.
    #
    network_nodes = []
    remainder_nodes = []
    for node_index in xrange(len(nodes)):
        if node_index < (len(nodes) - remainder):
            network_nodes.append(nodes[node_index])
        else:
            remainder_nodes.append(nodes[node_index])

    #
    # Connect each node to the appropriate router
    #
    ext_links = []
    for (i, n) in enumerate(network_nodes):
        cntrl_level, router_id = divmod(i, num_routers)
        assert(cntrl_level < cntrls_per_router)
        ext_links.append(ExtLink(ext_node=n, int_node=router_id))

    #
    # Connect the remainding nodes to router 0.  These should only be DMA nodes.
    #
    for (i, node) in enumerate(remainder_nodes):
        assert(node.type == 'DMA_Controller')
        assert(i < remainder)
        ext_links.append(ExtLink(ext_node=node, int_node=0))
    
    #
    # Create the mesh links.  First row (east-west) links then column
    # (north-south) links
    #
    int_links = []
    for row in xrange(num_rows):
        for col in xrange(num_columns):
            if (col + 1 < num_columns):
                east_id = col + (row * num_columns)
                west_id = (col + 1) + (row * num_columns)
                int_links.append(IntLink(node_a=east_id,
                                         node_b=west_id,
                                         weight=1))
    for col in xrange(num_columns):
        for row in xrange(num_rows):
            if (row + 1 < num_rows):
                north_id = col + (row * num_columns)
                south_id = col + ((row + 1) * num_columns)
                int_links.append(IntLink(node_a=north_id,
                                         node_b=south_id,
                                         weight=2))

    return Topology(ext_links=ext_links,
                    int_links=int_links,
                    num_int_nodes=num_routers)