# Copyright (c) 2010 Advanced Micro Devices, Inc.
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# Authors: Brad Beckmann

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

class Mesh(Topology):
    description='Mesh'

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

def makeTopology(nodes, options, IntLink, ExtLink, Router):

    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)

    # Create the routers in the mesh
    routers = [Router(router_id=i) for i in range(num_routers)]

    # link counter to set unique link ids
    link_count = 0

    # 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(link_id=link_count, ext_node=n,
                                 int_node=routers[router_id]))
        link_count += 1

    # 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(link_id=link_count, ext_node=node,
                                 int_node=routers[0]))
        link_count += 1

    # 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(link_id=link_count,
                                         node_a=routers[east_id],
                                         node_b=routers[west_id],
                                         weight=1))
                link_count += 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(link_id=link_count,
                                         node_a=routers[north_id],
                                         node_b=routers[south_id],
                                         weight=2))
                link_count += 1
    return Mesh(ext_links=ext_links,
                int_links=int_links,
                routers=routers)
