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# Authors: Andreas Sandberg
#          Andreas Hansson

from __future__ import print_function
from __future__ import absolute_import

import m5.objects
from common import ObjectList
from . import HMC

def create_mem_ctrl(cls, r, i, nbr_mem_ctrls, intlv_bits, intlv_size):
    """
    Helper function for creating a single memoy controller from the given
    options.  This function is invoked multiple times in config_mem function
    to create an array of controllers.
    """

    import math
    intlv_low_bit = int(math.log(intlv_size, 2))

    # Use basic hashing for the channel selection, and preferably use
    # the lower tag bits from the last level cache. As we do not know
    # the details of the caches here, make an educated guess. 4 MByte
    # 4-way associative with 64 byte cache lines is 6 offset bits and
    # 14 index bits.
    xor_low_bit = 20

    # Create an instance so we can figure out the address
    # mapping and row-buffer size
    ctrl = cls()

    # Only do this for DRAMs
    if issubclass(cls, m5.objects.DRAMCtrl):
        # If the channel bits are appearing after the column
        # bits, we need to add the appropriate number of bits
        # for the row buffer size
        if ctrl.addr_mapping.value == 'RoRaBaChCo':
            # This computation only really needs to happen
            # once, but as we rely on having an instance we
            # end up having to repeat it for each and every
            # one
            rowbuffer_size = ctrl.device_rowbuffer_size.value * \
                ctrl.devices_per_rank.value

            intlv_low_bit = int(math.log(rowbuffer_size, 2))

    # We got all we need to configure the appropriate address
    # range
    ctrl.range = m5.objects.AddrRange(r.start, size = r.size(),
                                      intlvHighBit = \
                                          intlv_low_bit + intlv_bits - 1,
                                      xorHighBit = \
                                          xor_low_bit + intlv_bits - 1,
                                      intlvBits = intlv_bits,
                                      intlvMatch = i)
    return ctrl

def config_mem(options, system):
    """
    Create the memory controllers based on the options and attach them.

    If requested, we make a multi-channel configuration of the
    selected memory controller class by creating multiple instances of
    the specific class. The individual controllers have their
    parameters set such that the address range is interleaved between
    them.
    """

    # Mandatory options
    opt_mem_type = options.mem_type
    opt_mem_channels = options.mem_channels

    # Optional options
    opt_tlm_memory = getattr(options, "tlm_memory", None)
    opt_external_memory_system = getattr(options, "external_memory_system",
                                         None)
    opt_elastic_trace_en = getattr(options, "elastic_trace_en", False)
    opt_mem_ranks = getattr(options, "mem_ranks", None)
    opt_dram_powerdown = getattr(options, "enable_dram_powerdown", None)

    if opt_mem_type == "HMC_2500_1x32":
        HMChost = HMC.config_hmc_host_ctrl(options, system)
        HMC.config_hmc_dev(options, system, HMChost.hmc_host)
        subsystem = system.hmc_dev
        xbar = system.hmc_dev.xbar
    else:
        subsystem = system
        xbar = system.membus

    if opt_tlm_memory:
        system.external_memory = m5.objects.ExternalSlave(
            port_type="tlm_slave",
            port_data=opt_tlm_memory,
            port=system.membus.master,
            addr_ranges=system.mem_ranges)
        system.kernel_addr_check = False
        return

    if opt_external_memory_system:
        subsystem.external_memory = m5.objects.ExternalSlave(
            port_type=opt_external_memory_system,
            port_data="init_mem0", port=xbar.master,
            addr_ranges=system.mem_ranges)
        subsystem.kernel_addr_check = False
        return

    nbr_mem_ctrls = opt_mem_channels
    import math
    from m5.util import fatal
    intlv_bits = int(math.log(nbr_mem_ctrls, 2))
    if 2 ** intlv_bits != nbr_mem_ctrls:
        fatal("Number of memory channels must be a power of 2")

    cls = ObjectList.mem_list.get(opt_mem_type)
    mem_ctrls = []

    if opt_elastic_trace_en and not issubclass(cls, m5.objects.SimpleMemory):
        fatal("When elastic trace is enabled, configure mem-type as "
                "simple-mem.")

    # The default behaviour is to interleave memory channels on 128
    # byte granularity, or cache line granularity if larger than 128
    # byte. This value is based on the locality seen across a large
    # range of workloads.
    intlv_size = max(128, system.cache_line_size.value)

    # For every range (most systems will only have one), create an
    # array of controllers and set their parameters to match their
    # address mapping in the case of a DRAM
    for r in system.mem_ranges:
        for i in range(nbr_mem_ctrls):
            mem_ctrl = create_mem_ctrl(cls, r, i, nbr_mem_ctrls, intlv_bits,
                                       intlv_size)
            # Set the number of ranks based on the command-line
            # options if it was explicitly set
            if issubclass(cls, m5.objects.DRAMCtrl) and opt_mem_ranks:
                mem_ctrl.ranks_per_channel = opt_mem_ranks

            # Enable low-power DRAM states if option is set
            if issubclass(cls, m5.objects.DRAMCtrl):
                mem_ctrl.enable_dram_powerdown = opt_dram_powerdown

            if opt_elastic_trace_en:
                mem_ctrl.latency = '1ns'
                print("For elastic trace, over-riding Simple Memory "
                    "latency to 1ns.")

            mem_ctrls.append(mem_ctrl)

    subsystem.mem_ctrls = mem_ctrls

    # Connect the controllers to the membus
    for i in range(len(subsystem.mem_ctrls)):
        if opt_mem_type == "HMC_2500_1x32":
            subsystem.mem_ctrls[i].port = xbar[i/4].master
            # Set memory device size. There is an independent controller for
            # each vault. All vaults are same size.
            subsystem.mem_ctrls[i].device_size = options.hmc_dev_vault_size
        else:
            subsystem.mem_ctrls[i].port = xbar.master