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"""
The module defines PqosCatL2 which can be used to read or write L2 CAT
configuration.
"""

from __future__ import absolute_import, division, print_function
import ctypes

from pqos.capability import PqosCap
from pqos.common import pqos_handle_error, COSBase
from pqos.native_struct import CPqosL2Ca
from pqos.pqos import Pqos

class PqosCatL2(object):
    "PQoS L2 Cache Allocation Technology"

    class COS(COSBase):  # pylint: disable=too-few-public-methods
        "L2 class of service configuration"

    def __init__(self):
        self.pqos = Pqos()

    def set(self, l2id, coses):
        """
        Sets class of service on a specified l2id.

        Parameters:
            l2id: L2 cache identifier
            coses: a list of PqosCatL2.COS objects, class of service
                   configuration
        """

        pqos_l2_cas = [CPqosL2Ca.from_cos(cos) for cos in coses]
        pqos_l2_ca_arr = (CPqosL2Ca * len(pqos_l2_cas))(*pqos_l2_cas)
        ret = self.pqos.lib.pqos_l2ca_set(l2id, len(pqos_l2_cas),
                                          pqos_l2_ca_arr)
        pqos_handle_error('pqos_l2ca_set', ret)

    def get(self, l2id):
        """
        Reads classes of service from a L2 ID.

        Parameters:
            l2id: L2 cache identifier
        """

        cap = PqosCap()
        cos_num = cap.get_l2ca_cos_num()

        l2cas = (CPqosL2Ca * cos_num)()
        num_ca = ctypes.c_uint(0)
        num_ca_ref = ctypes.byref(num_ca)
        ret = self.pqos.lib.pqos_l2ca_get(l2id, cos_num, num_ca_ref, l2cas)
        pqos_handle_error('pqos_l2ca_get', ret)

        coses = [l2ca.to_cos(self.COS) for l2ca in l2cas[:num_ca.value]]
        return coses

    def get_min_cbm_bits(self):
        """Gets minimum number of bits which must be set in L2 way mask when
        updating a class of service."""

        min_cbm_bits = ctypes.c_uint(0)
        min_cbm_bits_ref = ctypes.byref(min_cbm_bits)
        ret = self.pqos.lib.pqos_l2ca_get_min_cbm_bits(min_cbm_bits_ref)
        pqos_handle_error('pqos_l2ca_get_min_cbm_bits', ret)
        return min_cbm_bits.value
