import unittest
import random

from migen import *

from litedram.common import *
from litedram.frontend.axi import *

from litex.gen.sim import *


class Burst:
    def __init__(self, addr, type=BURST_FIXED, len=0, size=0):
        self.addr = addr
        self.type = type
        self.len = len
        self.size = size

    def to_beats(self):
        r = []
        for i in range(self.len + 1):
            if self.type == BURST_INCR:
                offset = i*2**(self.size)
                r += [Beat(self.addr + offset)]
            elif self.type == BURST_WRAP:
                offset = (i*2**(self.size))%((2**self.size)*(self.len + 1))
                r += [Beat(self.addr + offset)]
            else:
                r += [Beat(self.addr)]
        return r


class Beat:
    def __init__(self, addr):
        self.addr = addr


class TestAXI(unittest.TestCase):
    def test_burst2beat(self):
        def bursts_generator(ax, bursts, valid_rand=50):
            prng = random.Random(42)
            for burst in bursts:
                yield ax.valid.eq(1)
                yield ax.addr.eq(burst.addr)
                yield ax.burst.eq(burst.type)
                yield ax.len.eq(burst.len)
                yield ax.size.eq(burst.size)
                while (yield ax.ready) == 0:
                    yield
                yield ax.valid.eq(0)
                while prng.randrange(100) < valid_rand:
                    yield
                yield

        @passive
        def beats_checker(ax, beats, ready_rand=50):
            self.errors = 0
            yield ax.ready.eq(0)
            prng = random.Random(42)
            for beat in beats:
                while ((yield ax.valid) and (yield ax.ready)) == 0:
                    if prng.randrange(100) > ready_rand:
                        yield ax.ready.eq(1)
                    else:
                        yield ax.ready.eq(0)
                    yield
                ax_addr = (yield ax.addr)
                if ax_addr != beat.addr:
                    self.errors += 1
                yield

        # dut
        ax_burst = stream.Endpoint(ax_description(32, 32))
        ax_beat = stream.Endpoint(ax_description(32, 32))
        dut =  AXIBurst2Beat(ax_burst, ax_beat)

        # generate dut input (bursts)
        prng = random.Random(42)
        bursts = []
        for i in range(32):
            bursts.append(Burst(prng.randrange(2**32), BURST_FIXED, prng.randrange(255), log2_int(32//8)))
            bursts.append(Burst(prng.randrange(2**32), BURST_INCR, prng.randrange(255), log2_int(32//8)))
        bursts.append(Burst(4, BURST_WRAP, 4-1, log2_int(2)))

        # generate expected dut output (beats for reference)
        beats = []
        for burst in bursts:
            beats += burst.to_beats()

        # simulation
        generators = [
            bursts_generator(ax_burst, bursts),
            beats_checker(ax_beat, beats)
        ]
        run_simulation(dut, generators)
        self.assertEqual(self.errors, 0)