litex/misoclib/video/dvisampler/charsync.py

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from migen.fhdl.std import *
from migen.genlib.cdc import MultiReg
from migen.genlib.misc import optree
from migen.bank.description import *
from misoclib.video.dvisampler.common import control_tokens
class CharSync(Module, AutoCSR):
def __init__(self, required_controls=8):
self.raw_data = Signal(10)
self.synced = Signal()
self.data = Signal(10)
self._r_char_synced = CSRStatus()
self._r_ctl_pos = CSRStatus(bits_for(9))
###
raw_data1 = Signal(10)
self.sync.pix += raw_data1.eq(self.raw_data)
raw = Signal(20)
self.comb += raw.eq(Cat(raw_data1, self.raw_data))
found_control = Signal()
control_position = Signal(max=10)
self.sync.pix += found_control.eq(0)
for i in range(10):
self.sync.pix += If(optree("|", [raw[i:i+10] == t for t in control_tokens]),
found_control.eq(1),
control_position.eq(i)
)
control_counter = Signal(max=required_controls)
previous_control_position = Signal(max=10)
word_sel = Signal(max=10)
self.sync.pix += [
If(found_control & (control_position == previous_control_position),
If(control_counter == (required_controls - 1),
control_counter.eq(0),
self.synced.eq(1),
word_sel.eq(control_position)
).Else(
control_counter.eq(control_counter + 1)
)
).Else(
control_counter.eq(0)
),
previous_control_position.eq(control_position)
]
self.specials += MultiReg(self.synced, self._r_char_synced.status)
self.specials += MultiReg(word_sel, self._r_ctl_pos.status)
self.sync.pix += self.data.eq(raw >> word_sel)