src/nmutil/mask.py

   1 # SPDX-License-Identifier: LGPL-3-or-later
   2 """
   3     This work is funded through NLnet under Grant 2019-02-012
   4
   5     License: LGPLv3+
   6
   7
   8 """
   9
  10 from nmigen import Module, Signal, Elaboratable
  11 from nmigen.utils import log2_int
  12
  13
  14 def masked(m_out, m_in, mask):
  15     return (m_out & ~mask) | (m_in & mask)
  16
  17
  18 class Mask(Elaboratable):
  19     def __init__(self, sz):
  20         self.sz = sz
  21         self.shift = Signal(sz.bit_length()+1)
  22         self.mask = Signal(sz)
  23
  24     def elaborate(self, platform):
  25         m = Module()
  26
  27         for i in range(self.sz):
  28             with m.If(i < self.shift):
  29                 m.d.comb += self.mask[i].eq(1)
  30
  31         return m