src/nmutil/mask.py

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