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 def masked(m_out, m_in, mask):
  13     return (m_out & ~mask) | (m_in & mask)
  14
  15
  16 class Mask(Elaboratable):
  17     def __init__(self, sz):
  18         self.sz = sz
  19         self.shift = Signal(log2_int(sz, False)+1)
  20         self.mask = Signal(sz)
  21
  22     def elaborate(self, platform):
  23         m = Module()
  24
  25         for i in range(self.sz):
  26             with m.If(self.shift > i):
  27                 m.d.comb += self.mask[i].eq(1)
  28
  29         return m
  30