src/ieee754/part/partsig.py

   1 # SPDX-License-Identifier: LGPL-2.1-or-later
   2 # See Notices.txt for copyright information
   3
   4 """
   5 Copyright (C) 2020 Luke Kenneth Casson Leighton <lkcl@lkcl.net>
   6
   7 dynamic-partitionable class similar to Signal, which, when the partition
   8 is fully open will be identical to Signal.  when partitions are closed,
   9 the class turns into a SIMD variant of Signal.  *this is dynamic*.
  10
  11 the basic fundamental idea is: write code once, and if you want a SIMD
  12 version of it, use PartitionedSignal in place of Signal.  job done.
  13 this however requires the code to *not* be designed to use nmigen.If,
  14 nmigen.Case, or other constructs: only Mux and other logic.
  15
  16 http://bugs.libre-riscv.org/show_bug.cgi?id=132
  17 """
  18
  19 from ieee754.part_mul_add.adder import PartitionedAdder
  20 from ieee754.part_mul_add.partpoints import make_partition
  21 from nmigen import (Signal,
  22                     )
  23
  24 class PartitionedSignal:
  25     def __init__(self, mask, *args, **kwargs):
  26         self.sig = Signal(*args, **kwargs)
  27         width = self.sig.shape()[0] # get signal width
  28         self.partpoints = make_partition(mask, width) # create partition points
  29         self.modnames = {}
  30         for name in ['add']:
  31             self.modnames[name] = 0
  32
  33     def set_module(self, m):
  34         self.m = m
  35
  36     def get_modname(self, category):
  37         self.modnames[category] += 1
  38         return "%s%d" % (category, self.modnames[category])
  39
  40     def eq(self, val):
  41         return self.sig.eq(val)
  42
  43     def __xor__(self, other):
  44         if isinstance(other, PartitionedSignal):
  45             return self.sig ^ other.sig
  46         return self.sig ^ other
  47
  48     def __add__(self, other):
  49         shape = self.sig.shape()
  50         pa = PartitionedAdder(shape[0], self.partpoints)
  51         setattr(self.m.submodules, self.get_modname('add'), pa)
  52         comb = self.m.d.comb
  53         comb += pa.a.eq(self.sig)
  54         if isinstance(other, PartitionedSignal):
  55             comb += pa.b.eq(other.sig)
  56         else:
  57             comb += pa.b.eq(other)
  58         return pa.output