From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Fri, 24 Jan 2020 12:15:21 +0000 (+0000)
Subject: add partitioned eq module
X-Git-Tag: ls180-24jan2020~345
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=77d04dbfc63319aa19d8df2902bd63cf02b19bce;p=ieee754fpu.git

add partitioned eq module
---

diff --git a/src/ieee754/part_cmp/equal.py b/src/ieee754/part_cmp/equal.py
new file mode 100644
index 00000000..2fa1f0d2
--- /dev/null
+++ b/src/ieee754/part_cmp/equal.py
@@ -0,0 +1,44 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+# See Notices.txt for copyright information
+
+"""
+Copyright (C) 2020 Luke Kenneth Casson Leighton <lkcl@lkcl.net>
+
+dynamically-partitionable "comparison" class, directly equivalent
+to Signal.__eq__ except SIMD-partitionable
+"""
+
+from nmigen import Signal, Module, Elaboratable, Cat, C, Mux, Repl
+from nmigen.cli import main
+
+from ieee754.part_mul_add.partpoints import PartitionPoints
+
+class PartitionedEq(Elaboratable):
+
+    def __init__(self, width, partition_points):
+        """Create a ``PartitionedEq`` operator
+        """
+        self.width = width
+        self.a = Signal(width, reset_less=True)
+        self.b = Signal(width, reset_less=True)
+        self.partition_points = PartitionPoints(partition_points)
+        self.mwidth = len(self.partition_points)
+        self.output = Signal(mwidth, reset_less=True)
+        if not self.partition_points.fits_in_width(width):
+            raise ValueError("partition_points doesn't fit in width")
+
+    def elaborate(self, platform):
+        m = Module()
+
+        # make a series of "eqs", splitting a and b into partition chunks
+        chunks = self.width // self.mwidth
+        eqs = Signal(self.mwidth, reset_less=True)
+        eql = []
+        keys = self.partition_points.keys()
+        for i in range(len(keys)-1):
+            start, end = keys[i], keys[i+1]
+            eql.append(self.a[start:end] == self.b[start:end])
+        m.d.comb += eqs.eq(Cat(*l))
+
+        # now, based on the partition points, create the (multi-)boolean result
+        m.d.comb += self.out.eq(eqs) # TODO: respect partition points