add PartitionedBool class (based on PartitionedXOR)

could very likely be combined but hey

diff --git a/src/ieee754/part_bits/bool.py b/src/ieee754/part_bits/bool.py
new file mode 100644 (file)
index 0000000..6c9e2cb
--- /dev/null
+++ b/src/ieee754/part_bits/bool.py
@@ -0,0 +1,137 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+# See Notices.txt for copyright information
+
+"""
+Copyright (C) 2020,2021 Luke Kenneth Casson Leighton <lkcl@lkcl.net>
+
+dynamically-partitionable "bool" class, directly equivalent
+to Signal.bool() except SIMD-partitionable
+
+See:
+
+* http://libre-riscv.org/3d_gpu/architecture/dynamic_simd/logicops
+* http://bugs.libre-riscv.org/show_bug.cgi?id=176
+"""
+
+from nmigen import Signal, Module, Elaboratable, Cat, C
+from nmigen.back.pysim import Simulator, Settle
+from nmigen.cli import rtlil
+from nmutil.ripple import RippleLSB
+
+from ieee754.part_mul_add.partpoints import PartitionPoints
+from ieee754.part_cmp.experiments.eq_combiner import EQCombiner
+
+
+class PartitionedBool(Elaboratable):
+
+    def __init__(self, width, partition_points):
+        """Create a ``PartitionedBool`` operator
+        """
+        self.width = width
+        self.a = Signal(width, reset_less=True)
+        self.partition_points = PartitionPoints(partition_points)
+        self.mwidth = len(self.partition_points)+1
+        self.output = Signal(self.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()
+        comb = m.d.comb
+        m.submodules.boolc = boolc = EQCombiner(self.mwidth)
+
+        # make a series of "bool", splitting a and b into partition chunks
+        bools = Signal(self.mwidth, reset_less=True)
+        booll = []
+        keys = list(self.partition_points.keys()) + [self.width]
+        start = 0
+        for i in range(len(keys)):
+            end = keys[i]
+            booll.append(self.a[start:end].bool())
+            start = end # for next time round loop
+        comb += bools.eq(Cat(*booll))
+
+        # put the partial results through the combiner
+        comb += boolc.gates.eq(self.partition_points.as_sig())
+        comb += boolc.neqs.eq(bools)
+
+        m.submodules.ripple = ripple = RippleLSB(self.mwidth)
+        comb += ripple.results_in.eq(boolc.outputs)
+        comb += ripple.gates.eq(self.partition_points.as_sig())
+        comb += self.output.eq(~ripple.output)
+
+        return m
+
+    def ports(self):
+        return [self.a, self.output]
+
+
+if __name__ == "__main__":
+
+    from ieee754.part_mul_add.partpoints import make_partition
+    m = Module()
+    mask = Signal(4)
+    m.submodules.mbool = mbool = PartitionedBool(16, make_partition(mask, 16))
+
+    vl = rtlil.convert(mbool, ports=mbool.ports())
+    with open("part_bool.il", "w") as f:
+        f.write(vl)
+
+    sim = Simulator(m)
+
+    def process():
+        yield mask.eq(0b010)
+        yield mbool.a.eq(0x80c4)
+        yield Settle()
+        out = yield mbool.output
+        m = yield mask
+        a = yield mbool.a
+        print("in", hex(a), "out", bin(out), "mask", bin(m))
+
+        yield mask.eq(0b111)
+        yield Settle()
+        out = yield mbool.output
+        m = yield mask
+        a = yield mbool.a
+        print("in", hex(a), "out", bin(out), "mask", bin(m))
+
+        yield mask.eq(0b010)
+        yield Settle()
+        out = yield mbool.output
+        m = yield mask
+        a = yield mbool.a
+        print("in", hex(a), "out", bin(out), "mask", bin(m))
+
+        yield mask.eq(0b000)
+        yield mbool.a.eq(0x0300)
+        yield Settle()
+        out = yield mbool.output
+        m = yield mask
+        a = yield mbool.a
+        print("in", hex(a), "out", bin(out), "mask", bin(m))
+
+        yield mask.eq(0b010)
+        yield Settle()
+        out = yield mbool.output
+        m = yield mask
+        a = yield mbool.a
+        print("in", hex(a), "out", bin(out), "mask", bin(m))
+
+        yield mask.eq(0b111)
+        yield Settle()
+        out = yield mbool.output
+        m = yield mask
+        a = yield mbool.a
+        print("in", hex(a), "out", bin(out), "mask", bin(m))
+
+        yield mask.eq(0b010)
+        yield Settle()
+        out = yield mbool.output
+        m = yield mask
+        a = yield mbool.a
+        print("in", hex(a), "out", bin(out), "mask", bin(m))
+
+    sim.add_process(process)
+    with sim.write_vcd("part_bool.vcd", "part_bool.gtkw", traces=mbool.ports()):
+        sim.run()
+