From: Michael Nolan <mtnolan2640@gmail.com>
Date: Mon, 10 Feb 2020 14:42:34 +0000 (-0500)
Subject: Add neg operator to partsig.py
X-Git-Tag: ls180-24jan2020~207
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=1480761db420032eb229e737658fcb6bed3aec99;p=ieee754fpu.git

Add neg operator to partsig.py
---

diff --git a/src/ieee754/part/partsig.py b/src/ieee754/part/partsig.py
index a4cad8d6..833451db 100644
--- a/src/ieee754/part/partsig.py
+++ b/src/ieee754/part/partsig.py
@@ -61,8 +61,8 @@ class PartitionedSignal:
     # unary ops that require partitioning
 
     def __neg__(self):
-        # TODO use PartitionedAdder for this, with a "neg" mode?
-        return Operator("-", [self])
+        result, _ = self.add_op(self, ~0, carry=0) # TODO, subop
+        return result
 
     # binary ops that don't require partitioning
 
diff --git a/src/ieee754/part/test/test_partsig.py b/src/ieee754/part/test/test_partsig.py
index ce8464c9..cc881be3 100644
--- a/src/ieee754/part/test/test_partsig.py
+++ b/src/ieee754/part/test/test_partsig.py
@@ -49,6 +49,7 @@ class TestAddMod(Elaboratable):
         self.carry_in = Signal(len(partpoints)+1)
         self.add_carry_out = Signal(len(partpoints)+1)
         self.sub_carry_out = Signal(len(partpoints)+1)
+        self.neg_output = Signal(width)
 
     def elaborate(self, platform):
         m = Module()
@@ -71,6 +72,7 @@ class TestAddMod(Elaboratable):
                                                self.carry_in)
             m.d.comb += self.sub_output.eq(sub_out)
             m.d.comb += self.sub_carry_out.eq(add_carry)
+        m.d.comb += self.neg_output.eq(-self.a)
         ppts = self.partpoints
         m.d.comb += self.mux_out.eq(PMux(m, ppts, self.mux_sel, self.a, self.b))
 
@@ -100,6 +102,10 @@ class TestPartitionPoints(unittest.TestCase):
                 lsb = mask & ~(mask-1) if carry_in else 0
                 return mask & ((a & mask) + (~b & mask) + lsb)
 
+            def test_neg_fn(carry_in, a, b, mask):
+                lsb = mask & ~(mask-1) if carry_in else 0
+                return mask & ((a & mask) + (~0 & mask)) 
+
             def test_op(msg_prefix, carry, test_fn, mod_attr, *mask_list):
                 rand_data = []
                 for i in range(100):
@@ -129,6 +135,7 @@ class TestPartitionPoints(unittest.TestCase):
 
             for (test_fn, mod_attr) in ((test_add_fn, "add"),
                                         (test_sub_fn, "sub"),
+                                        (test_neg_fn, "neg"),
                                         ):
                 yield part_mask.eq(0)
                 yield from test_op("16-bit", 1, test_fn, mod_attr, 0xFFFF)