From d571a2b45c8081c278c712c61e3f1290abf1233e Mon Sep 17 00:00:00 2001
From: Michael Nolan <mtnolan2640@gmail.com>
Date: Fri, 8 May 2020 13:23:09 -0400
Subject: [PATCH] Begin adding main ALU stage

---
 src/soc/alu/formal/proof_main_stage.py | 75 ++++++++++++++++++++++++++
 src/soc/alu/main_stage.py              | 32 +++++++++++
 src/soc/alu/pipe_data.py               | 14 +++++
 3 files changed, 121 insertions(+)
 create mode 100644 src/soc/alu/formal/proof_main_stage.py
 create mode 100644 src/soc/alu/main_stage.py

diff --git a/src/soc/alu/formal/proof_main_stage.py b/src/soc/alu/formal/proof_main_stage.py
new file mode 100644
index 00000000..4b7da69b
--- /dev/null
+++ b/src/soc/alu/formal/proof_main_stage.py
@@ -0,0 +1,75 @@
+# Proof of correctness for partitioned equal signal combiner
+# Copyright (C) 2020 Michael Nolan <mtnolan2640@gmail.com>
+
+from nmigen import Module, Signal, Elaboratable, Mux
+from nmigen.asserts import Assert, AnyConst, Assume, Cover
+from nmigen.test.utils import FHDLTestCase
+from nmigen.cli import rtlil
+
+from soc.alu.main_stage import ALUMainStage
+from soc.alu.pipe_data import ALUPipeSpec
+from soc.alu.alu_input_record import CompALUOpSubset
+from soc.decoder.power_enums import InternalOp
+import unittest
+
+
+# This defines a module to drive the device under test and assert
+# properties about its outputs
+class Driver(Elaboratable):
+    def __init__(self):
+        # inputs and outputs
+        pass
+
+    def elaborate(self, platform):
+        m = Module()
+        comb = m.d.comb
+
+        rec = CompALUOpSubset()
+        recwidth = 0
+        # Setup random inputs for dut.op
+        for p in rec.ports():
+            width = p.width
+            recwidth += width
+            comb += p.eq(AnyConst(width))
+
+        pspec = ALUPipeSpec(id_wid=2, op_wid=recwidth)
+        m.submodules.dut = dut = ALUMainStage(pspec)
+
+        a = Signal(64)
+        b = Signal(64)
+        comb += [dut.i.a.eq(a),
+                 dut.i.b.eq(b),
+                 a.eq(AnyConst(64)),
+                 b.eq(AnyConst(64))]
+                      
+
+        comb += dut.i.ctx.op.eq(rec)
+
+
+        # Assert that op gets copied from the input to output
+        for p in rec.ports():
+            name = p.name
+            rec_sig = p
+            dut_sig = getattr(dut.o.ctx.op, name)
+            comb += Assert(dut_sig == rec_sig)
+
+        with m.If(rec.insn_type == InternalOp.OP_ADD):
+            comb += Assert(dut.o.o == (a + b) & ((1<<64)-1))
+
+
+        return m
+
+class GTCombinerTestCase(FHDLTestCase):
+    def test_formal(self):
+        module = Driver()
+        self.assertFormal(module, mode="bmc", depth=4)
+        self.assertFormal(module, mode="cover", depth=4)
+    def test_ilang(self):
+        dut = Driver()
+        vl = rtlil.convert(dut, ports=[])
+        with open("main_stage.il", "w") as f:
+            f.write(vl)
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/src/soc/alu/main_stage.py b/src/soc/alu/main_stage.py
new file mode 100644
index 00000000..941f567c
--- /dev/null
+++ b/src/soc/alu/main_stage.py
@@ -0,0 +1,32 @@
+from nmigen import (Module, Signal)
+from nmutil.pipemodbase import PipeModBase
+from soc.alu.pipe_data import ALUInitialData, ALUOutputData
+from ieee754.part.partsig import PartitionedSignal
+from soc.decoder.power_enums import InternalOp
+
+
+class ALUMainStage(PipeModBase):
+    def __init__(self, pspec):
+        super().__init__(pspec, "main")
+
+    def ispec(self):
+        return ALUInitialData(self.pspec)
+
+    def ospec(self):
+        return ALUOutputData(self.pspec)
+
+    def elaborate(self, platform):
+        m = Module()
+        comb = m.d.comb
+
+        add_output = Signal(self.i.a.width + 1, reset_less=True)
+        comb += add_output.eq(self.i.a + self.i.b)
+
+
+        with m.Switch(self.i.ctx.op.insn_type):
+            with m.Case(InternalOp.OP_ADD):
+                comb += self.o.o.eq(add_output)
+
+        comb += self.o.ctx.eq(self.i.ctx)
+
+        return m
diff --git a/src/soc/alu/pipe_data.py b/src/soc/alu/pipe_data.py
index a1bbc7c3..9db5c9bc 100644
--- a/src/soc/alu/pipe_data.py
+++ b/src/soc/alu/pipe_data.py
@@ -33,6 +33,20 @@ class ALUInitialData(IntegerData):
         lst = super().eq(i)
         return lst + [self.a.eq(i.a), self.b.eq(i.b)]
 
+
+class ALUOutputData(IntegerData):
+    def __init__(self, pspec):
+        super().__init__(pspec)
+        self.o = Signal(64, reset_less=True)
+
+    def __iter__(self):
+        yield from super().__iter__()
+        yield self.o
+
+    def eq(self, i):
+        lst = super().eq(i)
+        return lst + [self.o.eq(i.o)]
+
 class IntPipeSpec:
     def __init__(self, id_wid=2, op_wid=1):
         self.id_wid = id_wid
-- 
2.30.2