From ea2950f85860622de92e32545ea96d968f1767f4 Mon Sep 17 00:00:00 2001
From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Mon, 6 May 2019 04:49:53 +0100
Subject: [PATCH] add LD/ST Matrix (actually sparse matrix, aka straight 1D
 array)

---
 src/scoreboard/ldst_dep_cell.py |   3 +
 src/scoreboard/ldst_matrix.py   | 133 ++++++++++++++++++++++++++++++++
 2 files changed, 136 insertions(+)
 create mode 100644 src/scoreboard/ldst_matrix.py

diff --git a/src/scoreboard/ldst_dep_cell.py b/src/scoreboard/ldst_dep_cell.py
index 7653171b..39ad6708 100644
--- a/src/scoreboard/ldst_dep_cell.py
+++ b/src/scoreboard/ldst_dep_cell.py
@@ -6,6 +6,9 @@ from nmutil.latch import SRLatch
 
 class LDSTDepCell(Elaboratable):
     """ implements 11.4.12 mitch alsup load/store dependence cell, p45
+
+        note: the OR gate on load-hold-store and store-hold-load is left
+        out, to be done in the LDST sparse matrix (accumulating).
     """
     def __init__(self):
         # inputs
diff --git a/src/scoreboard/ldst_matrix.py b/src/scoreboard/ldst_matrix.py
new file mode 100644
index 00000000..daeb1427
--- /dev/null
+++ b/src/scoreboard/ldst_matrix.py
@@ -0,0 +1,133 @@
+from nmigen.compat.sim import run_simulation
+from nmigen.cli import verilog, rtlil
+from nmigen import Module, Signal, Elaboratable, Array, Cat, Const
+
+from ldst_dep_cell import LDSTDepCell
+
+"""
+
+ 6600 LD/ST Dependency Table Matrix inputs / outputs
+ ---------------------------------------------------
+
+"""
+
+class LDSTDepMatrix(Elaboratable):
+    """ implements 11.4.12 mitch alsup LD/ST Dependency Matrix, p46
+        actually a sparse matrix along the diagonal.
+
+        load-hold-store and store-hold-load accumulate in a priority-picking
+        fashion, ORing together.  the OR gate from the dependency cell is
+        here.
+    """
+    def __init__(self, n_ldst):
+        self.n_ldst = n_ldst                  # X and Y (FUs)
+        self.load_i = Signal(n_ldst, reset_less=True)  # load pending in
+        self.stor_i = Signal(n_ldst, reset_less=True)  # store pending in
+        self.issue_i = Signal(n_ldst, reset_less=True) # Issue in
+
+        self.load_hit_i = Signal(n_ldst, reset_less=True) # load hit in
+        self.stwd_hit_i = Signal(n_ldst, reset_less=True) # store w/data hit in
+
+        # outputs
+        self.ld_hold_st_o = Signal(n_ldst, reset_less=True) # load holds st out
+        self.st_hold_ld_o = Signal(n_ldst, reset_less=True) # st holds load out
+
+    def elaborate(self, platform):
+        m = Module()
+
+        # ---
+        # matrix of dependency cells
+        # ---
+        dm = Array(LDSTDepCell() for f in range(self.n_ldst))
+        for fu in range(self.n_ldst):
+            setattr(m.submodules, "dm_fu%d" % (fu), dm[fu])
+
+        # ---
+        # connect Function Unit vector
+        # ---
+        lhs = Const(0) # start at const 0
+        shl = Const(0) # (does no harm)
+        lhs_l = []
+        shl_l = []
+        load_l = []
+        stor_l = []
+        issue_l = []
+        lh_l = []
+        sh_l = []
+        for fu in range(self.n_ldst):
+            dc = dm[fu]
+            # OR the load-hold-store / store-hold-load cell outputs in...
+            _lhs = lhs
+            _shl = shl
+            lhs = Signal(reset_less=True)
+            shl = Signal(reset_less=True)
+            m.d.comb += [lhs.eq(_lhs | dc.ld_hold_st_o),
+                         shl.eq(_shl | dc.st_hold_ld_o)
+                        ]
+            # accumulate load-hold-store / store-hold-load bits
+            lhs_l.append(lhs)
+            shl_l.append(shl)
+            # accumulate inputs (for Cat'ing later) - TODO: must be a better way
+            load_l.append(dc.load_i)
+            stor_l.append(dc.stor_i)
+            issue_l.append(dc.issue_i)
+            lh_l.append(dc.load_hit_i)
+            sh_l.append(dc.stwd_hit_i)
+
+        # connect cell inputs using Cat(*list_of_stuff)
+        m.d.comb += [Cat(*load_l).eq(self.load_i),
+                     Cat(*stor_l).eq(self.stor_i),
+                     Cat(*issue_l).eq(self.issue_i),
+                     Cat(*lh_l).eq(self.load_hit_i),
+                     Cat(*sh_l).eq(self.stwd_hit_i),
+                    ]
+        # set the load-hold-store / store-hold-load OR-accumulated outputs
+        m.d.comb += self.ld_hold_st_o.eq(Cat(*lhs_l))
+        m.d.comb += self.st_hold_ld_o.eq(Cat(*shl_l))
+
+        return m
+
+    def __iter__(self):
+        yield self.load_i  
+        yield self.stor_i
+        yield self.issue_i
+        yield self.load_hit_i
+        yield self.stwd_hit_i
+        yield self.ld_hold_st_o
+        yield self.st_hold_ld_o
+
+    def ports(self):
+        return list(self)
+
+def d_matrix_sim(dut):
+    """ XXX TODO
+    """
+    yield dut.dest_i.eq(1)
+    yield dut.issue_i.eq(1)
+    yield
+    yield dut.issue_i.eq(0)
+    yield
+    yield dut.src1_i.eq(1)
+    yield dut.issue_i.eq(1)
+    yield
+    yield dut.issue_i.eq(0)
+    yield
+    yield dut.go_read_i.eq(1)
+    yield
+    yield dut.go_read_i.eq(0)
+    yield
+    yield dut.go_write_i.eq(1)
+    yield
+    yield dut.go_write_i.eq(0)
+    yield
+
+def test_d_matrix():
+    dut = LDSTDepMatrix(n_ldst=4)
+    vl = rtlil.convert(dut, ports=dut.ports())
+    with open("test_ld_st_matrix.il", "w") as f:
+        f.write(vl)
+
+    run_simulation(dut, d_matrix_sim(dut), vcd_name='test_ld_st_matrix.vcd')
+
+if __name__ == '__main__':
+    test_d_matrix()
-- 
2.30.2