From 5646e19dc378dd6facf06f3feb3921e137a8fd4f Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sb@m-labs.hk>
Date: Sun, 10 Sep 2017 14:38:43 +0800
Subject: [PATCH] rtio/sed: add output network (untested)

---
 artiq/gateware/rtio/sed/__init__.py       |  0
 artiq/gateware/rtio/sed/output_network.py | 95 +++++++++++++++++++++++
 2 files changed, 95 insertions(+)
 create mode 100644 artiq/gateware/rtio/sed/__init__.py
 create mode 100644 artiq/gateware/rtio/sed/output_network.py

diff --git a/artiq/gateware/rtio/sed/__init__.py b/artiq/gateware/rtio/sed/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/artiq/gateware/rtio/sed/output_network.py b/artiq/gateware/rtio/sed/output_network.py
new file mode 100644
index 000000000..7c48caac3
--- /dev/null
+++ b/artiq/gateware/rtio/sed/output_network.py
@@ -0,0 +1,95 @@
+from migen import *
+
+
+# Based on: https://github.com/Bekbolatov/SortingNetworks/blob/master/src/main/js/gr.js
+def boms_get_partner(n, l, p):
+    if p == 1:
+        return n ^ (1 << (l - 1))
+    scale = 1 << (l - p)
+    box = 1 << p
+    sn = n//scale - n//scale//box*box
+    if sn == 0 or sn == (box - 1):
+        return n
+    if (sn % 2) == 0:
+        return n - scale
+    return n + scale
+
+
+def boms_steps_pairs(node_count):
+    d = log2_int(node_count)
+    steps = []
+    for l in range(1, d+1):
+        for p in range(1, l+1):
+            pairs = []
+            for n in range(2**d):
+                partner = boms_get_partner(n, l, p)
+                if partner != n:
+                    if partner > n:
+                        pair = (n, partner)
+                    else:
+                        pair = (partner, n)
+                    if pair not in pairs:
+                        pairs.append(pair)
+            steps.append(pairs)
+    return steps
+
+
+layout_rtio_payload = [
+    ("channel", 24),
+    ("timestamp", 64),
+    ("address", 16),
+    ("data", 512),
+]
+
+
+def layout_node_data(seqn_size):
+    return [
+        ("valid", 1),
+        ("seqn", seqn_size),
+        ("replace_occured", 1),
+        ("payload", layout_rtio_payload)
+    ]
+
+
+def cmp_wrap(a, b):
+    return Mux(a[-2:] == ~b[-2:], a[0], a[:-2] < b[:-2])
+
+
+class OutputNetwork(Module):
+    def __init__(self, node_count, seqn_size):
+        self.input = [Record(layout_node_data(seqn_size)) for _ in node_count]
+        self.output = None
+
+        step_input = self.input
+        for step in boms_steps_pairs(node_count):
+            step_output = [Record(layout_node_data(seqn_size)) for _ in node_count]
+
+            for node1, node2 in step:
+                self.sync += [
+                    If(step_input[node1].payload.channel == step_input[node2].payload.channel,
+                        If(cmp_wrap(step_input[node1].seqn, step_input[node2].seqn),
+                            step_output[node1].eq(step_output[node2]),
+                        ).Else(
+                            step_output[node1].eq(step_output[node1]),
+                        ),
+                        step_output[node1].replace_occured.eq(1),
+                        step_output[node2].eq(step_input[node2]),
+                        step_output[node2].valid.eq(0)
+                    ).Elif(step_input[node1].payload.channel < step_input[node2].payload.channel,
+                        step_output[node1].eq(step_input[node1]),
+                        step_output[node2].eq(step_input[node2])
+                    ).Else(
+                        step_output[node1].eq(step_input[node2]),
+                        step_output[node2].eq(step_input[node1])
+                    )
+                ]
+
+            unchanged = list(range(node_count))
+            for node1, node2 in step:
+                unchanged.remove(node1)
+                unchanged.remove(node2)
+            for node in unchanged:
+                self.sync += step_output[node].eq(step_input[node])
+
+            self.output = step_output
+            step_input = step_output