From 363cbe7aea99400c25a6006bf5b28338cdadc611 Mon Sep 17 00:00:00 2001
From: Alejandro Soto <alejandro@34project.org>
Date: Fri, 6 Oct 2023 21:06:20 -0600
Subject: tb: implement ring test

---
 tb/models/ring.py | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 tb/models/ring.py

(limited to 'tb/models/ring.py')

diff --git a/tb/models/ring.py b/tb/models/ring.py
new file mode 100644
index 0000000..45305e6
--- /dev/null
+++ b/tb/models/ring.py
@@ -0,0 +1,54 @@
+def _shift_out(val, n):
+    rhs = val & ((1 << n) - 1)
+    lhs = val >> n
+    return (lhs, rhs)
+
+def _shift_in(val, n, req=0):
+    return req << n | (val & ((1 << n) - 1))
+
+def _out(*, ttl, read, inval, reply, tag, index, data):
+    req = _shift_in(read, 1, ttl)
+    req = _shift_in(inval, 1, req)
+    req = _shift_in(reply, 1, req)
+    req = _shift_in(tag, 13, req)
+    req = _shift_in(index, 12, req)
+    req = _shift_in(data, 128, req)
+    return req.to_bytes(20, 'big')
+
+class RingSegmentModel:
+    def __init__(self):
+        self.queue = []
+
+    def recv(self, req):
+        req = int.from_bytes(req, 'big')
+        req, data = _shift_out(req, 128)
+        req, index = _shift_out(req, 12)
+        req, tag = _shift_out(req, 13)
+        req, reply = _shift_out(req, 1)
+        req, inval = _shift_out(req, 1)
+        ttl, read = _shift_out(req, 1)
+
+        if ttl > 0:
+            req = _out(ttl=(ttl - 1), read=read, inval=inval, reply=reply,
+                       tag=tag, index=index, data=data)
+
+            # Recvs de bus tienen prioridad
+            self.queue.insert(0, req)
+
+    def send(self, *, ty, tag, index, data):
+        read = 0
+        inval = 0
+
+        match ty:
+            case 'read':
+                read = 1
+            case 'inval':
+                inval = 1
+            case 'read-inval':
+                read = inval = 1
+
+        #FIXME: Bug en VPI
+        data = 0
+
+        req = _out(ttl=3, read=read, inval=inval, reply=0, tag=tag, index=index, data=data)
+        self.queue.append(req)
-- 
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