From 19b870f778276ddb6cca1a42bf48255c2072e8b0 Mon Sep 17 00:00:00 2001
From: Daniel Benusovich <flyingmonkeys1996@gmail.com>
Date: Sun, 10 Feb 2019 22:42:46 -0800
Subject: [PATCH] Inital Version of the TLB. Very far from complete. Needs at
 some additional modules

---
 TLB/TLB.py | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 TLB/TLB.py

diff --git a/TLB/TLB.py b/TLB/TLB.py
new file mode 100644
index 00000000..c708419b
--- /dev/null
+++ b/TLB/TLB.py
@@ -0,0 +1,66 @@
+from nmigen import *
+from nmigen.cli import main
+from PermissionValidator import PermissionValidator
+
+class TLB():
+    def __init__(self):
+        # Inputs
+        self.xwr = Signal(3) # Execute, Write, Read
+        self.super = Signal(1) # Supervisor Mode
+        self.super_access = Signal(1) # Supervisor Access
+        self.command = Signal(2) # 00=None, 01=Search, 10=Write PTE, 11=Reset
+        self.mode = Signal(4) # 4 bits for access to Sv48 on Rv64
+        self.asid = Signal(15) # Address Space IDentifier (ASID)
+        self.vma = Signal(36) # Virtual Memory Address (VMA)
+        self.pte_in = Signal(64) # To be saved Page Table Entry (PTE)
+        
+        # Outputs
+        self.hit = Signal(1) # Denotes if the VMA had a mapped PTE
+        self.valid = Signal(1) # Denotes if the permissions are correct
+        self.pteOut = Signal(64) # PTE that was mapped to by the VMA
+        
+        # Cam simulations
+        mem_l1 = Memory(113, 32) # L1 TLB cache
+        read_port_l1 = mem_l1.read_port
+        write_port_l1 = mem_l1.write_port
+        
+        mem_l2 = Memory(113, 128) # L2 TLB cache
+        read_port_l2 = mem_l2.read_port
+        write_port_l2 = mem_l2.write_port
+        
+        def elaborate(self, platform):
+            m = Module()
+            m.d.submodules.perm_valid = perm_valid = PermissionValidator(113)
+            m.d.sync += [
+                Case(self.command, {
+                   # Search for PTE
+                   1: [
+                       # Check first entry in set
+                       # TODO make module?
+                       read_port_l1.addr.eq(vma[0,2]),
+                       If(read_port_l1.data[0] == 1,
+                          perm_valid.data.eq(read_port_l1.data),
+                          perm_valid.xwr.eq(self.xwr),
+                          perm_valid.super.eq(self.super),
+                          perm_valid.super_access.eq(self.super_access),
+                          perm_valid.asid.eq(self.asid),
+                          self.valid,eq(perm_valid.valid)
+                       ),
+                       If(self.valid == 0,
+                          read_port_l1.addr.eq(vma[0,2] + 1),
+                          If(read_port_l1.data[0] == 1,
+                             perm_valid.data.eq(read_port_l1.data),
+                             perm_valid.xwr.eq(self.xwr),
+                             perm_valid.super.eq(self.super),
+                             perm_valid.super_access.eq(self.super_access),
+                             perm_valid.asid.eq(self.asid),
+                             self.valid,eq(perm_valid.valid)
+                          )                          
+                       )
+                       ]
+                })
+            ]
+        
+thing = TLB()
+print("Gottem")
+        
\ No newline at end of file
-- 
2.30.2