Step 2 - 地址生成与拆分

2026-04-14 00:56:38 +08:00
parent 7eab504f4a
commit 4ab93d7806
7 changed files with 266 additions and 10 deletions
@@ -0,0 +1,71 @@
+using System;
+
+namespace VMdemo.Core
+{
+    public static class AddressTranslatorUtils
+    {
+        public static AddressParts SplitVirtualAddress(ulong virtualAddress, int vaBits, int offsetBits)
+        {
+            if (vaBits <= 0 || vaBits > 64)
+            {
+                throw new ArgumentOutOfRangeException(nameof(vaBits), "vaBits 必须在 1 到 64 之间。");
+            }
+
+            if (offsetBits < 0 || offsetBits >= vaBits)
+            {
+                throw new ArgumentOutOfRangeException(nameof(offsetBits), "offsetBits 必须满足 0 <= offsetBits < vaBits。");
+            }
+
+            var vaMask = GetBitMask(vaBits);
+            if (vaBits < 64 && (virtualAddress & ~vaMask) != 0UL)
+            {
+                throw new ArgumentOutOfRangeException(nameof(virtualAddress), "virtualAddress 超出 vaBits 可表示范围。");
+            }
+
+            var vpnBits = vaBits - offsetBits;
+            GetPageTableBitLayout(vpnBits, out _, out var l2Bits);
+
+            var offset = virtualAddress & GetBitMask(offsetBits);
+            var vpn = virtualAddress >> offsetBits;
+            var l2Index = vpn & GetBitMask(l2Bits);
+            var l1Index = vpn >> l2Bits;
+
+            return new AddressParts(vpn, offset, l1Index, l2Index);
+        }
+
+        public static void GetPageTableBitLayout(int vpnBits, out int l1Bits, out int l2Bits)
+        {
+            if (vpnBits <= 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(vpnBits), "vpnBits 必须是正整数。");
+            }
+
+            l1Bits = (vpnBits + 1) / 2;
+            l2Bits = vpnBits / 2;
+        }
+
+        public static string FormatSplitResult(
+            ulong virtualAddress,
+            int vaBits,
+            int offsetBits,
+            AddressParts parts)
+        {
+            return $"VA={virtualAddress}, VPN={parts.Vpn}, Offset={parts.Offset}, L1={parts.L1Index}, L2={parts.L2Index}, vaBits={vaBits}, offsetBits={offsetBits}";
+        }
+
+        private static ulong GetBitMask(int bits)
+        {
+            if (bits <= 0)
+            {
+                return 0UL;
+            }
+
+            if (bits >= 64)
+            {
+                return ulong.MaxValue;
+            }
+
+            return (1UL << bits) - 1UL;
+        }
+    }
+}
@@ -0,0 +1,11 @@
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