72 lines
2.2 KiB
C#
72 lines
2.2 KiB
C#
using System;
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namespace VMdemo.Core
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{
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public static class AddressTranslatorUtils
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{
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public static AddressParts SplitVirtualAddress(ulong virtualAddress, int vaBits, int offsetBits)
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{
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if (vaBits <= 0 || vaBits > 64)
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{
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throw new ArgumentOutOfRangeException(nameof(vaBits), "vaBits 必须在 1 到 64 之间。");
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}
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if (offsetBits < 0 || offsetBits >= vaBits)
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{
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throw new ArgumentOutOfRangeException(nameof(offsetBits), "offsetBits 必须满足 0 <= offsetBits < vaBits。");
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}
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var vaMask = GetBitMask(vaBits);
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if (vaBits < 64 && (virtualAddress & ~vaMask) != 0UL)
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{
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throw new ArgumentOutOfRangeException(nameof(virtualAddress), "virtualAddress 超出 vaBits 可表示范围。");
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}
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var vpnBits = vaBits - offsetBits;
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GetPageTableBitLayout(vpnBits, out _, out var l2Bits);
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var offset = virtualAddress & GetBitMask(offsetBits);
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var vpn = virtualAddress >> offsetBits;
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var l2Index = vpn & GetBitMask(l2Bits);
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var l1Index = vpn >> l2Bits;
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return new AddressParts(vpn, offset, l1Index, l2Index);
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}
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public static void GetPageTableBitLayout(int vpnBits, out int l1Bits, out int l2Bits)
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{
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if (vpnBits <= 0)
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{
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throw new ArgumentOutOfRangeException(nameof(vpnBits), "vpnBits 必须是正整数。");
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}
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l1Bits = (vpnBits + 1) / 2;
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l2Bits = vpnBits / 2;
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}
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public static string FormatSplitResult(
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ulong virtualAddress,
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int vaBits,
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int offsetBits,
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AddressParts parts)
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{
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return $"VA={virtualAddress}, VPN={parts.Vpn}, Offset={parts.Offset}, L1={parts.L1Index}, L2={parts.L2Index}, vaBits={vaBits}, offsetBits={offsetBits}";
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}
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private static ulong GetBitMask(int bits)
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{
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if (bits <= 0)
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{
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return 0UL;
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}
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if (bits >= 64)
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{
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return ulong.MaxValue;
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}
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return (1UL << bits) - 1UL;
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}
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}
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}
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