46 lines
1.2 KiB
Plaintext
46 lines
1.2 KiB
Plaintext
////////////////////////////////////////////////////////////////////////////////
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//
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// Microsoft Research Singularity
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//
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//
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// File: StateStack.cs
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//
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// Note: File is part of Sing# runtime files and copied into Singularity tree
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// whenever a new version of Sing# is dropped.
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//
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using System;
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using Microsoft.Contracts;
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namespace Microsoft.Singularity.Channels {
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public pointerfree struct StateStack {
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public const int STATEBITS = 8;
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public const int STATEMASK = (1 << STATEBITS) - 1;
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private uint stack; // 4 x 8 bits for state of machine of this endpoint. Lowest bits = top of stack
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public StateStack(int initialState) {
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stack = (uint)initialState & STATEMASK;
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}
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public void Push(int i) {
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stack = stack << STATEBITS | ((uint)i & STATEMASK);
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}
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public void Pop() {
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stack = stack >> STATEBITS;
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}
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public void Set(int i) {
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stack = (stack & (uint)~(uint)STATEMASK) | ((uint)i & STATEMASK);
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}
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[Pure]
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public int Top() {
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return (int)(stack & STATEMASK);
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}
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}
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}
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