88 lines
2.7 KiB
JavaScript
88 lines
2.7 KiB
JavaScript
/*
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* Copyright (C) 2017 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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"use strict";
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class EPtr {
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constructor(buffer, offset)
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{
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if (offset == null || offset != offset)
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throw new Error("Bad offset: " + offset);
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this._buffer = buffer;
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this._offset = offset;
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}
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// The interpreter always passes around pointers to things. This means that sometimes we will
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// want to return a value but we have to "invent" a pointer to that value. No problem, this
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// function is here to help.
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//
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// In a real execution environment, uses of this manifest as SSA temporaries.
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static box(value)
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{
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return new EPtr(new EBuffer(1), 0).box(value);
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}
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box(value)
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{
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this._buffer.set(0, value);
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return this;
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}
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get buffer() { return this._buffer; }
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get offset() { return this._offset; }
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plus(offset)
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{
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return new EPtr(this.buffer, this.offset + offset);
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}
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loadValue()
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{
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return this.buffer.get(this.offset);
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}
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get(offset)
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{
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return this.buffer.get(this.offset + offset);
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}
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set(offset, value)
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{
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this.buffer.set(this.offset + offset, value);
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}
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copyFrom(other, size)
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{
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if (size == null)
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throw new Error("Cannot copy null size");
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for (let i = size; i--;)
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this.set(i, other.get(i));
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}
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toString()
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{
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return "B" + this.buffer.index + ":" + this.offset;
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}
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}
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