e655606d45
+ merging of js/src and js/ref + elimination of most dependencies on NSPR + JS1.4 feature additions and accumulated bug fixes More details are in last week's mozilla status report. git-svn-id: svn://10.0.0.236/trunk@12797 18797224-902f-48f8-a5cc-f745e15eee43
63 lines
1.5 KiB
C
63 lines
1.5 KiB
C
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/*
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* The contents of this file are subject to the Netscape Public License
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* Version 1.0 (the "NPL"); you may not use this file except in
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* compliance with the NPL. You may obtain a copy of the NPL at
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* http://www.mozilla.org/NPL/
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*
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* Software distributed under the NPL is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
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* for the specific language governing rights and limitations under the
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* NPL.
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*
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* The Initial Developer of this code under the NPL is Netscape
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* Communications Corporation. Portions created by Netscape are
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* Copyright (C) 1998 Netscape Communications Corporation. All Rights
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* Reserved.
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*/
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#include "jsbit.h"
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/*
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** Compute the log of the least power of 2 greater than or equal to n
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*/
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JS_EXPORT_API(JSIntn) JS_CeilingLog2(JSUint32 n)
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{
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JSIntn log2 = 0;
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if (n & (n-1))
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log2++;
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if (n >> 16)
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log2 += 16, n >>= 16;
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if (n >> 8)
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log2 += 8, n >>= 8;
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if (n >> 4)
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log2 += 4, n >>= 4;
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if (n >> 2)
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log2 += 2, n >>= 2;
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if (n >> 1)
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log2++;
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return log2;
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}
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/*
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** Compute the log of the greatest power of 2 less than or equal to n.
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** This really just finds the highest set bit in the word.
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*/
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JS_EXPORT_API(JSIntn) JS_FloorLog2(JSUint32 n)
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{
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JSIntn log2 = 0;
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if (n >> 16)
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log2 += 16, n >>= 16;
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if (n >> 8)
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log2 += 8, n >>= 8;
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if (n >> 4)
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log2 += 4, n >>= 4;
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if (n >> 2)
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log2 += 2, n >>= 2;
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if (n >> 1)
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log2++;
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return log2;
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}
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