__FastResourceComparer.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / clr / src / BCL / System / Resources / __FastResourceComparer.cs / 1 / __FastResourceComparer.cs
                        

                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
/*============================================================
** 
** Class:  FastResourceComparer 
**
** 
** Purpose: A collection of quick methods for comparing
**          resource keys (strings)
**
** 
===========================================================*/
namespace System.Resources { 
    using System; 
    using System.Collections;
    using System.Collections.Generic; 

    internal sealed class FastResourceComparer : IComparer, IEqualityComparer, IComparer, IEqualityComparer
    {
        internal static readonly FastResourceComparer Default = new FastResourceComparer(); 

        // Implements IHashCodeProvider too, due to Hashtable requirements. 
        public int GetHashCode(Object key) 
        {
            String s = (String) key; 
            return FastResourceComparer.HashFunction(s);
        }

        public int GetHashCode(String key) 
        {
            return FastResourceComparer.HashFunction(key); 
        } 

        // This hash function MUST be publically documented with the resource 
        // file format, AND we may NEVER change this hash function's return
        // value (without changing the file format).
        internal static int HashFunction(String key)
        { 
            // Never change this hash function.  We must standardize it so that
            // others can read & write our .resources files.  Additionally, we 
            // have a copy of it in InternalResGen as well. 
            uint hash = 5381;
            for(int i=0; i bCharLength)
                numChars = bCharLength; 
            if (bCharLength == 0)   // Can't use fixed on a 0-element array.
                return (a.Length == 0) ? 0 : -1;
            fixed(byte* pb = bytes) {
 
                byte *pChar = pb;
                while (i < numChars && r == 0) { 
                    // little endian format 
                    int b = pChar[0] | pChar[1] << 8;
                    r = a[i++] - b; 
                    pChar += sizeof(char);
                }
            }
            if (r != 0) return r; 
            return a.Length - bCharLength;
        } 
 
        public static int CompareOrdinal(byte[] bytes, int aCharLength, String b)
        { 
            return -CompareOrdinal(b, bytes, aCharLength);
        }

        // This method is to handle potentially misaligned data accesses. 
        // The byte* must point to little endian Unicode characters.
        internal unsafe static int CompareOrdinal(byte* a, int byteLen, String b) 
        { 
            BCLDebug.Assert((byteLen & 1) == 0, "CompareOrdinal is expecting a UTF-16 string length, which must be even!");
            BCLDebug.Assert(a != null && b != null, "Null args not allowed."); 
            BCLDebug.Assert(byteLen >= 0, "byteLen must be non-negative.");

            int r = 0;
            int i = 0; 
            // Compare the min length # of characters, then return length diffs.
            int numChars = byteLen >> 1; 
            if (numChars > b.Length) 
                numChars = b.Length;
            while(i < numChars && r == 0) { 
                // Must compare character by character, not byte by byte.
                char aCh = (char) (*a++ | (*a++ << 8));
                r = aCh - b[i++];
            } 
            if (r != 0) return r;
            return byteLen - b.Length * 2; 
        } 
    }
}

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