擂台：改进 String.CompareOrdinal 性能

[FengYuanMSFT]

重新实现 String.CompareOrdinal，用 C#，不能调用 native code, 使下面程序最快 （Total time)，提供前后数据

        static int StringCompare(string s1, string s2)
        {
            return String.CompareOrdinal(s1, s2);
        }

        static double CompareLoop(string s1, string s2, int count, out int result)
        {
            result = 0;

            DateTime start = DateTime.Now;

            for (int i = 0; i < count; i++)
            {
                result += StringCompare(s1, s2);
            }

            return (DateTime.Now - start).TotalMilliseconds;
        }

        static void Main(string[] args)
        {
            string s0 = "A quick brown fox jumps over a lady jog. ";

            string s1 = String.Empty;

            for (int i = 0; i < 10; i++)
            {
                s1 = s1 + s0;
            }

            string s2 = s1 + "A";

            int count = 10 * 1000 * 1000;

            int result1;
            int result2;

            double t1 = CompareLoop("a", "b", count * 10, out result1);
            double t2 = CompareLoop(s1, s2, count, out result2);

            Console.WriteLine("Short {0} ms {1} ", t1, result1);
            Console.WriteLine("Long  {0} ms {1} ", t2, result2);

            Console.WriteLine("Total time {0} ms", t1 + t2);
        }

[rabbit342]

study~

[threenewbee]

mark下，回头来看。

不用Native Code有难度。

[FengYuanMSFT]

if (*((long*)pa) != *((long*)pb))
{
return charCount;
}

return charCount 是错的，应该看第一个字符的差。

[dcba987654]

哎，太复杂

[huwei001982]

居然可以用 unsafe 指针， 不是不能调用 native code 吗

[yaojianqiyinshan]

哎，太复杂

[yunzhenwang]

学习中，不错不错

[RLib]

呵呵。。。。。。。。。。用系统的

[petrie]

[KOSymbian]

[Quote=引用 67 楼 ktei2008 的回复:]
比这个能比出什么来？效率差别不在于这个
[/Quote]

厉害啊！！！！

[ktei2008]

比这个能比出什么来？效率差别不在于这个

[zlcp520]

内容存入剪贴

[abs102]

这么长。。。

[张见]

过来 学习下

[s1308842]

不是很明白呀。

[yhnujm##33]

牛逼！！！！！！

[viki117]

private static unsafe int CompareOrdinalHelper(string strA, string strB)
{
    int num = Math.Min(strA.Length, strB.Length);
    int num2 = -1;
    fixed (char* chRef = &strA.m_firstChar)
    {
        fixed (char* chRef2 = &strB.m_firstChar)
        {
            char* chPtr = chRef;
            char* chPtr2 = chRef2;
            while (num >= 10)
            {
                if (*(((int*)chPtr)) != *(((int*)chPtr2)))
                {
                    num2 = 0;
                    break;
                }
                if (*(((int*)(chPtr + 2))) != *(((int*)(chPtr2 + 2))))
                {
                    num2 = 2;
                    break;
                }
                if (*(((int*)(chPtr + 4))) != *(((int*)(chPtr2 + 4))))
                {
                    num2 = 4;
                    break;
                }
                if (*(((int*)(chPtr + 6))) != *(((int*)(chPtr2 + 6))))
                {
                    num2 = 6;
                    break;
                }
                if (*(((int*)(chPtr + 8))) != *(((int*)(chPtr2 + 8))))
                {
                    num2 = 8;
                    break;
                }
                chPtr += 10;
                chPtr2 += 10;
                num -= 10;
            }
            if (num2 == -1)
            {
                goto Label_00F1;
            }
            chPtr += num2;
            chPtr2 += num2;
            int num3 = chPtr[0] - chPtr2[0];
            if (num3 != 0)
            {
                return num3;
            }
            return (chPtr[1] - chPtr2[1]);
        Label_00D7:
            if (*(((int*)chPtr)) != *(((int*)chPtr2)))
            {
                goto Label_00F5;
            }
            chPtr += 2;
            chPtr2 += 2;
            num -= 2;
        Label_00F1:
            if (num > 0)
            {
                goto Label_00D7;
            }
        Label_00F5:
            if (num > 0)
            {
                int num4 = chPtr[0] - chPtr2[0];
                if (num4 != 0)
                {
                    return num4;
                }
                return (chPtr[1] - chPtr2[1]);
            }
            return (strA.Length - strB.Length);
        }
    }
}

[「已注销」]

[Quote=引用 101 楼 viki117 的回复:]
……
[/Quote]

fixed (char* chRef2 = &strB.m_firstChar)
楼上的m_firstChar是哪里来的? 这个是private的字段你肿么能用?

[「已注销」]

哥们能结贴了不....

[showjim]

private static unsafe int StringCompare(string left, string right)
        {
            if (left != null)
            {
                if (right != null)
                {
                    int value = left.Length - right.Length, length = value <= 0 ? left.Length : right.Length;
                    fixed (char* leftFixed = left, rightFixed = right)
                    {
                        byte* leftStart = (byte*)leftFixed, rightStart = (byte*)rightFixed;
                        while (length >= 8)
                        {
                            uint code = (*(uint*)leftStart ^ *(uint*)rightStart) | (*(uint*)(leftStart + 4) ^ *(uint*)(rightStart + 4));
                            if ((code | (*(uint*)(leftStart + 8) ^ *(uint*)(rightStart + 8))
                                | (*(uint*)(leftStart + 12) ^ *(uint*)(rightStart + 12))) != 0)
                            {
                                if (code == 0)
                                {
                                    leftStart += 8;
                                    rightStart += 8;
                                }
                                if (*(uint*)leftStart == *(uint*)rightStart)
                                {
                                    leftStart += 4;
                                    rightStart += 4;
                                }
                                value = (int)*(ushort*)leftStart - *(ushort*)rightStart;
                                return value == 0 ? (int)*(ushort*)(leftStart += 2) - *(ushort*)(rightStart += 2) : value;
                            }
                            length -= 8;
                            leftStart += 16;
                            rightStart += 16;
                        }
                        if ((length & 4) != 0)
                        {
                            uint code = *(uint*)leftStart ^ *(uint*)rightStart;
                            if ((code | (*(uint*)(leftStart + 4) ^ *(uint*)(rightStart + 4))) != 0)
                            {
                                if (code == 0)
                                {
                                    leftStart += 4;
                                    rightStart += 4;
                                }
                                value = (int)*(ushort*)leftStart - *(ushort*)rightStart;
                                return value == 0 ? (int)*(ushort*)(leftStart += 2) - *(ushort*)(rightStart += 2) : value;
                            }
                            leftStart += 8;
                            rightStart += 8;
                        }
                        if ((length & 2) != 0)
                        {
                            int code = (int)*(ushort*)leftStart - *(ushort*)rightStart;
                            if (code != 0) return code;
                            code = (int)*(ushort*)(leftStart + 2) - *(ushort*)(rightStart + 2);
                            if (code != 0) return code;
                            leftStart += 4;
                            rightStart += 4;
                        }
                        if ((length & 1) != 0)
                        {
                            int code = (int)*(ushort*)leftStart - *(ushort*)rightStart;
                            if (code != 0) return code;
                        }
                    }
                    return value;
                }
                return 1;
            }
            return right != null ? -1 : 0;
        }