1. C# / Говнокод #22572

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    internal unsafe static void Memcpy(byte* dest, byte* src, int len) {
            Contract.Assert(len >= 0, "Negative length in memcopy!");

            //
            // This is portable version of memcpy. It mirrors what the hand optimized assembly versions of memcpy typically do.
            //
            // Ideally, we would just use the cpblk IL instruction here. Unfortunately, cpblk IL instruction is not as efficient as
            // possible yet and so we have this implementation here for now.
            //

            switch (len)
            {
            case 0:
                return;
            case 1:
                *dest = *src;
                return;
            case 2:
                *(short *)dest = *(short *)src;
                return;
            case 3:
                *(short *)dest = *(short *)src;
                *(dest + 2) = *(src + 2);
                return;
            case 4:
                *(int *)dest = *(int *)src;
                return;
            case 5:
                *(int*)dest = *(int*)src;
                *(dest + 4) = *(src + 4);
                return;
            case 6:
                *(int*)dest = *(int*)src;
                *(short*)(dest + 4) = *(short*)(src + 4);
                return;
            case 7:
                *(int*)dest = *(int*)src;
                *(short*)(dest + 4) = *(short*)(src + 4);
                *(dest + 6) = *(src + 6);
                return;
            case 8:
#if WIN64
                *(long*)dest = *(long*)src;
#else
                *(int*)dest = *(int*)src;
                *(int*)(dest + 4) = *(int*)(src + 4);
#endif
                return;
            case 9:
#if WIN64
                *(long*)dest = *(long*)src;
#else
                *(int*)dest = *(int*)src;
                *(int*)(dest + 4) = *(int*)(src + 4);
#endif
                *(dest + 8) = *(src + 8);
                return;
            case 10:
#if WIN64
                *(long*)dest = *(long*)src;
#else
                *(int*)dest = *(int*)src;
                *(int*)(dest + 4) = *(int*)(src + 4);
#endif
                *(short*)(dest + 8) = *(short*)(src + 8);
                return;
            case 11:
#if WIN64
                *(long*)dest = *(long*)src;
#else
                *(int*)dest = *(int*)src;
                *(int*)(dest + 4) = *(int*)(src + 4);
#endif
                *(short*)(dest + 8) = *(short*)(src + 8);
                *(dest + 10) = *(src + 10);
                return;
            case 12:
#if WIN64
                *(long*)dest = *(long*)src;
#else
                *(int*)dest = *(int*)src;
                *(int*)(dest + 4) = *(int*)(src + 4);
#endif
                *(int*)(dest + 8) = *(int*)(src + 8);
                return;
case 13:
#if WIN64
                *(long*)dest = *(long*)src;
#else
                *(int*)dest = *(int*)src;
                *(int*)(dest + 4) = *(int*)(src + 4);
#endif
                *(int*)(dest + 8) = *(int*)(src + 8);
                *(dest + 12) = *(src + 12);
                return;
            case 14:
#if WIN64
                *(long*)dest = *(long*)src;
#else
                *(int*)dest = *(int*)src;

    https://github.com/Microsoft/referencesource/blob/9da503f9ef21e8d1f2905c78d4e3e5cbb3d6f85a/mscorlib/system/buffer.cs#L266


    Memcpy из Microsoft .NET Reference Source. Выглядит как типичный код на C

    Запостил: j123123, 13 Марта 2017

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