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GTANAdam/UnsafeBlockCopy.cs

Created May 11, 2021 18:15
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Lower overhead (faster) BlockCopy alternative using /unsafe
Raw
UnsafeBlockCopy.cs
// using System;
// using System.Diagnostics;
// using System.Runtime.CompilerServices;
[MethodImpl(MethodImplOptions.AggressiveInlining)]
unsafe static void BlockCopy(byte[] src, int srcOffset, byte[] dst, int dstOffset, int count)
{
Debug.Assert(src != null);
Debug.Assert(dst != null);
Debug.Assert(srcOffset >= 0 && srcOffset < src.Length);
Debug.Assert(dstOffset >= 0 && dstOffset < dst.Length);
Debug.Assert(count >= 0);
Debug.Assert(count + srcOffset <= src.Length);
Debug.Assert(count + dstOffset <= dst.Length);
fixed (byte* pSrc = &src[srcOffset])
fixed (byte* pDst = &dst[dstOffset])
{
byte* ptrSrc = pSrc;
byte* ptrDst = pDst;
SMALLTABLE:
switch (count)
{
case 0:
return;
case 1:
*ptrDst = *ptrSrc;
return;
case 2:
*(short*)ptrDst = *(short*)ptrSrc;
return;
case 3:
*(short*)(ptrDst + 0) = *(short*)(ptrSrc + 0);
*(ptrDst + 2) = *(ptrSrc + 2);
return;
case 4:
*(int*)ptrDst = *(int*)ptrSrc;
return;
case 5:
*(int*)(ptrDst + 0) = *(int*)(ptrSrc + 0);
*(ptrDst + 4) = *(ptrSrc + 4);
return;
case 6:
*(int*)(ptrDst + 0) = *(int*)(ptrSrc + 0);
*(short*)(ptrDst + 4) = *(short*)(ptrSrc + 4);
return;
case 7:
*(int*)(ptrDst + 0) = *(int*)(ptrSrc + 0);
*(short*)(ptrDst + 4) = *(short*)(ptrSrc + 4);
*(ptrDst + 6) = *(ptrSrc + 6);
return;
case 8:
*(long*)ptrDst = *(long*)ptrSrc;
return;
case 9:
*(long*)(ptrDst + 0) = *(long*)(ptrSrc + 0);
*(ptrDst + 8) = *(ptrSrc + 8);
return;
case 10:
*(long*)(ptrDst + 0) = *(long*)(ptrSrc + 0);
*(short*)(ptrDst + 8) = *(short*)(ptrSrc + 8);
return;
case 11:
*(long*)(ptrDst + 0) = *(long*)(ptrSrc + 0);
*(short*)(ptrDst + 8) = *(short*)(ptrSrc + 8);
*(ptrDst + 10) = *(ptrSrc + 10);
return;
case 12:
*(long*)ptrDst = *(long*)ptrSrc;
*(int*)(ptrDst + 8) = *(int*)(ptrSrc + 8);
return;
case 13:
*(long*)(ptrDst + 0) = *(long*)(ptrSrc + 0);
*(int*)(ptrDst + 8) = *(int*)(ptrSrc + 8);
*(ptrDst + 12) = *(ptrSrc + 12);
return;
case 14:
*(long*)(ptrDst + 0) = *(long*)(ptrSrc + 0);
*(int*)(ptrDst + 8) = *(int*)(ptrSrc + 8);
*(short*)(ptrDst + 12) = *(short*)(ptrSrc + 12);
return;
case 15:
*(long*)(ptrDst + 0) = *(long*)(ptrSrc + 0);
*(int*)(ptrDst + 8) = *(int*)(ptrSrc + 8);
*(short*)(ptrDst + 12) = *(short*)(ptrSrc + 12);
*(ptrDst + 14) = *(ptrSrc + 14);
return;
case 16:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
return;
case 17:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(ptrDst + 16) = *(ptrSrc + 16);
return;
case 18:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(short*)(ptrDst + 16) = *(short*)(ptrSrc + 16);
return;
case 19:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(short*)(ptrDst + 16) = *(short*)(ptrSrc + 16);
*(ptrDst + 18) = *(ptrSrc + 18);
return;
case 20:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(int*)(ptrDst + 16) = *(int*)(ptrSrc + 16);
return;
case 21:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(int*)(ptrDst + 16) = *(int*)(ptrSrc + 16);
*(ptrDst + 20) = *(ptrSrc + 20);
return;
case 22:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(int*)(ptrDst + 16) = *(int*)(ptrSrc + 16);
*(short*)(ptrDst + 20) = *(short*)(ptrSrc + 20);
return;
case 23:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(int*)(ptrDst + 16) = *(int*)(ptrSrc + 16);
*(short*)(ptrDst + 20) = *(short*)(ptrSrc + 20);
*(ptrDst + 22) = *(ptrSrc + 22);
return;
case 24:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(long*)(ptrDst + 16) = *(long*)(ptrSrc + 16);
return;
case 25:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(long*)(ptrDst + 16) = *(long*)(ptrSrc + 16);
*(ptrDst + 24) = *(ptrSrc + 24);
return;
case 26:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(long*)(ptrDst + 16) = *(long*)(ptrSrc + 16);
*(short*)(ptrDst + 24) = *(short*)(ptrSrc + 24);
return;
case 27:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(long*)(ptrDst + 16) = *(long*)(ptrSrc + 16);
*(short*)(ptrDst + 24) = *(short*)(ptrSrc + 24);
*(ptrDst + 26) = *(ptrSrc + 26);
return;
case 28:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(long*)(ptrDst + 16) = *(long*)(ptrSrc + 16);
*(int*)(ptrDst + 24) = *(int*)(ptrSrc + 24);
return;
case 29:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(long*)(ptrDst + 16) = *(long*)(ptrSrc + 16);
*(int*)(ptrDst + 24) = *(int*)(ptrSrc + 24);
*(ptrDst + 28) = *(ptrSrc + 28);
return;
case 30:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(long*)(ptrDst + 16) = *(long*)(ptrSrc + 16);
*(int*)(ptrDst + 24) = *(int*)(ptrSrc + 24);
*(short*)(ptrDst + 28) = *(short*)(ptrSrc + 28);
return;
case 31:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(long*)(ptrDst + 16) = *(long*)(ptrSrc + 16);
*(int*)(ptrDst + 24) = *(int*)(ptrSrc + 24);
*(short*)(ptrDst + 28) = *(short*)(ptrSrc + 28);
*(ptrDst + 30) = *(ptrSrc + 30);
return;
case 32:
*(long*)ptrDst = *(long*)ptrSrc;
*(long*)(ptrDst + 8) = *(long*)(ptrSrc + 8);
*(long*)(ptrDst + 16) = *(long*)(ptrSrc + 16);
*(long*)(ptrDst + 24) = *(long*)(ptrSrc + 24);
return;
default:
break;
}
long* lpSrc = (long*)ptrSrc;
long* ldSrc = (long*)ptrDst;
while (count >= 64)
{
*(ldSrc + 0) = *(lpSrc + 0);
*(ldSrc + 1) = *(lpSrc + 1);
*(ldSrc + 2) = *(lpSrc + 2);
*(ldSrc + 3) = *(lpSrc + 3);
*(ldSrc + 4) = *(lpSrc + 4);
*(ldSrc + 5) = *(lpSrc + 5);
*(ldSrc + 6) = *(lpSrc + 6);
*(ldSrc + 7) = *(lpSrc + 7);
if (count == 64)
return;
count -= 64;
lpSrc += 8;
ldSrc += 8;
}
if (count > 32)
{
*(ldSrc + 0) = *(lpSrc + 0);
*(ldSrc + 1) = *(lpSrc + 1);
*(ldSrc + 2) = *(lpSrc + 2);
*(ldSrc + 3) = *(lpSrc + 3);
count -= 32;
lpSrc += 4;
ldSrc += 4;
}
ptrSrc = (byte*)lpSrc;
ptrDst = (byte*)ldSrc;
goto SMALLTABLE;
}
}
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