Modified source engine (2017) developed by valve and leaked in 2020. Not for commercial purporses
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//========= Copyright Valve Corporation, All rights reserved. ============//
//
// UnDiff - Apply difference block
//
//=============================================================================//
#include "tier0/platform.h"
#include "tier0/dbg.h"
#include "tier1/diff.h"
#include "mathlib/mathlib.h"
// memdbgon must be the last include file in a .cpp file!!!
#include "tier0/memdbgon.h"
void ApplyDiffs(uint8 const *OldBlock, uint8 const *DiffList,
int OldSize, int DiffListSize, int &ResultListSize,uint8 *Output,uint32 OutSize)
{
uint8 const *copy_src=OldBlock;
uint8 const *end_of_diff_list=DiffList+DiffListSize;
uint8 const *obuf=Output;
while(DiffList<end_of_diff_list)
{
// printf("dptr=%x ",DiffList-d);
uint8 op=*(DiffList++);
if (op==0)
{
uint16 copy_sz=DiffList[0]+256*DiffList[1];
int copy_ofs=DiffList[2]+DiffList[3]*256;
if (copy_ofs>32767)
copy_ofs|=0xffff0000;
// printf("long cp from %x to %x len=%d\n", copy_src+copy_ofs-OldBlock,Output-obuf,copy_sz);
memcpy(Output,copy_src+copy_ofs,copy_sz);
Output+=copy_sz;
copy_src=copy_src+copy_ofs+copy_sz;
DiffList+=4;
}
else
{
if (op & 0x80)
{
int copy_sz=op & 0x7f;
int copy_ofs;
if (copy_sz==0)
{
copy_sz=DiffList[0];
if (copy_sz==0)
{
// big raw copy
copy_sz=DiffList[1]+256*DiffList[2]+65536*DiffList[3];
memcpy(Output,DiffList+4,copy_sz);
// printf("big rawcopy to %x len=%d\n", Output-obuf,copy_sz);
DiffList+=copy_sz+4;
Output+=copy_sz;
}
else
{
copy_ofs=DiffList[1]+(DiffList[2]*256);
if (copy_ofs>32767)
copy_ofs|=0xffff0000;
// printf("long ofs cp from %x to %x len=%d\n", copy_src+copy_ofs-OldBlock,Output-obuf,copy_sz);
memcpy(Output,copy_src+copy_ofs,copy_sz);
Output+=copy_sz;
copy_src=copy_src+copy_ofs+copy_sz;
DiffList+=3;
}
}
else
{
copy_ofs=DiffList[0];
if (copy_ofs>127)
copy_ofs|=0xffffff80;
// printf("cp from %x to %x len=%d\n", copy_src+copy_ofs-OldBlock,Output-obuf,copy_sz);
memcpy(Output,copy_src+copy_ofs,copy_sz);
Output+=copy_sz;
copy_src=copy_src+copy_ofs+copy_sz;
DiffList++;
}
}
else
{
// printf("raw copy %d to %x\n",op & 127,Output-obuf);
memcpy(Output,DiffList,op & 127);
Output+=op & 127;
DiffList+=(op & 127);
}
}
}
ResultListSize=Output-obuf;
}