From 39ed87570bdb2f86969d4be821c94b722dc71179 Mon Sep 17 00:00:00 2001
From: Joe Ludwig <joe@valvesoftware.com>
Date: Wed, 26 Jun 2013 15:22:04 -0700
Subject: First version of the SOurce SDK 2013

---
 mp/src/tier1/diff.cpp | 547 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 547 insertions(+)
 create mode 100644 mp/src/tier1/diff.cpp

(limited to 'mp/src/tier1/diff.cpp')

diff --git a/mp/src/tier1/diff.cpp b/mp/src/tier1/diff.cpp
new file mode 100644
index 00000000..42deb231
--- /dev/null
+++ b/mp/src/tier1/diff.cpp
@@ -0,0 +1,547 @@
+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose:
+//
+// $NoKeywords: $
+//=============================================================================//
+
+#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"
+
+
+// format of diff output:
+// 0NN (N=1..127)  copy next N literaly
+//
+// 1NN (N=1..127) ofs (-128..127) copy next N bytes from original, changin offset by N bytes from
+// last copy end
+// 100 N ofs(-32768..32767) copy next N, with larger delta offset
+// 00 NNNN(1..65535) ofs(-32768..32767) big copy from old
+// 80 00 NN NN NN big raw copy
+//
+// available codes (could be used for additonal compression ops)
+// long offset form whose offset could have fit in short offset
+
+// note - this algorithm uses storage equal to 8* the old buffer size. 64k=.5mb
+
+
+#define MIN_MATCH_LEN 8
+#define ACCEPTABLE_MATCH_LEN 4096
+
+struct BlockPtr
+{
+  BlockPtr *Next;
+  uint8 const *dataptr;
+};
+
+template<class T,class V> static inline void AddToHead(T * & head, V * node)
+{
+   node->Next=head;
+   head=node;
+}  
+
+void Fail(char const *msg)
+{
+	Assert(0);
+}
+
+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;
+  
+}
+
+static void CopyPending(int len, uint8 const *rawbytes,uint8 * &outbuf, uint8 const *limit)
+{
+//    printf("copy raw len=%d\n",len);
+  if (len<128)
+  {
+    if (limit-outbuf < len+1)
+      Fail("diff buffer overrun");
+    *(outbuf++)=len;
+    memcpy(outbuf,rawbytes,len);
+    outbuf+=len;
+  }
+  else
+  {
+    if (limit-outbuf < len+5)
+      Fail("diff buffer overrun");
+    *(outbuf++)=0x80;
+    *(outbuf++)=0x00;
+    *(outbuf++)=(len & 255);
+    *(outbuf++)=((len>>8) & 255);
+    *(outbuf++)=((len>>16) & 255);
+    memcpy(outbuf,rawbytes,len);
+    outbuf+=len;
+  }
+}
+
+static uint32 hasher(uint8 const *mdata)
+{
+  // attempt to scramble the bits of h1 and h2 together
+  uint32 ret=0;
+  for(int i=0;i<MIN_MATCH_LEN;i++)
+  {
+    ret=ret<<4;
+    ret+=(*mdata++);
+  }
+  return ret;
+}
+
+int FindDiffsForLargeFiles(uint8 const *NewBlock, uint8 const *OldBlock,
+                            int NewSize, int OldSize, int &DiffListSize,uint8 *Output,
+                            uint32 OutSize,
+                            int hashsize)
+{
+  
+  int ret=0;
+  if (OldSize!=NewSize)
+    ret=1;
+  // first, build the hash table
+  BlockPtr **HashedMatches=new BlockPtr* [hashsize];
+  memset(HashedMatches,0,sizeof(HashedMatches[0])*hashsize);
+  BlockPtr *Blocks=0;
+  if (OldSize)
+    Blocks=new BlockPtr[OldSize];
+  BlockPtr *FreeList=Blocks;
+  // now, build the hash table
+  uint8 const *walk=OldBlock;
+  if (OldBlock && OldSize)
+    while(walk<OldBlock+OldSize-MIN_MATCH_LEN)
+    {
+      uint32 hash1=hasher(walk);
+      hash1 &=(hashsize-1);
+      BlockPtr *newnode=FreeList;
+      FreeList++;
+      newnode->dataptr=walk;
+      AddToHead(HashedMatches[hash1],newnode);
+      walk++;
+    }
+  else
+    ret=1;
+  // now, we have the hash table which may be used to search. begin the output step
+  int pending_raw_len=0;
+  walk=NewBlock;
+  uint8 *outbuf=Output;
+  uint8 const *lastmatchend=OldBlock;
+  while(walk<NewBlock+NewSize)
+  {
+    int longest=0;
+    BlockPtr *longest_block=0;
+    if (walk<NewBlock+NewSize-MIN_MATCH_LEN)
+    {
+      // check for a match
+      uint32 hash1=hasher(walk);
+      hash1 &= (hashsize-1);
+      // now, find the longest match in the hash table. If we find one >MIN_MATCH_LEN, take it
+      for(BlockPtr *b=HashedMatches[hash1];b;b=b->Next)
+      {
+        // find the match length
+        int match_of=b->dataptr-lastmatchend;
+        if ((match_of>-32768) && (match_of<32767))
+        {
+          int max_mlength=min(65535,OldBlock+OldSize-b->dataptr);
+          max_mlength=min(max_mlength,NewBlock+NewSize-walk);
+          int i;
+		  for(i=0;i<max_mlength;i++)
+            if (walk[i]!=b->dataptr[i])
+              break;
+          if ((i>MIN_MATCH_LEN) && (i>longest))
+          {
+            longest=i;
+            longest_block=b;
+            if (longest>ACCEPTABLE_MATCH_LEN)
+              break;
+          }
+        }
+      }
+    }
+    // now, we have a match maybe
+    if (longest_block)
+    {      
+      if (pending_raw_len)                                  // must output
+      {
+        ret=1;
+        CopyPending(pending_raw_len,walk-pending_raw_len,outbuf,Output+OutSize);
+        pending_raw_len=0;
+      }
+      // now, output copy block
+      int match_of=longest_block->dataptr-lastmatchend;
+      int nremaining=OutSize-(outbuf-Output);
+      
+      if (match_of)
+        ret=1;
+//        printf("copy from %x to %x len=%d\n", match_of,outbuf-Output,longest);
+      if (longest>127)
+      {
+        // use really long encoding
+        if (nremaining<5)
+          Fail("diff buff needs increase");
+        *(outbuf++)=00;
+        *(outbuf++)=(longest & 255);
+        *(outbuf++)=((longest>>8) & 255);
+        *(outbuf++)=(match_of & 255);
+        *(outbuf++)=((match_of>>8) & 255);
+        
+      }
+      else
+      {
+        if ((match_of>=-128) && (match_of<128))
+        {
+          if (nremaining<2)
+            Fail("diff buff needs increase");
+          *(outbuf++)=128+longest;
+          *(outbuf++)=(match_of&255);
+        }
+        else
+        {
+          // use long encoding
+          if (nremaining<4)
+            Fail("diff buff needs increase");
+          *(outbuf++)=0x80;          
+          *(outbuf++)=longest;
+          *(outbuf++)=(match_of & 255);
+          *(outbuf++)=((match_of>>8) & 255);
+        }
+      }
+      lastmatchend=longest_block->dataptr+longest;
+      walk+=longest;
+    }
+    else
+    {
+      walk++;
+      pending_raw_len++;
+    }
+  }
+  // now, flush pending raw copy
+  if (pending_raw_len)                                  // must output
+  {
+    ret=1;
+    CopyPending(pending_raw_len,walk-pending_raw_len,outbuf,Output+OutSize);
+    pending_raw_len=0;
+  }
+  delete[] HashedMatches;
+  if (Blocks)
+    delete[] Blocks;
+  DiffListSize=outbuf-Output;
+  return ret;
+}
+
+
+int FindDiffs(uint8 const *NewBlock, uint8 const *OldBlock,
+               int NewSize, int OldSize, int &DiffListSize,uint8 *Output,uint32 OutSize)
+{
+  
+  int ret=0;
+  if (OldSize!=NewSize)
+    ret=1;
+  // first, build the hash table
+  BlockPtr *HashedMatches[65536];
+  memset(HashedMatches,0,sizeof(HashedMatches));
+  BlockPtr *Blocks=0;
+  if (OldSize)
+    Blocks=new BlockPtr[OldSize];
+  BlockPtr *FreeList=Blocks;
+  // now, build the hash table
+  uint8 const *walk=OldBlock;
+  if (OldBlock && OldSize)
+    while(walk<OldBlock+OldSize-MIN_MATCH_LEN)
+    {
+      uint16 hash1=*((uint16 const *) walk)+*((uint16 const *) walk+2);
+      BlockPtr *newnode=FreeList;
+      FreeList++;
+      newnode->dataptr=walk;
+      AddToHead(HashedMatches[hash1],newnode);
+      walk++;
+    }
+  else
+    ret=1;
+  // now, we have the hash table which may be used to search. begin the output step
+  int pending_raw_len=0;
+  walk=NewBlock;
+  uint8 *outbuf=Output;
+  uint8 const *lastmatchend=OldBlock;
+  while(walk<NewBlock+NewSize)
+  {
+    int longest=0;
+    BlockPtr *longest_block=0;
+    if (walk<NewBlock+NewSize-MIN_MATCH_LEN)
+    {
+      // check for a match
+      uint16 hash1=*((uint16 const *) walk)+*((uint16 const *) walk+2);
+      // now, find the longest match in the hash table. If we find one >MIN_MATCH_LEN, take it
+      for(BlockPtr *b=HashedMatches[hash1];b;b=b->Next)
+      {
+        // find the match length
+        int match_of=b->dataptr-lastmatchend;
+        if ((match_of>-32768) && (match_of<32767))
+        {
+          int max_mlength=min(65535,OldBlock+OldSize-b->dataptr);
+          max_mlength=min(max_mlength,NewBlock+NewSize-walk);
+          int i;
+		  for(i=0;i<max_mlength;i++)
+            if (walk[i]!=b->dataptr[i])
+              break;
+          if ((i>MIN_MATCH_LEN) && (i>longest))
+          {
+            longest=i;
+            longest_block=b;
+          }
+        }
+      }
+    }
+    // now, we have a match maybe
+    if (longest_block)
+    {
+      if (pending_raw_len)                                  // must output
+      {
+        ret=1;
+        CopyPending(pending_raw_len,walk-pending_raw_len,outbuf,Output+OutSize);
+        pending_raw_len=0;
+      }
+      // now, output copy block
+      int match_of=longest_block->dataptr-lastmatchend;
+      int nremaining=OutSize-(outbuf-Output);
+      if (match_of)
+        ret=1;
+      if (longest>127)
+      {
+        // use really long encoding
+        if (nremaining<5)
+          Fail("diff buff needs increase");
+        *(outbuf++)=00;
+        *(outbuf++)=(longest & 255);
+        *(outbuf++)=((longest>>8) & 255);
+        *(outbuf++)=(match_of & 255);
+        *(outbuf++)=((match_of>>8) & 255);
+      }
+      else
+      {
+        if ((match_of>=-128) && (match_of<128))
+        {
+          if (nremaining<2)
+            Fail("diff buff needs increase");
+          *(outbuf++)=128+longest;
+          *(outbuf++)=(match_of&255);
+        }
+        else
+        {
+          // use long encoding
+          if (nremaining<4)
+            Fail("diff buff needs increase");
+          *(outbuf++)=0x80;
+          *(outbuf++)=longest;
+          *(outbuf++)=(match_of & 255);
+          *(outbuf++)=((match_of>>8) & 255);
+        }
+      }
+      lastmatchend=longest_block->dataptr+longest;
+      walk+=longest;
+    }
+    else
+    {
+      walk++;
+      pending_raw_len++;
+    }
+  }
+  // now, flush pending raw copy
+  if (pending_raw_len)                                  // must output
+  {
+    ret=1;
+    CopyPending(pending_raw_len,walk-pending_raw_len,outbuf,Output+OutSize);
+    pending_raw_len=0;
+  }
+  if (Blocks)
+    delete[] Blocks;
+  DiffListSize=outbuf-Output;
+  return ret;
+}
+
+
+int FindDiffsLowMemory(uint8 const *NewBlock, uint8 const *OldBlock,
+                        int NewSize, int OldSize, int &DiffListSize,uint8 *Output,uint32 OutSize)
+{
+  
+  int ret=0;
+  if (OldSize!=NewSize)
+    ret=1;
+  uint8 const *old_data_hash[256];
+  memset(old_data_hash,0,sizeof(old_data_hash));
+  int pending_raw_len=0;
+  uint8 const *walk=NewBlock;
+  uint8 const *oldptr=OldBlock;
+  uint8 *outbuf=Output;
+  uint8 const *lastmatchend=OldBlock;
+  while(walk<NewBlock+NewSize)
+  {
+    while( (oldptr-OldBlock<walk-NewBlock+40) && (oldptr-OldBlock<OldSize-MIN_MATCH_LEN))
+    {
+      uint16 hash1=(oldptr[0]+oldptr[1]+oldptr[2]+oldptr[3]) & (NELEMS(old_data_hash)-1);
+      old_data_hash[hash1]=oldptr;
+      oldptr++;
+    }
+    int longest=0;
+    uint8 const *longest_block=0;
+    if (walk<NewBlock+NewSize-MIN_MATCH_LEN)
+    {
+      // check for a match
+      uint16 hash1=(walk[0]+walk[1]+walk[2]+walk[3]) & (NELEMS(old_data_hash)-1);
+      if (old_data_hash[hash1])
+      {
+        int max_bytes_to_compare=min(NewBlock+NewSize-walk,OldBlock+OldSize-old_data_hash[hash1]);
+        int nmatches;
+		for(nmatches=0;nmatches<max_bytes_to_compare;nmatches++)
+          if (walk[nmatches]!=old_data_hash[hash1][nmatches])
+            break;
+        if (nmatches>MIN_MATCH_LEN)
+        {
+          longest_block=old_data_hash[hash1];
+          longest=nmatches;
+        }
+      }
+    }
+    // now, we have a match maybe
+    if (longest_block)
+    {
+      if (pending_raw_len)                                  // must output
+      {
+        ret=1;
+        CopyPending(pending_raw_len,walk-pending_raw_len,outbuf,Output+OutSize);
+        pending_raw_len=0;
+      }
+      // now, output copy block
+      int match_of=longest_block-lastmatchend;
+      int nremaining=OutSize-(outbuf-Output);
+      if (match_of)
+        ret=1;
+      if (longest>127)
+      {
+        // use really long encoding
+        if (nremaining<5)
+          Fail("diff buff needs increase");
+        *(outbuf++)=00;
+        *(outbuf++)=(longest & 255);
+        *(outbuf++)=((longest>>8) & 255);
+        *(outbuf++)=(match_of & 255);
+        *(outbuf++)=((match_of>>8) & 255);
+      }
+      else
+      {
+        if ((match_of>=-128) && (match_of<128))
+        {
+          if (nremaining<2)
+            Fail("diff buff needs increase");
+          *(outbuf++)=128+longest;
+          *(outbuf++)=(match_of&255);
+        }
+        else
+        {
+          // use long encoding
+          if (nremaining<4)
+            Fail("diff buff needs increase");
+          *(outbuf++)=0x80;
+          *(outbuf++)=longest;
+          *(outbuf++)=(match_of & 255);
+          *(outbuf++)=((match_of>>8) & 255);
+        }
+      }
+      lastmatchend=longest_block+longest;
+      walk+=longest;
+    }
+    else
+    {
+      walk++;
+      pending_raw_len++;
+    }
+  }
+  // now, flush pending raw copy
+  if (pending_raw_len)                                  // must output
+  {
+    ret=1;
+    CopyPending(pending_raw_len,walk-pending_raw_len,outbuf,Output+OutSize);
+    pending_raw_len=0;
+  }
+  DiffListSize=outbuf-Output;
+  return ret;
+}
+
+
-- 
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