4.44 beta

C/Compress/Branch/BranchX86.c

@@ -0,0 +1,101 @@
+/* BranchX86.c */
+
+#include "BranchX86.h"
+
+/*
+static int inline Test86MSByte(Byte b)
+{
+  return (b == 0 || b == 0xFF);
+}
+*/
+#define Test86MSByte(b) ((b) == 0 || (b) == 0xFF)
+
+const int kMaskToAllowedStatus[8] = {1, 1, 1, 0, 1, 0, 0, 0};
+const Byte kMaskToBitNumber[8] = {0, 1, 2, 2, 3, 3, 3, 3};
+
+/*
+void x86_Convert_Init(UInt32 *prevMask, UInt32 *prevPos)
+{
+  *prevMask = 0;
+  *prevPos = (UInt32)(-5);
+}
+*/
+
+UInt32 x86_Convert(Byte *buffer, UInt32 endPos, UInt32 nowPos, 
+    UInt32 *prevMask, UInt32 *prevPos, int encoding)
+{
+  UInt32 bufferPos = 0;
+  UInt32 limit;
+
+  if (endPos < 5)
+    return 0;
+  
+  if (nowPos - *prevPos > 5)
+    *prevPos = nowPos - 5;
+  
+  limit = endPos - 5;
+  while(bufferPos <= limit)
+  {
+    Byte b = buffer[bufferPos];
+    UInt32 offset;
+    if (b != 0xE8 && b != 0xE9)
+    {
+      bufferPos++;
+      continue;
+    }
+    offset = (nowPos + bufferPos - *prevPos);
+    *prevPos = (nowPos + bufferPos);
+    if (offset > 5)
+      *prevMask = 0;
+    else
+    {
+      UInt32 i;
+      for (i = 0; i < offset; i++)
+      {
+        *prevMask &= 0x77;
+        *prevMask <<= 1;
+      }
+    }
+    b = buffer[bufferPos + 4];
+    if (Test86MSByte(b) && kMaskToAllowedStatus[(*prevMask >> 1) & 0x7] && 
+      (*prevMask >> 1) < 0x10)
+    {
+      UInt32 src = 
+        ((UInt32)(b) << 24) |
+        ((UInt32)(buffer[bufferPos + 3]) << 16) |
+        ((UInt32)(buffer[bufferPos + 2]) << 8) |
+        (buffer[bufferPos + 1]);
+      
+      UInt32 dest;
+      for (;;)
+      {
+        UInt32 index;
+        if (encoding)
+          dest = (nowPos + bufferPos + 5) + src;
+        else
+          dest = src - (nowPos + bufferPos + 5);
+        if (*prevMask == 0)
+          break;
+        index = kMaskToBitNumber[*prevMask >> 1];
+        b = (Byte)(dest >> (24 - index * 8));
+        if (!Test86MSByte(b))
+          break;
+        src = dest ^ ((1 << (32 - index * 8)) - 1);
+      }
+      buffer[bufferPos + 4] = (Byte)(~(((dest >> 24) & 1) - 1));
+      buffer[bufferPos + 3] = (Byte)(dest >> 16);
+      buffer[bufferPos + 2] = (Byte)(dest >> 8);
+      buffer[bufferPos + 1] = (Byte)dest;
+      bufferPos += 5;
+      *prevMask = 0;
+    }
+    else
+    {
+      bufferPos++;
+      *prevMask |= 1;
+      if (Test86MSByte(b))
+        *prevMask |= 0x10;
+    }
+  }
+  return bufferPos;
+}