engine/core/bitStream.h

//-----------------------------------------------------------------------------
// V12 Engine
// 
// Copyright (c) 2001 GarageGames.Com
// Portions Copyright (c) 2001 by Sierra Online, Inc.
//-----------------------------------------------------------------------------

#ifndef _BITSTREAM_H_
#define _BITSTREAM_H_

//Includes
#ifndef _PLATFORM_H_
#include "Platform/platform.h"
#endif
#ifndef _STREAM_H_
#include "Core/stream.h"
#endif

//-------------------------------------- Some caveats when using this class:
//                                        - Get/setPosition semantics are changed
//                                         to indicate bit position rather than
//                                         byte position.
//

class Point3F;
class MatrixF;
class HuffmanProcessor;

class BitStream : public Stream
{
protected:
   U8 *dataPtr;
   S32  bitNum;
   S32  bufSize;
   bool error;
   S32  maxReadBitNum;
   S32  maxWriteBitNum;
   char *stringBuffer;

   friend class HuffmanProcessor;
public:
   static BitStream *getPacketStream(U32 writeSize = 0);
   static void sendPacketStream(const NetAddress *addr);

   void setBuffer(void *bufPtr, S32 bufSize, S32 maxSize = 0);
   U8*  getBuffer() { return dataPtr; }
   U8*  getBytePtr();
   
   U32 getReadByteSize();

   S32  getCurPos() const;
   void setCurPos(const U32);

   BitStream(void *bufPtr, S32 bufSize, S32 maxWriteSize = -1) { setBuffer(bufPtr, bufSize,maxWriteSize); stringBuffer = NULL; }
   void clear();
   
   void setStringBuffer(char buffer[256]);
   void writeInt(S32 value, S32 bitCount);
   S32  readInt(S32 bitCount);

   void writeSignedInt(S32 value, S32 bitCount);
   S32  readSignedInt(S32 bitCount);

   void writeRangedU32(U32 value, U32 rangeStart, U32 rangeEnd);
   U32  readRangedU32(U32 rangeStart, U32 rangeEnd);

   // read and write floats... floats are 0 to 1 inclusive, signed floats are -1 to 1 inclusive

   F32  readFloat(S32 bitCount);
   F32  readSignedFloat(S32 bitCount);

   void writeFloat(F32 f, S32 bitCount);
   void writeSignedFloat(F32 f, S32 bitCount);

   // writes a normalized vector
   void writeNormalVector(const Point3F& vec, S32 bitCount);
   void readNormalVector(Point3F *vec, S32 bitCount);

   // Uses the above method to reduce the precision of a normal vector so the server can
   //  determine exactly what is on the client.  (Pre-dumbing the vector before sending
   //  to the client can result in precision errors...)
   static Point3F dumbDownNormal(const Point3F& vec, S32 bitCount);   


   // writes a normalized vector using alternate method
   void writeNormalVector(const Point3F& vec, S32 angleBitCount, S32 zBitCount);
   void readNormalVector(Point3F *vec, S32 angleBitCount, S32 zBitCount);
   
   // writes an affine transform (full precision version)
   void writeAffineTransform(const MatrixF&);
   void readAffineTransform(MatrixF*);

   void writeBits(S32 bitCount, const void *bitPtr);
   void readBits(S32 bitCount, void *bitPtr);
   bool writeFlag(bool val);
   bool readFlag();

   void setBit(S32 bitCount, bool set);
   bool testBit(S32 bitCount);

   bool isFull() { return bitNum > (bufSize << 3); }
   bool isValid() { return !error; }

   bool _read (const U32 size,void* d);
   bool _write(const U32 size,const void* d);

   void readString(char stringBuf[256]);
   void writeString(const char *stringBuf, S32 maxLen=255);

   bool hasCapability(const Capability) const { return true; }
   U32  getPosition() const;
   bool setPosition(const U32 in_newPosition);
   U32  getStreamSize();
};

class ResizeBitStream : public BitStream
{
   U32 mMinSpace;
public:
   ResizeBitStream(U32 minSpace = 1500, U32 initialSize = 0);
   void validate();
   ~ResizeBitStream();
};

//------------------------------------------------------------------------------
//-------------------------------------- INLINES
//
inline S32 BitStream::getCurPos() const
{
   return bitNum;
}

inline void BitStream::setCurPos(const U32 in_position)
{
   AssertFatal(in_position < (U32)(bufSize << 3), "Out of range bitposition");
   bitNum = S32(in_position);
}

inline bool BitStream::readFlag()
{
   if(bitNum > maxReadBitNum)
   {
      error = true;
      AssertFatal(false, "Out of range read");
      return false;
   }
   S32 mask = 1 << (bitNum & 0x7);
   bool ret = (*(dataPtr + (bitNum >> 3)) & mask) != 0;
   bitNum++;
   return ret;
}

inline void BitStream::writeRangedU32(U32 value, U32 rangeStart, U32 rangeEnd)
{
   AssertFatal(value >= rangeStart && value <= rangeEnd, "Out of bounds value!");
   AssertFatal(rangeEnd >= rangeStart, "error, end of range less than start");

   U32 rangeSize = rangeEnd - rangeStart + 1;
   U32 rangeBits = getBinLog2(getNextPow2(rangeSize));

   writeInt(S32(value - rangeStart), S32(rangeBits));
}

inline U32 BitStream::readRangedU32(U32 rangeStart, U32 rangeEnd)
{
   AssertFatal(rangeEnd >= rangeStart, "error, end of range less than start");

   U32 rangeSize = rangeEnd - rangeStart + 1;
   U32 rangeBits = getBinLog2(getNextPow2(rangeSize));

   U32 val = U32(readInt(S32(rangeBits)));
   return val + rangeStart;
}

#endif //_BITSTREAM_H_