69 lines
1.7 KiB
C++
69 lines
1.7 KiB
C++
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#ifndef _RAR_GETBITS_
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#define _RAR_GETBITS_
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class BitInput
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{
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public:
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enum BufferSize {MAX_SIZE=0x8000}; // Size of input buffer.
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int InAddr; // Curent byte position in the buffer.
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int InBit; // Current bit position in the current byte.
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bool ExternalBuffer;
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public:
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BitInput(bool AllocBuffer);
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~BitInput();
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byte *InBuf; // Dynamically allocated input buffer.
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void InitBitInput()
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{
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InAddr=InBit=0;
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}
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// Move forward by 'Bits' bits.
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void addbits(uint Bits)
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{
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Bits+=InBit;
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InAddr+=Bits>>3;
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InBit=Bits&7;
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}
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// Return 16 bits from current position in the buffer.
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// Bit at (InAddr,InBit) has the highest position in returning data.
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uint getbits()
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{
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uint BitField=(uint)InBuf[InAddr] << 16;
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BitField|=(uint)InBuf[InAddr+1] << 8;
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BitField|=(uint)InBuf[InAddr+2];
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BitField >>= (8-InBit);
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return BitField & 0xffff;
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}
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// Return 32 bits from current position in the buffer.
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// Bit at (InAddr,InBit) has the highest position in returning data.
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uint getbits32()
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{
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uint BitField=(uint)InBuf[InAddr] << 24;
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BitField|=(uint)InBuf[InAddr+1] << 16;
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BitField|=(uint)InBuf[InAddr+2] << 8;
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BitField|=(uint)InBuf[InAddr+3];
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BitField <<= InBit;
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BitField|=(uint)InBuf[InAddr+4] >> (8-InBit);
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return BitField & 0xffffffff;
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}
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void faddbits(uint Bits);
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uint fgetbits();
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// Check if buffer has enough space for IncPtr bytes. Returns 'true'
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// if buffer will be overflown.
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bool Overflow(uint IncPtr)
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{
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return InAddr+IncPtr>=MAX_SIZE;
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}
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void SetExternalBuffer(byte *Buf);
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};
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#endif
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