yeti-codec/golomb.cpp at master · ejensen/yeti-codec · GitHub

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#include "golomb.h"

static void UnsignedGolombEncode(const unsigned int in, BitOutputManager& bitManger)
{
	unsigned int M = 0;
	unsigned int info;
	unsigned int val2 = in + 1;

	while (val2>1) //get the log base 2 of val.
	{
		val2 >>= 1;
		++M;
	}

	info = in - (1<<M) + 1;

	for(unsigned int i = 1; i <= M ; ++i)
	{
		bitManger.OutputBit(0);
	}

	bitManger.OutputBit(1);

	for(unsigned int i = 0 ; i < M; ++i)
	{
		bitManger.OutputBit((info & (1<<i)) != 0);
	}
}

size_t GolombEncode(const unsigned int* in, BYTE* out, size_t length)
{
	BitOutputManager bitManager(out);
	for(unsigned int i = 0; i < length; i++)
	{
		UnsignedGolombEncode(*(in + i), bitManager);
	}

	bitManager.Flush();

	return bitManager.Size();
}

static size_t UnsignedGolombDecode(BitInputManager& bitManger)
{
	unsigned int M = 0;
	unsigned int info = 0;
	bool bit = 0;

	do
	{
		bit = bitManger.InputBit();
		M += !bit;
	}
	while(!bit && M < 64);//terminate if the number is too big

	for(unsigned int i = 0 ; i < M; ++i)
	{
		if(bitManger.InputBit())
		{
			info |= (1<<i);
		}
	}

	return (1<<M) - 1 + info;
}

size_t GolombDecode(const BYTE* in, unsigned int* out, size_t length)
{
	BitInputManager bitManager(in);
	for(size_t i = 0; i < length; i++)
	{
		*(out + i) = UnsignedGolombDecode(bitManager);
	}

	return bitManager.ByteOffset();
}