ddnet/src/engine/shared/huffman.cpp

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/* (c) Magnus Auvinen. See licence.txt in the root of the distribution for more information. */
/* If you are missing that file, acquire a complete release at teeworlds.com. */
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#include "huffman.h"
#include <algorithm>
#include <base/system.h>
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const unsigned CHuffman::ms_aFreqTable[HUFFMAN_MAX_SYMBOLS] = {
1 << 30, 4545, 2657, 431, 1950, 919, 444, 482, 2244, 617, 838, 542, 715, 1814, 304, 240, 754, 212, 647, 186,
283, 131, 146, 166, 543, 164, 167, 136, 179, 859, 363, 113, 157, 154, 204, 108, 137, 180, 202, 176,
872, 404, 168, 134, 151, 111, 113, 109, 120, 126, 129, 100, 41, 20, 16, 22, 18, 18, 17, 19,
16, 37, 13, 21, 362, 166, 99, 78, 95, 88, 81, 70, 83, 284, 91, 187, 77, 68, 52, 68,
59, 66, 61, 638, 71, 157, 50, 46, 69, 43, 11, 24, 13, 19, 10, 12, 12, 20, 14, 9,
20, 20, 10, 10, 15, 15, 12, 12, 7, 19, 15, 14, 13, 18, 35, 19, 17, 14, 8, 5,
15, 17, 9, 15, 14, 18, 8, 10, 2173, 134, 157, 68, 188, 60, 170, 60, 194, 62, 175, 71,
148, 67, 167, 78, 211, 67, 156, 69, 1674, 90, 174, 53, 147, 89, 181, 51, 174, 63, 163, 80,
167, 94, 128, 122, 223, 153, 218, 77, 200, 110, 190, 73, 174, 69, 145, 66, 277, 143, 141, 60,
136, 53, 180, 57, 142, 57, 158, 61, 166, 112, 152, 92, 26, 22, 21, 28, 20, 26, 30, 21,
32, 27, 20, 17, 23, 21, 30, 22, 22, 21, 27, 25, 17, 27, 23, 18, 39, 26, 15, 21,
12, 18, 18, 27, 20, 18, 15, 19, 11, 17, 33, 12, 18, 15, 19, 18, 16, 26, 17, 18,
9, 10, 25, 22, 22, 17, 20, 16, 6, 16, 15, 20, 14, 18, 24, 335, 1517};
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struct CHuffmanConstructNode
{
unsigned short m_NodeId;
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int m_Frequency;
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};
bool CompareNodesByFrequencyDesc(const CHuffmanConstructNode *pNode1, const CHuffmanConstructNode *pNode2)
{
return pNode2->m_Frequency < pNode1->m_Frequency;
}
void CHuffman::Setbits_r(CNode *pNode, int Bits, unsigned Depth)
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{
if(pNode->m_aLeafs[1] != 0xffff)
Setbits_r(&m_aNodes[pNode->m_aLeafs[1]], Bits | (1 << Depth), Depth + 1);
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if(pNode->m_aLeafs[0] != 0xffff)
Setbits_r(&m_aNodes[pNode->m_aLeafs[0]], Bits, Depth + 1);
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if(pNode->m_NumBits)
{
pNode->m_Bits = Bits;
pNode->m_NumBits = Depth;
}
}
void CHuffman::ConstructTree(const unsigned *pFrequencies)
{
CHuffmanConstructNode aNodesLeftStorage[HUFFMAN_MAX_SYMBOLS];
CHuffmanConstructNode *apNodesLeft[HUFFMAN_MAX_SYMBOLS];
int NumNodesLeft = HUFFMAN_MAX_SYMBOLS;
// add the symbols
for(int i = 0; i < HUFFMAN_MAX_SYMBOLS; i++)
{
m_aNodes[i].m_NumBits = 0xFFFFFFFF;
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m_aNodes[i].m_Symbol = i;
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m_aNodes[i].m_aLeafs[0] = 0xffff;
m_aNodes[i].m_aLeafs[1] = 0xffff;
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if(i == HUFFMAN_EOF_SYMBOL)
aNodesLeftStorage[i].m_Frequency = 1;
else
aNodesLeftStorage[i].m_Frequency = pFrequencies[i];
aNodesLeftStorage[i].m_NodeId = i;
apNodesLeft[i] = &aNodesLeftStorage[i];
}
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m_NumNodes = HUFFMAN_MAX_SYMBOLS;
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// construct the table
while(NumNodesLeft > 1)
{
std::stable_sort(apNodesLeft, apNodesLeft + NumNodesLeft, CompareNodesByFrequencyDesc);
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m_aNodes[m_NumNodes].m_NumBits = 0;
m_aNodes[m_NumNodes].m_aLeafs[0] = apNodesLeft[NumNodesLeft - 1]->m_NodeId;
m_aNodes[m_NumNodes].m_aLeafs[1] = apNodesLeft[NumNodesLeft - 2]->m_NodeId;
apNodesLeft[NumNodesLeft - 2]->m_NodeId = m_NumNodes;
apNodesLeft[NumNodesLeft - 2]->m_Frequency = apNodesLeft[NumNodesLeft - 1]->m_Frequency + apNodesLeft[NumNodesLeft - 2]->m_Frequency;
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m_NumNodes++;
NumNodesLeft--;
}
// set start node
m_pStartNode = &m_aNodes[m_NumNodes - 1];
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// build symbol bits
Setbits_r(m_pStartNode, 0, 0);
}
void CHuffman::Init(const unsigned *pFrequencies)
{
// make sure to cleanout every thing
mem_zero(m_aNodes, sizeof(m_aNodes));
mem_zero(m_apDecodeLut, sizeof(m_apDecodeLut));
m_pStartNode = 0x0;
m_NumNodes = 0;
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// construct the tree
ConstructTree(pFrequencies);
// build decode LUT
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for(int i = 0; i < HUFFMAN_LUTSIZE; i++)
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{
unsigned Bits = i;
int k;
CNode *pNode = m_pStartNode;
for(k = 0; k < HUFFMAN_LUTBITS; k++)
{
pNode = &m_aNodes[pNode->m_aLeafs[Bits & 1]];
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Bits >>= 1;
if(!pNode)
break;
if(pNode->m_NumBits)
{
m_apDecodeLut[i] = pNode;
break;
}
}
if(k == HUFFMAN_LUTBITS)
m_apDecodeLut[i] = pNode;
}
}
//***************************************************************
int CHuffman::Compress(const void *pInput, int InputSize, void *pOutput, int OutputSize) const
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{
// this macro loads a symbol for a byte into bits and bitcount
#define HUFFMAN_MACRO_LOADSYMBOL(Sym) \
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do \
{ \
Bits |= m_aNodes[Sym].m_Bits << Bitcount; \
Bitcount += m_aNodes[Sym].m_NumBits; \
} while(0)
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// this macro writes the symbol stored in bits and bitcount to the dst pointer
#define HUFFMAN_MACRO_WRITE() \
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do \
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{ \
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while(Bitcount >= 8) \
{ \
*pDst++ = (unsigned char)(Bits & 0xff); \
if(pDst == pDstEnd) \
return -1; \
Bits >>= 8; \
Bitcount -= 8; \
} \
} while(0)
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// setup buffer pointers
const unsigned char *pSrc = (const unsigned char *)pInput;
const unsigned char *pSrcEnd = pSrc + InputSize;
unsigned char *pDst = (unsigned char *)pOutput;
unsigned char *pDstEnd = pDst + OutputSize;
// symbol variables
unsigned Bits = 0;
unsigned Bitcount = 0;
// make sure that we have data that we want to compress
if(InputSize)
{
// {A} load the first symbol
int Symbol = *pSrc++;
while(pSrc != pSrcEnd)
{
// {B} load the symbol
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HUFFMAN_MACRO_LOADSYMBOL(Symbol);
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// {C} fetch next symbol, this is done here because it will reduce dependency in the code
Symbol = *pSrc++;
// {B} write the symbol loaded at
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HUFFMAN_MACRO_WRITE();
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}
// write the last symbol loaded from {C} or {A} in the case of only 1 byte input buffer
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HUFFMAN_MACRO_LOADSYMBOL(Symbol);
HUFFMAN_MACRO_WRITE();
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}
// write EOF symbol
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HUFFMAN_MACRO_LOADSYMBOL(HUFFMAN_EOF_SYMBOL);
HUFFMAN_MACRO_WRITE();
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// write out the last bits
*pDst++ = Bits;
// return the size of the output
return (int)(pDst - (const unsigned char *)pOutput);
// remove macros
#undef HUFFMAN_MACRO_LOADSYMBOL
#undef HUFFMAN_MACRO_WRITE
}
//***************************************************************
int CHuffman::Decompress(const void *pInput, int InputSize, void *pOutput, int OutputSize) const
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{
// setup buffer pointers
unsigned char *pDst = (unsigned char *)pOutput;
unsigned char *pSrc = (unsigned char *)pInput;
unsigned char *pDstEnd = pDst + OutputSize;
unsigned char *pSrcEnd = pSrc + InputSize;
unsigned Bits = 0;
unsigned Bitcount = 0;
const CNode *pEof = &m_aNodes[HUFFMAN_EOF_SYMBOL];
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while(true)
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{
// {A} try to load a node now, this will reduce dependency at location {D}
const CNode *pNode = 0;
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if(Bitcount >= HUFFMAN_LUTBITS)
pNode = m_apDecodeLut[Bits & HUFFMAN_LUTMASK];
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// {B} fill with new bits
while(Bitcount < 24 && pSrc != pSrcEnd)
{
Bits |= (*pSrc++) << Bitcount;
Bitcount += 8;
}
// {C} load symbol now if we didn't that earlier at location {A}
if(!pNode)
pNode = m_apDecodeLut[Bits & HUFFMAN_LUTMASK];
if(!pNode)
return -1;
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// {D} check if we hit a symbol already
if(pNode->m_NumBits)
{
// remove the bits for that symbol
Bits >>= pNode->m_NumBits;
Bitcount -= pNode->m_NumBits;
}
else
{
// remove the bits that the lut checked up for us
Bits >>= HUFFMAN_LUTBITS;
Bitcount -= HUFFMAN_LUTBITS;
// walk the tree bit by bit
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while(true)
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{
// traverse tree
pNode = &m_aNodes[pNode->m_aLeafs[Bits & 1]];
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// remove bit
Bitcount--;
Bits >>= 1;
// check if we hit a symbol
if(pNode->m_NumBits)
break;
// no more bits, decoding error
if(Bitcount == 0)
return -1;
}
}
// check for eof
if(pNode == pEof)
break;
// output character
if(pDst == pDstEnd)
return -1;
*pDst++ = pNode->m_Symbol;
}
// return the size of the decompressed buffer
return (int)(pDst - (const unsigned char *)pOutput);
}