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/* huffman compresion based on teeworlds/ddnet huffman */
/*{ https://github.com/teeworlds/teeworlds/blob/master/src/engine/shared/huffman.cpp } */
#include "../inc/huffman.h"
#define HUFF_MAX_NODES (HUFF_MAX_SYMBOLS) * 2 - 1
#define HUFF_MAX_SYMBOLS HUFF_EOF_SYMBOL + 1
#define HUFF_EOF_SYMBOL 256
typedef struct
{
unsigned short symbol;
unsigned int bits;
unsigned int numbits;
unsigned short left, right;
} huffnode;
typedef struct
{
unsigned short symbol;
int freq;
} constructnode;
const unsigned int freqtable[HUFF_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};
huffnode *rootnode;
huffnode nodes[HUFF_MAX_NODES];
int numnodes;
void merge(constructnode **arr, int left, int middle, int right)
{
int i, j, k;
int larrlen = middle - left + 1;
int rarrlen = right - middle;
constructnode *larr[larrlen], *rarr[rarrlen];
for (i = 0; i < larrlen; i++)
larr[i] = arr[left + i];
for (j = 0; j < rarrlen; j++)
rarr[j] = arr[middle + 1 + j];
i = j = 0;
k = left;
while (i < larrlen && j < rarrlen)
{
if (larr[i]->freq >= rarr[j]->freq)
{
arr[k] = larr[i];
i++;
}
else
{
arr[k] = rarr[j];
j++;
}
k++;
}
while (i < larrlen)
{
arr[k] = larr[i];
i++;
k++;
}
while (j < rarrlen)
{
arr[k] = rarr[j];
j++;
k++;
}
}
void mergesort(constructnode **arr, int left, int right)
{
if (left < right)
{
int middle = left + (right - left) / 2;
mergesort(arr, left, middle);
mergesort(arr, middle + 1, right);
merge(arr, left, middle, right);
}
}
void setbits(huffnode *node, int bits, unsigned int depth)
{
if (node->right != 0xffff)
setbits(&nodes[node->right], bits | (1 << depth), depth + 1);
if (node->left != 0xffff)
setbits(&nodes[node->left], bits, depth + 1);
if (node->numbits)
{
node->bits = bits;
node->numbits = depth;
}
}
void constructhufftree(const unsigned int *frequencies)
{
constructnode nodesdata[HUFF_MAX_SYMBOLS];
constructnode *sortednodes[HUFF_MAX_SYMBOLS];
for (int i = 0; i < HUFF_MAX_SYMBOLS; i++)
{
nodes[i].numbits = 0xffffffff;
nodes[i].symbol = i;
nodes[i].left = 0xffff;
nodes[i].right = 0xffff;
if (i == HUFF_EOF_SYMBOL)
nodesdata[i].freq = 1;
else
nodesdata[i].freq = frequencies[i];
nodesdata[i].symbol = i;
sortednodes[i] = &nodesdata[i];
}
numnodes = HUFF_MAX_SYMBOLS;
for (int numnodesleft = HUFF_MAX_SYMBOLS; numnodesleft > 1; numnodesleft--)
{
mergesort(sortednodes, 0, numnodesleft - 1);
nodes[numnodes].numbits = 0;
nodes[numnodes].left = sortednodes[numnodesleft - 1]->symbol;
nodes[numnodes].right = sortednodes[numnodesleft - 2]->symbol;
sortednodes[numnodesleft - 2]->symbol = numnodes;
sortednodes[numnodesleft - 2]->freq = sortednodes[numnodesleft - 1]->freq + sortednodes[numnodesleft - 2]->freq;
numnodes++;
}
rootnode = &nodes[numnodes - 1];
setbits(rootnode, 0, 0);
}
void inithuff(const unsigned int *frequencies)
{
if (!frequencies)
constructhufftree(freqtable);
else
constructhufftree(frequencies);
}
int compresshuff(const char *inputbuff, int inputsize, char *outputbuff, int outputsize)
{
int outputlen = 0;
char bits = 0;
char numbits = 0;
unsigned short symbol;
for (int y = 0; y < inputsize; y++)
{
symbol = (unsigned char)*(inputbuff + y);
appendeof:
for (unsigned int i = 0; i < nodes[symbol].numbits; i++)
{
char bit = (nodes[symbol].bits >> i) & 1;
bits |= (bit << numbits);
numbits++;
if (numbits == 8)
{
if (outputlen >= outputsize - 1)
return -1;
outputbuff[outputlen] = bits;
outputlen++;
numbits = 0;
bits = 0;
}
}
}
if (symbol != HUFF_EOF_SYMBOL)
{
symbol = HUFF_EOF_SYMBOL;
goto appendeof;
}
outputbuff[outputlen] = bits;
outputlen++;
return outputlen;
}
int decompresshuff(const char *inputbuff, int inputsize, char *outputbuff, int outputsize)
{
int inputoff = 0;
int outputlen = 0;
int bits = 0;
int numbits = 0;
huffnode *node;
while (1)
{
while (numbits < 24 && inputoff != inputsize)
{
bits |= (unsigned char)inputbuff[inputoff++] << numbits;
numbits += 8;
}
node = rootnode;
while (1)
{
if (bits & 1)
node = &nodes[node->right];
else
node = &nodes[node->left];
bits >>= 1;
numbits--;
if (node->numbits)
break;
if (numbits == 0)
return -1;
}
if (node->symbol == HUFF_EOF_SYMBOL)
return outputlen;
if (outputlen == outputsize)
return -1;
outputbuff[outputlen++] = node->symbol;
}
}
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