ref: bea7b7bf8ccbc2bc41906517079e76fcfb31cb5a
dir: /code/qcommon/huffman.c/
/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.
This file is part of Quake III Arena source code.
Quake III Arena source code is free software; you can redistribute it
and/or modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the License,
or (at your option) any later version.
Quake III Arena source code is distributed in the hope that it will be
useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Foobar; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
===========================================================================
*/
/* This is based on the Adaptive Huffman algorithm described in Sayood's Data
* Compression book. The ranks are not actually stored, but implicitly defined
* by the location of a node within a doubly-linked list */
#include "../game/q_shared.h"
#include "qcommon.h"
static int bloc = 0;
void Huff_putBit( int bit, byte *fout, int *offset) {
bloc = *offset;
if ((bloc&7) == 0) {
fout[(bloc>>3)] = 0;
}
fout[(bloc>>3)] |= bit << (bloc&7);
bloc++;
*offset = bloc;
}
int Huff_getBit( byte *fin, int *offset) {
int t;
bloc = *offset;
t = (fin[(bloc>>3)] >> (bloc&7)) & 0x1;
bloc++;
*offset = bloc;
return t;
}
/* Add a bit to the output file (buffered) */
static void add_bit (char bit, byte *fout) {
if ((bloc&7) == 0) {
fout[(bloc>>3)] = 0;
}
fout[(bloc>>3)] |= bit << (bloc&7);
bloc++;
}
/* Receive one bit from the input file (buffered) */
static int get_bit (byte *fin) {
int t;
t = (fin[(bloc>>3)] >> (bloc&7)) & 0x1;
bloc++;
return t;
}
static node_t **get_ppnode(huff_t* huff) {
node_t **tppnode;
if (!huff->freelist) {
return &(huff->nodePtrs[huff->blocPtrs++]);
} else {
tppnode = huff->freelist;
huff->freelist = (node_t **)*tppnode;
return tppnode;
}
}
static void free_ppnode(huff_t* huff, node_t **ppnode) {
*ppnode = (node_t *)huff->freelist;
huff->freelist = ppnode;
}
/* Swap the location of these two nodes in the tree */
static void swap (huff_t* huff, node_t *node1, node_t *node2) {
node_t *par1, *par2;
par1 = node1->parent;
par2 = node2->parent;
if (par1) {
if (par1->left == node1) {
par1->left = node2;
} else {
par1->right = node2;
}
} else {
huff->tree = node2;
}
if (par2) {
if (par2->left == node2) {
par2->left = node1;
} else {
par2->right = node1;
}
} else {
huff->tree = node1;
}
node1->parent = par2;
node2->parent = par1;
}
/* Swap these two nodes in the linked list (update ranks) */
static void swaplist(node_t *node1, node_t *node2) {
node_t *par1;
par1 = node1->next;
node1->next = node2->next;
node2->next = par1;
par1 = node1->prev;
node1->prev = node2->prev;
node2->prev = par1;
if (node1->next == node1) {
node1->next = node2;
}
if (node2->next == node2) {
node2->next = node1;
}
if (node1->next) {
node1->next->prev = node1;
}
if (node2->next) {
node2->next->prev = node2;
}
if (node1->prev) {
node1->prev->next = node1;
}
if (node2->prev) {
node2->prev->next = node2;
}
}
/* Do the increments */
static void increment(huff_t* huff, node_t *node) {
node_t *lnode;
if (!node) {
return;
}
if (node->next != NULL && node->next->weight == node->weight) {
lnode = *node->head;
if (lnode != node->parent) {
swap(huff, lnode, node);
}
swaplist(lnode, node);
}
if (node->prev && node->prev->weight == node->weight) {
*node->head = node->prev;
} else {
*node->head = NULL;
free_ppnode(huff, node->head);
}
node->weight++;
if (node->next && node->next->weight == node->weight) {
node->head = node->next->head;
} else {
node->head = get_ppnode(huff);
*node->head = node;
}
if (node->parent) {
increment(huff, node->parent);
if (node->prev == node->parent) {
swaplist(node, node->parent);
if (*node->head == node) {
*node->head = node->parent;
}
}
}
}
void Huff_addRef(huff_t* huff, byte ch) {
node_t *tnode, *tnode2;
if (huff->loc[ch] == NULL) { /* if this is the first transmission of this node */
tnode = &(huff->nodeList[huff->blocNode++]);
tnode2 = &(huff->nodeList[huff->blocNode++]);
tnode2->symbol = INTERNAL_NODE;
tnode2->weight = 1;
tnode2->next = huff->lhead->next;
if (huff->lhead->next) {
huff->lhead->next->prev = tnode2;
if (huff->lhead->next->weight == 1) {
tnode2->head = huff->lhead->next->head;
} else {
tnode2->head = get_ppnode(huff);
*tnode2->head = tnode2;
}
} else {
tnode2->head = get_ppnode(huff);
*tnode2->head = tnode2;
}
huff->lhead->next = tnode2;
tnode2->prev = huff->lhead;
tnode->symbol = ch;
tnode->weight = 1;
tnode->next = huff->lhead->next;
if (huff->lhead->next) {
huff->lhead->next->prev = tnode;
if (huff->lhead->next->weight == 1) {
tnode->head = huff->lhead->next->head;
} else {
/* this should never happen */
tnode->head = get_ppnode(huff);
*tnode->head = tnode2;
}
} else {
/* this should never happen */
tnode->head = get_ppnode(huff);
*tnode->head = tnode;
}
huff->lhead->next = tnode;
tnode->prev = huff->lhead;
tnode->left = tnode->right = NULL;
if (huff->lhead->parent) {
if (huff->lhead->parent->left == huff->lhead) { /* lhead is guaranteed to by the NYT */
huff->lhead->parent->left = tnode2;
} else {
huff->lhead->parent->right = tnode2;
}
} else {
huff->tree = tnode2;
}
tnode2->right = tnode;
tnode2->left = huff->lhead;
tnode2->parent = huff->lhead->parent;
huff->lhead->parent = tnode->parent = tnode2;
huff->loc[ch] = tnode;
increment(huff, tnode2->parent);
} else {
increment(huff, huff->loc[ch]);
}
}
/* Get a symbol */
int Huff_Receive (node_t *node, int *ch, byte *fin) {
while (node && node->symbol == INTERNAL_NODE) {
if (get_bit(fin)) {
node = node->right;
} else {
node = node->left;
}
}
if (!node) {
return 0;
// Com_Error(ERR_DROP, "Illegal tree!\n");
}
return (*ch = node->symbol);
}
/* Get a symbol */
void Huff_offsetReceive (node_t *node, int *ch, byte *fin, int *offset) {
bloc = *offset;
while (node && node->symbol == INTERNAL_NODE) {
if (get_bit(fin)) {
node = node->right;
} else {
node = node->left;
}
}
if (!node) {
*ch = 0;
return;
// Com_Error(ERR_DROP, "Illegal tree!\n");
}
*ch = node->symbol;
*offset = bloc;
}
/* Send the prefix code for this node */
static void send(node_t *node, node_t *child, byte *fout) {
if (node->parent) {
send(node->parent, node, fout);
}
if (child) {
if (node->right == child) {
add_bit(1, fout);
} else {
add_bit(0, fout);
}
}
}
/* Send a symbol */
void Huff_transmit (huff_t *huff, int ch, byte *fout) {
int i;
if (huff->loc[ch] == NULL) {
/* node_t hasn't been transmitted, send a NYT, then the symbol */
Huff_transmit(huff, NYT, fout);
for (i = 7; i >= 0; i--) {
add_bit((char)((ch >> i) & 0x1), fout);
}
} else {
send(huff->loc[ch], NULL, fout);
}
}
void Huff_offsetTransmit (huff_t *huff, int ch, byte *fout, int *offset) {
bloc = *offset;
send(huff->loc[ch], NULL, fout);
*offset = bloc;
}
void Huff_Decompress(msg_t *mbuf, int offset) {
int ch, cch, i, j, size;
byte seq[65536];
byte* buffer;
huff_t huff;
size = mbuf->cursize - offset;
buffer = mbuf->data + offset;
if ( size <= 0 ) {
return;
}
Com_Memset(&huff, 0, sizeof(huff_t));
// Initialize the tree & list with the NYT node
huff.tree = huff.lhead = huff.ltail = huff.loc[NYT] = &(huff.nodeList[huff.blocNode++]);
huff.tree->symbol = NYT;
huff.tree->weight = 0;
huff.lhead->next = huff.lhead->prev = NULL;
huff.tree->parent = huff.tree->left = huff.tree->right = NULL;
cch = buffer[0]*256 + buffer[1];
// don't overflow with bad messages
if ( cch > mbuf->maxsize - offset ) {
cch = mbuf->maxsize - offset;
}
bloc = 16;
for ( j = 0; j < cch; j++ ) {
ch = 0;
// don't overflow reading from the messages
// FIXME: would it be better to have a overflow check in get_bit ?
if ( (bloc >> 3) > size ) {
seq[j] = 0;
break;
}
Huff_Receive(huff.tree, &ch, buffer); /* Get a character */
if ( ch == NYT ) { /* We got a NYT, get the symbol associated with it */
ch = 0;
for ( i = 0; i < 8; i++ ) {
ch = (ch<<1) + get_bit(buffer);
}
}
seq[j] = ch; /* Write symbol */
Huff_addRef(&huff, (byte)ch); /* Increment node */
}
mbuf->cursize = cch + offset;
Com_Memcpy(mbuf->data + offset, seq, cch);
}
extern int oldsize;
void Huff_Compress(msg_t *mbuf, int offset) {
int i, ch, size;
byte seq[65536];
byte* buffer;
huff_t huff;
size = mbuf->cursize - offset;
buffer = mbuf->data+ + offset;
if (size<=0) {
return;
}
Com_Memset(&huff, 0, sizeof(huff_t));
// Add the NYT (not yet transmitted) node into the tree/list */
huff.tree = huff.lhead = huff.loc[NYT] = &(huff.nodeList[huff.blocNode++]);
huff.tree->symbol = NYT;
huff.tree->weight = 0;
huff.lhead->next = huff.lhead->prev = NULL;
huff.tree->parent = huff.tree->left = huff.tree->right = NULL;
huff.loc[NYT] = huff.tree;
seq[0] = (size>>8);
seq[1] = size&0xff;
bloc = 16;
for (i=0; i<size; i++ ) {
ch = buffer[i];
Huff_transmit(&huff, ch, seq); /* Transmit symbol */
Huff_addRef(&huff, (byte)ch); /* Do update */
}
bloc += 8; // next byte
mbuf->cursize = (bloc>>3) + offset;
Com_Memcpy(mbuf->data+offset, seq, (bloc>>3));
}
void Huff_Init(huffman_t *huff) {
Com_Memset(&huff->compressor, 0, sizeof(huff_t));
Com_Memset(&huff->decompressor, 0, sizeof(huff_t));
// Initialize the tree & list with the NYT node
huff->decompressor.tree = huff->decompressor.lhead = huff->decompressor.ltail = huff->decompressor.loc[NYT] = &(huff->decompressor.nodeList[huff->decompressor.blocNode++]);
huff->decompressor.tree->symbol = NYT;
huff->decompressor.tree->weight = 0;
huff->decompressor.lhead->next = huff->decompressor.lhead->prev = NULL;
huff->decompressor.tree->parent = huff->decompressor.tree->left = huff->decompressor.tree->right = NULL;
// Add the NYT (not yet transmitted) node into the tree/list */
huff->compressor.tree = huff->compressor.lhead = huff->compressor.loc[NYT] = &(huff->compressor.nodeList[huff->compressor.blocNode++]);
huff->compressor.tree->symbol = NYT;
huff->compressor.tree->weight = 0;
huff->compressor.lhead->next = huff->compressor.lhead->prev = NULL;
huff->compressor.tree->parent = huff->compressor.tree->left = huff->compressor.tree->right = NULL;
huff->compressor.loc[NYT] = huff->compressor.tree;
}