416 lines
10 KiB
C++
416 lines
10 KiB
C++
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/* This is based on the Adaptive Huffman algorithm described in Sayood's Data
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* Compression book. The ranks are not actually stored, but implicitly defined
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* by the location of a node within a doubly-linked list */
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#include "../game/q_shared.h"
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#include "qcommon.h"
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static int bloc = 0;
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void Huff_putBit( int bit, byte *fout, int *offset) {
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bloc = *offset;
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if ((bloc&7) == 0) {
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fout[(bloc>>3)] = 0;
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}
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fout[(bloc>>3)] |= bit << (bloc&7);
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bloc++;
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*offset = bloc;
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}
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int Huff_getBit( byte *fin, int *offset) {
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int t;
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bloc = *offset;
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t = (fin[(bloc>>3)] >> (bloc&7)) & 0x1;
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bloc++;
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*offset = bloc;
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return t;
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}
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/* Add a bit to the output file (buffered) */
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static void add_bit (char bit, byte *fout) {
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if ((bloc&7) == 0) {
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fout[(bloc>>3)] = 0;
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}
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fout[(bloc>>3)] |= bit << (bloc&7);
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bloc++;
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}
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/* Receive one bit from the input file (buffered) */
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static int get_bit (byte *fin) {
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int t;
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t = (fin[(bloc>>3)] >> (bloc&7)) & 0x1;
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bloc++;
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return t;
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}
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static node_t **get_ppnode(huff_t* huff) {
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node_t **tppnode;
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if (!huff->freelist) {
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return &(huff->nodePtrs[huff->blocPtrs++]);
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} else {
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tppnode = huff->freelist;
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huff->freelist = (node_t **)*tppnode;
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return tppnode;
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}
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}
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static void free_ppnode(huff_t* huff, node_t **ppnode) {
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*ppnode = (node_t *)huff->freelist;
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huff->freelist = ppnode;
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}
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/* Swap the location of these two nodes in the tree */
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static void swap (huff_t* huff, node_t *node1, node_t *node2) {
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node_t *par1, *par2;
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par1 = node1->parent;
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par2 = node2->parent;
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if (par1) {
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if (par1->left == node1) {
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par1->left = node2;
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} else {
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par1->right = node2;
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}
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} else {
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huff->tree = node2;
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}
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if (par2) {
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if (par2->left == node2) {
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par2->left = node1;
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} else {
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par2->right = node1;
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}
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} else {
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huff->tree = node1;
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}
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node1->parent = par2;
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node2->parent = par1;
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}
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/* Swap these two nodes in the linked list (update ranks) */
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static void swaplist(node_t *node1, node_t *node2) {
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node_t *par1;
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par1 = node1->next;
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node1->next = node2->next;
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node2->next = par1;
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par1 = node1->prev;
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node1->prev = node2->prev;
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node2->prev = par1;
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if (node1->next == node1) {
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node1->next = node2;
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}
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if (node2->next == node2) {
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node2->next = node1;
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}
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if (node1->next) {
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node1->next->prev = node1;
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}
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if (node2->next) {
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node2->next->prev = node2;
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}
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if (node1->prev) {
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node1->prev->next = node1;
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}
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if (node2->prev) {
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node2->prev->next = node2;
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}
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}
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/* Do the increments */
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static void increment(huff_t* huff, node_t *node) {
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node_t *lnode;
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if (!node) {
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return;
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}
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if (node->next != NULL && node->next->weight == node->weight) {
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lnode = *node->head;
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if (lnode != node->parent) {
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swap(huff, lnode, node);
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}
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swaplist(lnode, node);
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}
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if (node->prev && node->prev->weight == node->weight) {
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*node->head = node->prev;
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} else {
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*node->head = NULL;
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free_ppnode(huff, node->head);
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}
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node->weight++;
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if (node->next && node->next->weight == node->weight) {
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node->head = node->next->head;
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} else {
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node->head = get_ppnode(huff);
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*node->head = node;
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}
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if (node->parent) {
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increment(huff, node->parent);
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if (node->prev == node->parent) {
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swaplist(node, node->parent);
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if (*node->head == node) {
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*node->head = node->parent;
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}
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}
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}
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}
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void Huff_addRef(huff_t* huff, byte ch) {
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node_t *tnode, *tnode2;
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if (huff->loc[ch] == NULL) { /* if this is the first transmission of this node */
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tnode = &(huff->nodeList[huff->blocNode++]);
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tnode2 = &(huff->nodeList[huff->blocNode++]);
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tnode2->symbol = INTERNAL_NODE;
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tnode2->weight = 1;
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tnode2->next = huff->lhead->next;
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if (huff->lhead->next) {
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huff->lhead->next->prev = tnode2;
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if (huff->lhead->next->weight == 1) {
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tnode2->head = huff->lhead->next->head;
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} else {
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tnode2->head = get_ppnode(huff);
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*tnode2->head = tnode2;
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}
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} else {
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tnode2->head = get_ppnode(huff);
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*tnode2->head = tnode2;
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}
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huff->lhead->next = tnode2;
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tnode2->prev = huff->lhead;
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tnode->symbol = ch;
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tnode->weight = 1;
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tnode->next = huff->lhead->next;
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if (huff->lhead->next) {
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huff->lhead->next->prev = tnode;
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if (huff->lhead->next->weight == 1) {
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tnode->head = huff->lhead->next->head;
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} else {
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/* this should never happen */
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tnode->head = get_ppnode(huff);
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*tnode->head = tnode2;
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}
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} else {
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/* this should never happen */
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tnode->head = get_ppnode(huff);
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*tnode->head = tnode;
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}
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huff->lhead->next = tnode;
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tnode->prev = huff->lhead;
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tnode->left = tnode->right = NULL;
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if (huff->lhead->parent) {
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if (huff->lhead->parent->left == huff->lhead) { /* lhead is guaranteed to by the NYT */
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huff->lhead->parent->left = tnode2;
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} else {
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huff->lhead->parent->right = tnode2;
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}
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} else {
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huff->tree = tnode2;
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}
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tnode2->right = tnode;
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tnode2->left = huff->lhead;
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tnode2->parent = huff->lhead->parent;
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huff->lhead->parent = tnode->parent = tnode2;
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huff->loc[ch] = tnode;
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increment(huff, tnode2->parent);
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} else {
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increment(huff, huff->loc[ch]);
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}
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}
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/* Get a symbol */
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int Huff_Receive (node_t *node, int *ch, byte *fin) {
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while (node && node->symbol == INTERNAL_NODE) {
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if (get_bit(fin)) {
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node = node->right;
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} else {
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node = node->left;
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}
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}
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if (!node) {
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return 0;
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// Com_Error(ERR_DROP, "Illegal tree!\n");
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}
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return (*ch = node->symbol);
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}
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/* Get a symbol */
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void Huff_offsetReceive (node_t *node, int *ch, byte *fin, int *offset) {
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bloc = *offset;
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while (node && node->symbol == INTERNAL_NODE) {
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if (get_bit(fin)) {
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node = node->right;
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} else {
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node = node->left;
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}
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}
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if (!node) {
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*ch = 0;
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return;
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// Com_Error(ERR_DROP, "Illegal tree!\n");
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}
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*ch = node->symbol;
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*offset = bloc;
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}
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/* Send the prefix code for this node */
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static void send(node_t *node, node_t *child, byte *fout) {
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if (node->parent) {
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send(node->parent, node, fout);
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}
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if (child) {
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if (node->right == child) {
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add_bit(1, fout);
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} else {
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add_bit(0, fout);
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}
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}
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}
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/* Send a symbol */
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void Huff_transmit (huff_t *huff, int ch, byte *fout) {
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int i;
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if (huff->loc[ch] == NULL) {
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/* node_t hasn't been transmitted, send a NYT, then the symbol */
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Huff_transmit(huff, NYT, fout);
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for (i = 7; i >= 0; i--) {
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add_bit((char)((ch >> i) & 0x1), fout);
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}
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} else {
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send(huff->loc[ch], NULL, fout);
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}
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}
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void Huff_offsetTransmit (huff_t *huff, int ch, byte *fout, int *offset) {
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bloc = *offset;
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send(huff->loc[ch], NULL, fout);
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*offset = bloc;
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}
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void Huff_Decompress(msg_t *mbuf, int offset) {
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int ch, cch, i, j, size;
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byte seq[65536];
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byte* buffer;
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huff_t huff;
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size = mbuf->cursize - offset;
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buffer = mbuf->data + offset;
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if ( size <= 0 ) {
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return;
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}
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Com_Memset(&huff, 0, sizeof(huff_t));
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// Initialize the tree & list with the NYT node
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huff.tree = huff.lhead = huff.ltail = huff.loc[NYT] = &(huff.nodeList[huff.blocNode++]);
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huff.tree->symbol = NYT;
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huff.tree->weight = 0;
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huff.lhead->next = huff.lhead->prev = NULL;
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huff.tree->parent = huff.tree->left = huff.tree->right = NULL;
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cch = buffer[0]*256 + buffer[1];
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// don't overflow with bad messages
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if ( cch > mbuf->maxsize - offset ) {
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cch = mbuf->maxsize - offset;
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}
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bloc = 16;
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for ( j = 0; j < cch; j++ ) {
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ch = 0;
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// don't overflow reading from the messages
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// FIXME: would it be better to have a overflow check in get_bit ?
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if ( (bloc >> 3) > size ) {
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seq[j] = 0;
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break;
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}
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Huff_Receive(huff.tree, &ch, buffer); /* Get a character */
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if ( ch == NYT ) { /* We got a NYT, get the symbol associated with it */
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ch = 0;
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for ( i = 0; i < 8; i++ ) {
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ch = (ch<<1) + get_bit(buffer);
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}
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}
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seq[j] = ch; /* Write symbol */
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Huff_addRef(&huff, (byte)ch); /* Increment node */
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}
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mbuf->cursize = cch + offset;
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Com_Memcpy(mbuf->data + offset, seq, cch);
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}
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extern int oldsize;
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void Huff_Compress(msg_t *mbuf, int offset) {
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int i, ch, size;
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byte seq[65536];
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byte* buffer;
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huff_t huff;
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size = mbuf->cursize - offset;
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buffer = mbuf->data+ + offset;
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if (size<=0) {
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return;
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}
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Com_Memset(&huff, 0, sizeof(huff_t));
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// Add the NYT (not yet transmitted) node into the tree/list */
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huff.tree = huff.lhead = huff.loc[NYT] = &(huff.nodeList[huff.blocNode++]);
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huff.tree->symbol = NYT;
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huff.tree->weight = 0;
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huff.lhead->next = huff.lhead->prev = NULL;
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huff.tree->parent = huff.tree->left = huff.tree->right = NULL;
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huff.loc[NYT] = huff.tree;
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seq[0] = (size>>8);
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seq[1] = size&0xff;
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bloc = 16;
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for (i=0; i<size; i++ ) {
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ch = buffer[i];
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Huff_transmit(&huff, ch, seq); /* Transmit symbol */
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Huff_addRef(&huff, (byte)ch); /* Do update */
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}
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bloc += 8; // next byte
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mbuf->cursize = (bloc>>3) + offset;
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Com_Memcpy(mbuf->data+offset, seq, (bloc>>3));
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}
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void Huff_Init(huffman_t *huff) {
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Com_Memset(&huff->compressor, 0, sizeof(huff_t));
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Com_Memset(&huff->decompressor, 0, sizeof(huff_t));
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// Initialize the tree & list with the NYT node
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huff->decompressor.tree = huff->decompressor.lhead = huff->decompressor.ltail = huff->decompressor.loc[NYT] = &(huff->decompressor.nodeList[huff->decompressor.blocNode++]);
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huff->decompressor.tree->symbol = NYT;
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huff->decompressor.tree->weight = 0;
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huff->decompressor.lhead->next = huff->decompressor.lhead->prev = NULL;
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huff->decompressor.tree->parent = huff->decompressor.tree->left = huff->decompressor.tree->right = NULL;
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// Add the NYT (not yet transmitted) node into the tree/list */
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huff->compressor.tree = huff->compressor.lhead = huff->compressor.loc[NYT] = &(huff->compressor.nodeList[huff->compressor.blocNode++]);
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huff->compressor.tree->symbol = NYT;
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huff->compressor.tree->weight = 0;
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huff->compressor.lhead->next = huff->compressor.lhead->prev = NULL;
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huff->compressor.tree->parent = huff->compressor.tree->left = huff->compressor.tree->right = NULL;
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huff->compressor.loc[NYT] = huff->compressor.tree;
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}
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