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-rw-r--r--src/qcommon/huffman.c438
1 files changed, 438 insertions, 0 deletions
diff --git a/src/qcommon/huffman.c b/src/qcommon/huffman.c
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+++ b/src/qcommon/huffman.c
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+/*
+===========================================================================
+Copyright (C) 1999-2005 Id Software, Inc.
+Copyright (C) 2000-2006 Tim Angus
+
+This file is part of Tremulous.
+
+Tremulous 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.
+
+Tremulous 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 Tremulous; 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 "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;
+}
+
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