/* 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;
}
}
}
}
/* 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);
}
}
}
/* 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;
}
/* 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;
}
/* 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;
}
}
