huffman.cpp

魔兽解压DBC的一些功能代码,专门用来分解魔兽客户端所使用的代码

			item->prev = item2->prev;	/* Set prev item (or last item in the tree) */
			next2 = PTR_INT(p_item[0]);	/* Usually NULL */
			prev2 = item2->prev;		/* Prev item to the second (or last tree item) */
			if (PTR_INT(prev2) < 0) {
				prev2 = PTR_NOT(prev);
				prev2->next = item;
				item2->prev = item;	/* Next after last item */
				return;
			}
			if (next2 < 0) {
				next2 = item2 - item2->next->prev;
			}
			prev2 += next2;
			prev2->next = item;
			item2->prev = item;		/* Set the next/last item */
			return;
		default:
			return;
	}
}

/* Builds Huffman tree. Called with the first 8 bits loaded from input stream. */
static void libmpq_huff_build_tree(struct huffman_tree *ht, unsigned int cmp_type) {
	unsigned long max_byte;				/* [ESP+10] - The greatest character found in table */
	unsigned char *byte_array;			/* [ESP+1C] - Pointer to unsigned char in table1502A630 */
	unsigned long i;				/* egcs in linux doesn't like multiple for loops without an explicit i */
	unsigned int found;				/* Thats needed to replace the goto stuff from original source :) */
	struct huffman_tree_item **p_item;		/* [ESP+14] - Pointer to Huffman tree item pointer array */
	struct huffman_tree_item *child1;

	/* Loop while pointer has a negative value. */
	while (PTR_INT(ht->last) > 0) {			/* ESI - Last entry */
		struct huffman_tree_item *temp;		/* EAX */
        
		if (ht->last->next != NULL) {		/* ESI->next */
			libmpq_huff_remove_item(ht->last);
		}
		ht->item3058   = PTR_PTR(&ht->item3054);/* [EDI+4] */
		ht->last->prev = ht->item3058;		/* EAX */
		temp           = libmpq_huff_get_prev_item(PTR_PTR(&ht->item3054), PTR_INT(&ht->item3050));
		temp->next     = ht->last;
		ht->item3054   = ht->last;
	}

	/* Clear all pointers in huffman tree item array. */
	memset(ht->items306C, 0, sizeof(ht->items306C));

	max_byte = 0;					/* Greatest character found init to zero. */
	p_item = (struct huffman_tree_item **)&ht->items306C;	/* Pointer to current entry in huffman tree item pointer array */

	/* Ensure we have low 8 bits only */
	cmp_type   &= 0xFF;
	byte_array  = table1502A630 + cmp_type * 258;	/* EDI also */

	for (i = 0; i < 0x100; i++, p_item++) {
		struct huffman_tree_item *item = ht->item3058;	/* Item to be created */
		struct huffman_tree_item *p_item3 = ht->item3058;
		unsigned char one_byte = byte_array[i];

		/* Skip all the bytes which are zero. */
		if (byte_array[i] == 0) {
			continue;
		}

		/* If not valid pointer, take the first available item in the array. */
		if (PTR_INT(item) <= 0) {
			item = &ht->items0008[ht->items++];
		}

		/* Insert this item as the top of the tree. */
		libmpq_huff_insert_item(&ht->item305C, item, SWITCH_ITEMS, NULL);

		item->parent    = NULL;			/* Invalidate child and parent */
		item->child     = NULL;
		*p_item         = item;			/* Store pointer into pointer array */

		item->dcmp_byte  = i;			/* Store counter */
		item->byte_value = one_byte;		/* Store byte value */
		if (one_byte >= max_byte) {
			max_byte = one_byte;
			continue;
		}

		/* Find the first item which has byte value greater than current one byte */
		found = 0;
		if (PTR_INT((p_item3 = ht->last)) > 0) {/* EDI - Pointer to the last item */

			/* 15006AF7 */
			if (p_item3 != NULL) {
				do {			/* 15006AFB */
					if (p_item3->byte_value >= one_byte) {
						found = 1;
						break;
					}
					p_item3 = p_item3->prev;
				} while (PTR_INT(p_item3) > 0);
			}
		}

		if (found == 0) {
			p_item3 = NULL;
		}

		/* 15006B09 */
		if (item->next != NULL) {
			libmpq_huff_remove_item(item);
		}

		/* 15006B15 */
		if (p_item3 == NULL) {
			p_item3 = PTR_PTR(&ht->first);
		}

		/* 15006B1F */
		item->next = p_item3->next;
		item->prev = p_item3->next->prev;
		p_item3->next->prev = item;
		p_item3->next = item;
	}

	/* 15006B4A */
	for (; i < 0x102; i++) {
		struct huffman_tree_item **p_item2 = &ht->items306C[i];	/* EDI */

		/* 15006B59  */
		struct huffman_tree_item *item2 = ht->item3058;	/* ESI */
		if (PTR_INT(item2) <= 0) {
			item2 = &ht->items0008[ht->items++];
		}
		libmpq_huff_insert_item(&ht->item305C, item2, INSERT_ITEM, NULL);

		/* 15006B89 */
		item2->dcmp_byte  = i;
		item2->byte_value = 1;
		item2->parent     = NULL;
		item2->child      = NULL;
		*p_item2++        = item2;
	}

	/* 15006BAA */
	if (PTR_INT((child1 = ht->last)) > 0) {		/* EDI - last item (first child to item */
		struct huffman_tree_item *child2;	/* EBP */
		struct huffman_tree_item *item;		/* ESI */

		/* 15006BB8 */
		while (PTR_INT((child2 = child1->prev)) > 0) {
			if (PTR_INT((item = ht->item3058)) <= 0) {
				item = &ht->items0008[ht->items++];
			}
			/* 15006BE3 */
			libmpq_huff_insert_item(&ht->item305C, item, SWITCH_ITEMS, NULL);

			/* 15006BF3 */
			item->parent = NULL;
			item->child  = NULL;

			/*
			 * EDX = child2->byte_value + child1->byte_value;
			 * EAX = child1->byte_value;
			 * ECX = max_byte;		The greatest character (0xFF usually)
			 */
			item->byte_value = child1->byte_value + child2->byte_value;	/* 0x02 */
			item->child      = child1;	/* Prev item in the */
			child1->parent   = item;
			child2->parent   = item;

			/* EAX = item->byte_value; */
			if (item->byte_value >= max_byte) {
				max_byte = item->byte_value;
			} else {
				struct huffman_tree_item *p_item2 = child2->prev;	/* EDI */
				found = 0;
				if (PTR_INT(p_item2) > 0) {

					/* 15006C2D */
					do {
						if (p_item2->byte_value >= item->byte_value) {
							found = 1;
							break;
						}
						p_item2 = p_item2->prev;
					} while (PTR_INT(p_item2) > 0);
				}
				if (found == 0) {
					p_item2 = NULL;
				}
				if (item->next != 0) {
					struct huffman_tree_item *temp4 = libmpq_huff_get_prev_item(item, -1);
					temp4->next      = item->next;	/* The first item changed */
					item->next->prev = item->prev;	/* First->prev changed to negative value */
					item->next = NULL;
					item->prev = NULL;
				}

				/* 15006C62 */
				if (p_item2 == NULL) {
					p_item2 = PTR_PTR(&ht->first);
				}
				item->next = p_item2->next;		/* Set item with 0x100 byte value */
				item->prev = p_item2->next->prev;	/* Set item with 0x17 byte value */
				p_item2->next->prev = item;		/* Changed prev of item with */
				p_item2->next = item;
			}

			/* 15006C7B */
			if (PTR_INT((child1 = child2->prev)) <= 0) {
				break;
			}
		}
	}

	/* 15006C88 */
	ht->offs0004 = 1;
}

/* Gets the whole byte from the input stream. */
static unsigned long libmpq_huff_get_8bits(struct huffman_input_stream *is) {
	unsigned long one_byte;

	if (is->bits <= 8) {
		is->bit_buf |= *(unsigned short *)is->in_buf << is->bits;
		is->in_buf  += sizeof(unsigned short);
		is->bits    += 16;
	}

	one_byte      = (is->bit_buf & 0xFF);
	is->bit_buf >>= 8;
	is->bits     -= 8;

	return one_byte;
}

/* Gets 7 bits from the stream. */
static unsigned long libmpq_huff_get_7bits(struct huffman_input_stream *is) {
	if (is->bits <= 7) {
		is->bit_buf |= *(unsigned short *)is->in_buf << is->bits;
		is->in_buf  += sizeof(unsigned short);
		is->bits    += 16;
	}

	/* Get 7 bits from input stream. */
	return (is->bit_buf & 0x7F);
}

/* Gets one bit from input stream. */
unsigned long libmpq_huff_get_bit(struct huffman_input_stream *is) {
	unsigned long bit = (is->bit_buf & 1);

	is->bit_buf >>= 1;
	if (--is->bits == 0) {
		is->bit_buf  = *(unsigned long *)is->in_buf;
		is->in_buf  += sizeof(unsigned long);
		is->bits     = 32;
	}
	return bit;
}

static struct huffman_tree_item *libmpq_huff_call1500E740(struct huffman_tree *ht, unsigned int value) {
	struct huffman_tree_item *p_item1 = ht->item3058;	/* EDX */
	struct huffman_tree_item *p_item2;			/* EAX */
	struct huffman_tree_item *p_next;
	struct huffman_tree_item *p_prev;
	struct huffman_tree_item **pp_item;

	if (PTR_INT(p_item1) <= 0 || (p_item2 = p_item1) == NULL) {
		if((p_item2 = &ht->items0008[ht->items++]) != NULL) {
			p_item1 = p_item2;
		} else {
			p_item1 = ht->first;
		}
	} else {
		p_item1 = p_item2;
	}

	p_next = p_item1->next;
	if (p_next != NULL) {
		p_prev = p_item1->prev;
		if (PTR_INT(p_prev) <= 0) {