-/*
- * lzx.h
- *
- * Copyright (C) 2012 Eric Biggers
- *
- * wimlib - Library for working with WIM files
- *
- * This library is free software; you can redistribute it and/or modify it under
- * the terms of the GNU Lesser General Public License as published by the Free
- * Software Foundation; either version 2.1 of the License, or (at your option) any
- * later version.
- *
- * This library 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 Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License along
- * with this library; if not, write to the Free Software Foundation, Inc., 59
- * Temple Place, Suite 330, Boston, MA 02111-1307 USA
- */
-
#ifndef _WIMLIB_LZX_H
#define _WIMLIB_LZX_H
# define LZX_DEBUG(format, ...)
#endif
-
-/* Constants, some defined by the LZX specification: */
+/* Constants, most of which are defined by the LZX specification: */
/* The smallest and largest allowed match lengths. */
#define LZX_MIN_MATCH 2
/* Number of values an uncompressed literal byte can represent. */
#define LZX_NUM_CHARS 256
-/* Each LZX block begins with 3 bits that determines the block type: */
+/* Each LZX block begins with 3 bits that determines the block type. Below are
+ * the valid block types. Values 0, and 4 through 7, are invalid. */
#define LZX_BLOCKTYPE_VERBATIM 1
#define LZX_BLOCKTYPE_ALIGNED 2
#define LZX_BLOCKTYPE_UNCOMPRESSED 3
-/* values 0, and 4 through 7, are invalid. */
-
#define LZX_NUM_PRIMARY_LENS 7 /* this one missing from spec! */
-/* Only valid for 32768 block size! */
+/* NOTE: There are really 51 position slots in the LZX format as a whole, but
+ * only 30 are needed to allow for the window to be up to 32768 bytes long,
+ * which is the maximum in the WIM format. */
#define LZX_NUM_POSITION_SLOTS 30
/* Read the LZX specification for information about the Huffman trees used in
* read_code_lens() function and built using the make_decode_table() function.
* The decode table is not a real tree but rather a table that we can index by
* some number of bits (*_TABLEBITS) of the input to quickly look up the symbol
- * corresponding to a Huffman code.
+ * corresponding to a Huffman code.
*
* The ALIGNED tree is only present on ALIGNED blocks.
*
#define LZX_MAINTREE_NUM_SYMBOLS (LZX_NUM_CHARS + \
(LZX_NUM_POSITION_SLOTS << 3))
-#define LZX_MAINTREE_TABLEBITS 12
+#define LZX_MAINTREE_TABLEBITS 11
#define LZX_LENTREE_NUM_SYMBOLS 249
-#define LZX_LENTREE_TABLEBITS 12
+#define LZX_LENTREE_TABLEBITS 10
#define LZX_PRETREE_NUM_SYMBOLS 20
#define LZX_PRETREE_TABLEBITS 6
#define LZX_PRETREE_ELEMENT_SIZE 4
-
#define LZX_ALIGNEDTREE_NUM_SYMBOLS 8
#define LZX_ALIGNEDTREE_TABLEBITS 7
#define LZX_ALIGNEDTREE_ELEMENT_SIZE 3
* though the blocks themselves are not this size, and the size of the actual
* file resource in the WIM file is very likely to be something entirely
* different as well. */
-#define LZX_MAGIC_FILESIZE 12000000
+#define LZX_WIM_MAGIC_FILESIZE 12000000
+
+#define USE_LZX_EXTRA_BITS_ARRAY
+
+#ifdef USE_LZX_EXTRA_BITS_ARRAY
+extern const u8 lzx_extra_bits[LZX_NUM_POSITION_SLOTS];
+#endif
+
+/* Given the number of a LZX position slot, return the number of extra bits that
+ * are needed to encode the match offset. */
+static inline unsigned lzx_get_num_extra_bits(unsigned position_slot)
+{
+#ifdef USE_LZX_EXTRA_BITS_ARRAY
+ /* Use a table */
+ return lzx_extra_bits[position_slot];
+#else
+ /* Calculate directly using a shift and subtraction. */
+ wimlib_assert(position_slot >= 2 && position_slot <= 37);
+ return (position_slot >> 1) - 1;
+#endif
+}
-extern const u8 lzx_extra_bits[51];
-extern const u32 lzx_position_base[51];
+extern const u32 lzx_position_base[LZX_NUM_POSITION_SLOTS];
/* Least-recently used queue for match offsets. */
struct lru_queue {
- int R0;
- int R1;
- int R2;
+ u32 R0;
+ u32 R1;
+ u32 R2;
};
-extern int lzx_decompress(const void *compressed_data, uint compressed_len,
- void *uncompressed_data, uint uncompressed_len);
+extern int lzx_decompress(const void *compressed_data, unsigned compressed_len,
+ void *uncompressed_data, unsigned uncompressed_len);
-extern int lzx_compress(const void *uncompressed_data, uint uncompressed_len,
- void *compressed_data, uint *compressed_len_ret);
+extern int lzx_compress(const void *uncompressed_data, unsigned uncompressed_len,
+ void *compressed_data, unsigned *compressed_len_ret);
#endif /* _WIMLIB_LZX_H */
git://wimlib.net / wimlib / blobdiff