+/*
+ * lzx.h
+ *
+ * Declarations shared between LZX compression and decompression.
+ */
+
#ifndef _WIMLIB_LZX_H
#define _WIMLIB_LZX_H
#include "wimlib/assert.h"
+#include "wimlib/compiler.h"
+#include "wimlib/lzx_constants.h"
+#include "wimlib/util.h"
#include "wimlib/types.h"
//#define ENABLE_LZX_DEBUG
#ifdef ENABLE_LZX_DEBUG
-# define LZX_DEBUG DEBUG
+# define LZX_ASSERT wimlib_assert
#else
-# define LZX_DEBUG(format, ...)
+# define LZX_ASSERT(...)
#endif
-/* Constants, most of which are defined by the LZX specification: */
-
-/* The smallest and largest allowed match lengths. */
-#define LZX_MIN_MATCH 2
-#define LZX_MAX_MATCH 257
-
-/* 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. 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
-
-#define LZX_NUM_PRIMARY_LENS 7 /* this one missing from spec! */
-
-/* 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
- * the LZX compression format. Basically there are 4 of them: The main tree,
- * the length tree, the pre tree, and the aligned tree. The main tree and
- * length tree are given at the beginning of VERBATIM and ALIGNED blocks as a
- * list of *_NUM_SYMBOLS code length values. They are read using the
- * 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.
- *
- * The ALIGNED tree is only present on ALIGNED blocks.
- *
- * A PRETREE is used to encode the code lengths for the main tree and the length
- * tree. There is a separate pretree for each half of the main tree. */
-
-#define LZX_MAINTREE_NUM_SYMBOLS (LZX_NUM_CHARS + \
- (LZX_NUM_POSITION_SLOTS << 3))
-#define LZX_MAINTREE_TABLEBITS 11
-
-#define LZX_LENTREE_NUM_SYMBOLS 249
-#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
-
-/* Maximum allowed length of a Huffman code. */
-#define LZX_MAX_CODEWORD_LEN 16
-
-/* For the LZX-compressed blocks in WIM files, this value is always used as the
- * filesize parameter for the call instruction (0xe8 byte) preprocessing, even
- * 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_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];
+extern const u8 lzx_extra_bits[LZX_MAX_POSITION_SLOTS];
#endif
-/* Given the number of a LZX position slot, return the number of extra bits that
+/* Given the number of an 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)
return lzx_extra_bits[position_slot];
#else
/* Calculate directly using a shift and subtraction. */
- wimlib_assert(position_slot >= 2 && position_slot <= 37);
+ LZX_ASSERT(position_slot >= 2 && position_slot <= 37);
return (position_slot >> 1) - 1;
#endif
}
-extern const u32 lzx_position_base[LZX_NUM_POSITION_SLOTS];
+extern const u32 lzx_position_base[LZX_MAX_POSITION_SLOTS];
+
+/* Returns the LZX position slot that corresponds to a given formatted offset.
+ *
+ * Logically, this returns the smallest i such that
+ * formatted_offset >= lzx_position_base[i].
+ *
+ * The actual implementation below takes advantage of the regularity of the
+ * numbers in the lzx_position_base array to calculate the slot directly from
+ * the formatted offset without actually looking at the array.
+ */
+static inline unsigned
+lzx_get_position_slot_raw(u32 formatted_offset)
+{
+ if (formatted_offset >= 196608) {
+ return (formatted_offset >> 17) + 34;
+ } else {
+ LZX_ASSERT(2 <= formatted_offset && formatted_offset < 655360);
+ unsigned mssb_idx = bsr32(formatted_offset);
+ return (mssb_idx << 1) |
+ ((formatted_offset >> (mssb_idx - 1)) & 1);
+ }
+}
+
+extern unsigned lzx_get_window_order(size_t max_block_size);
+
+extern unsigned lzx_get_num_main_syms(unsigned window_order);
+
+/* Least-recently used queue for match offsets. */
+struct lzx_lru_queue {
+ u32 R[LZX_NUM_RECENT_OFFSETS];
+}
+#ifdef __x86_64__
+_aligned_attribute(8) /* Improves performance of LZX compression by 1% - 2%;
+ specifically, this speeds up
+ lzx_choose_near_optimal_item(). */
+#endif
+;
+
+/* Initialize the LZX least-recently-used match offset queue at the beginning of
+ * a new window for either decompression or compression. */
+static inline void
+lzx_lru_queue_init(struct lzx_lru_queue *queue)
+{
+ for (unsigned i = 0; i < LZX_NUM_RECENT_OFFSETS; i++)
+ queue->R[i] = 1;
+}
+
+extern void
+lzx_do_e8_preprocessing(u8 *data, u32 size);
-/* Least-recently used queue for match offsets. */
-struct lru_queue {
- u32 R0;
- u32 R1;
- u32 R2;
-};
+extern void
+lzx_undo_e8_preprocessing(u8 *data, u32 size);
#endif /* _WIMLIB_LZX_H */
git://wimlib.net / wimlib / blobdiff