Merge LZX compression updates

[wimlib] / include / wimlib / lzx_constants.h

diff --git a/include/wimlib/lzx_constants.h b/include/wimlib/lzx_constants.h
index 49cf8fafe4b59e471e31af0ac32e2a0a75c91a9e..beeff4362a456fb2a52042569bf679d5cd46ed96 100644 (file)
--- a/include/wimlib/lzx_constants.h
+++ b/include/wimlib/lzx_constants.h
@@ -7,38 +7,43 @@
 #ifndef _LZX_CONSTANTS_H
 #define _LZX_CONSTANTS_H
 
+/* Number of literal byte values.  */
+#define LZX_NUM_CHARS  256
+
 /* The smallest and largest allowed match lengths.  */
 #define LZX_MIN_MATCH_LEN      2
 #define LZX_MAX_MATCH_LEN      257
 
-/* Number of values an uncompressed literal byte can represent.  */
-#define LZX_NUM_CHARS  256
+/* Number of distinct match lengths that can be represented.  */
+#define LZX_NUM_LENS           (LZX_MAX_MATCH_LEN - LZX_MIN_MATCH_LEN + 1)
+
+/* Number of match lengths for which no length symbol is required.  */
+#define LZX_NUM_PRIMARY_LENS   7
+#define LZX_NUM_LEN_HEADERS    (LZX_NUM_PRIMARY_LENS + 1)
 
 /* Valid values of the 3-bit block type field.  */
 #define LZX_BLOCKTYPE_VERBATIM       1
 #define LZX_BLOCKTYPE_ALIGNED        2
 #define LZX_BLOCKTYPE_UNCOMPRESSED   3
 
-/* Maximum value of the "length header" portion of a main symbol.  If the length
- * header has this value, then the match length is at least LZX_NUM_PRIMARY_LENS
- * + LZX_MIN_MATCH_LEN, and a length symbol follows.  */
-#define LZX_NUM_PRIMARY_LENS         7
-
-/* Maximum number of offset slots.  The actual number of offset slots will
- * depend on the window size.  */
-#define LZX_MAX_OFFSET_SLOTS   51
-
+/* 'LZX_MIN_WINDOW_SIZE' and 'LZX_MAX_WINDOW_SIZE' are the minimum and maximum
+ * sizes of the sliding window.  */
 #define LZX_MIN_WINDOW_ORDER   15
 #define LZX_MAX_WINDOW_ORDER   21
-#define LZX_MIN_WINDOW_SIZE    (1U << LZX_MIN_WINDOW_ORDER)  /* 32768   */
-#define LZX_MAX_WINDOW_SIZE    (1U << LZX_MAX_WINDOW_ORDER)  /* 2097152 */
+#define LZX_MIN_WINDOW_SIZE    (1UL << LZX_MIN_WINDOW_ORDER)  /* 32768   */
+#define LZX_MAX_WINDOW_SIZE    (1UL << LZX_MAX_WINDOW_ORDER)  /* 2097152 */
+
+/* Maximum number of offset slots.  (The actual number of offset slots depends
+ * on the window size.)  */
+#define LZX_MAX_OFFSET_SLOTS   50
 
-/* Maximum number of symbols in the main code.  The actual number of symbols in
- * the main code will depend on the window size.  */
-#define LZX_MAINCODE_MAX_NUM_SYMBOLS   (LZX_NUM_CHARS + (LZX_MAX_OFFSET_SLOTS << 3))
+/* Maximum number of symbols in the main code.  (The actual number of symbols in
+ * the main code depends on the window size.)  */
+#define LZX_MAINCODE_MAX_NUM_SYMBOLS   \
+       (LZX_NUM_CHARS + (LZX_MAX_OFFSET_SLOTS * LZX_NUM_LEN_HEADERS))
 
 /* Number of symbols in the length code.  */
-#define LZX_LENCODE_NUM_SYMBOLS                249
+#define LZX_LENCODE_NUM_SYMBOLS                (LZX_NUM_LENS - LZX_NUM_PRIMARY_LENS)
 
 /* Number of symbols in the pre-code.  */
 #define LZX_PRECODE_NUM_SYMBOLS                20
@@ -46,8 +51,16 @@
 /* Number of bits in which each pre-code codeword length is represented.  */
 #define LZX_PRECODE_ELEMENT_SIZE       4
 
+/* Number of low-order bits of each match offset that are entropy-encoded in
+ * aligned offset blocks.  */
+#define LZX_NUM_ALIGNED_OFFSET_BITS    3
+
 /* Number of symbols in the aligned offset code.  */
-#define LZX_ALIGNEDCODE_NUM_SYMBOLS    8
+#define LZX_ALIGNEDCODE_NUM_SYMBOLS    (1 << LZX_NUM_ALIGNED_OFFSET_BITS)
+
+/* Mask for the match offset bits that are entropy-encoded in aligned offset
+ * blocks.  */
+#define LZX_ALIGNED_OFFSET_BITMASK     ((1 << LZX_NUM_ALIGNED_OFFSET_BITS) - 1)
 
 /* Number of bits in which each aligned offset codeword length is represented.  */
 #define LZX_ALIGNEDCODE_ELEMENT_SIZE   3
@@ -55,8 +68,8 @@
 /* Maximum lengths (in bits) for length-limited Huffman code construction.  */
 #define LZX_MAX_MAIN_CODEWORD_LEN      16
 #define LZX_MAX_LEN_CODEWORD_LEN       16
-#define LZX_MAX_PRE_CODEWORD_LEN       16
-#define LZX_MAX_ALIGNED_CODEWORD_LEN   8
+#define LZX_MAX_PRE_CODEWORD_LEN       ((1 << LZX_PRECODE_ELEMENT_SIZE) - 1)
+#define LZX_MAX_ALIGNED_CODEWORD_LEN   ((1 << LZX_ALIGNEDCODE_ELEMENT_SIZE) - 1)
 
 /* For LZX-compressed blocks in WIM resources, this value is always used as the
  * filesize parameter for the call instruction (0xe8 byte) preprocessing, even
@@ -72,7 +85,7 @@
 /* Number of offsets in the recent (or "repeat") offsets queue.  */
 #define LZX_NUM_RECENT_OFFSETS 3
 
-/* An offset of n bytes is actually encoded as (n + LZX_OFFSET_OFFSET).  */
-#define LZX_OFFSET_OFFSET      (LZX_NUM_RECENT_OFFSETS - 1)
+/* An offset of n bytes is actually encoded as (n + LZX_OFFSET_ADJUSTMENT).  */
+#define LZX_OFFSET_ADJUSTMENT  (LZX_NUM_RECENT_OFFSETS - 1)
 
 #endif /* _LZX_CONSTANTS_H */