X-Git-Url: https://wimlib.net/git/?p=wimlib;a=blobdiff_plain;f=include%2Fwimlib%2Flzx_constants.h;h=beeff4362a456fb2a52042569bf679d5cd46ed96;hp=49cf8fafe4b59e471e31af0ac32e2a0a75c91a9e;hb=3e8aa757aaa63297f0d54007adf46411778fb6a8;hpb=94f8de6d411d58a0eb2e472cc1b984f195eb2447

diff --git a/include/wimlib/lzx_constants.h b/include/wimlib/lzx_constants.h
index 49cf8faf..beeff436 100644
--- 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 */