X-Git-Url: https://wimlib.net/git/?a=blobdiff_plain;f=include%2Fwimlib%2Flzms_constants.h;h=500be2427b573b9c562564b41f18b396f1d811a4;hb=6a84b7d59aa7cc0509ac870e5cbf122c5d755781;hp=aa22aaf297b946c41dcae148c9f76be042d1dbd8;hpb=855b49ef85d274588a2848d9c69974f9b88d343a;p=wimlib

diff --git a/include/wimlib/lzms_constants.h b/include/wimlib/lzms_constants.h
index aa22aaf2..500be242 100644
--- a/include/wimlib/lzms_constants.h
+++ b/include/wimlib/lzms_constants.h
@@ -7,42 +7,76 @@
 #ifndef _LZMS_CONSTANTS_H
 #define _LZMS_CONSTANTS_H
 
-#define LZMS_MIN_MATCH_LEN			1
-#define LZMS_MAX_MATCH_LEN			1073809578
+/* Limits on match lengths and offsets (in bytes)  */
+#define LZMS_MIN_MATCH_LENGTH			1
+#define LZMS_MAX_MATCH_LENGTH			1073809578
+#define LZMS_MIN_MATCH_OFFSET			1
 #define LZMS_MAX_MATCH_OFFSET			1180427428
-#define LZMS_MAX_BUFFER_SIZE			(LZMS_MAX_MATCH_OFFSET + 1)
 
-#define LZMS_NUM_RECENT_OFFSETS			3
-#define LZMS_MAX_INIT_RECENT_OFFSET		(LZMS_NUM_RECENT_OFFSETS + 1)
-#define LZMS_OFFSET_OFFSET			(LZMS_NUM_RECENT_OFFSETS - 1)
+/* The value to which buffer sizes should be limited.  Microsoft's
+ * implementation seems to use 67108864 (2^26) bytes.  However, since the format
+ * itself supports higher match lengths and offsets, we'll use 2^30 bytes.  */
+#define LZMS_MAX_BUFFER_SIZE			1073741824
 
+/* The length of each LRU queue for match sources:
+ *
+ *    1. offsets of LZ matches
+ *    2. (power, raw offset) pairs of delta matches */
+#define LZMS_NUM_LZ_REPS			3
+#define LZMS_NUM_DELTA_REPS			3
+
+/* The numbers of binary decision classes needed for encoding queue indices  */
+#define LZMS_NUM_LZ_REP_DECISIONS		(LZMS_NUM_LZ_REPS - 1)
+#define LZMS_NUM_DELTA_REP_DECISIONS		(LZMS_NUM_DELTA_REPS - 1)
+
+/* These are the numbers of probability entries for each binary decision class.
+ * The logarithm base 2 of each of these values is the number of recently
+ * encoded bits that are remembered for each decision class and are used to
+ * select the appropriate probability entry when decoding/encoding the next
+ * binary decision (bit).  */
+#define LZMS_NUM_MAIN_PROBS			16
+#define LZMS_NUM_MATCH_PROBS			32
+#define LZMS_NUM_LZ_PROBS			64
+#define LZMS_NUM_LZ_REP_PROBS			64
+#define LZMS_NUM_DELTA_PROBS			64
+#define LZMS_NUM_DELTA_REP_PROBS		64
+
+/* These values define the precision for probabilities in LZMS, which are always
+ * given as a numerator; the denominator is implied.  */
 #define LZMS_PROBABILITY_BITS			6
-#define LZMS_PROBABILITY_MAX			(1U << LZMS_PROBABILITY_BITS)
-#define LZMS_INITIAL_PROBABILITY		48
-#define LZMS_INITIAL_RECENT_BITS		0x0000000055555555ULL
+#define LZMS_PROBABILITY_DENOMINATOR		(1 << LZMS_PROBABILITY_BITS)
 
-#define LZMS_NUM_MAIN_STATES			16
-#define LZMS_NUM_MATCH_STATES			32
-#define LZMS_NUM_LZ_MATCH_STATES		64
-#define LZMS_NUM_LZ_REPEAT_MATCH_STATES		64
-#define LZMS_NUM_DELTA_MATCH_STATES		64
-#define LZMS_NUM_DELTA_REPEAT_MATCH_STATES	64
-#define LZMS_MAX_NUM_STATES			64
+/* These values define the initial state of each probability entry.  */
+#define LZMS_INITIAL_PROBABILITY		48
+#define LZMS_INITIAL_RECENT_BITS		0x0000000055555555
 
+/* The number of symbols in each Huffman-coded alphabet  */
 #define LZMS_NUM_LITERAL_SYMS			256
 #define LZMS_NUM_LENGTH_SYMS			54
 #define LZMS_NUM_DELTA_POWER_SYMS		8
 #define LZMS_MAX_NUM_OFFSET_SYMS		799
 #define LZMS_MAX_NUM_SYMS			799
 
-#define LZMS_MAX_CODEWORD_LEN			15
-
+/* The rebuild frequencies, in symbols, for each Huffman code  */
 #define LZMS_LITERAL_CODE_REBUILD_FREQ		1024
 #define LZMS_LZ_OFFSET_CODE_REBUILD_FREQ	1024
 #define LZMS_LENGTH_CODE_REBUILD_FREQ		512
 #define LZMS_DELTA_OFFSET_CODE_REBUILD_FREQ	1024
 #define LZMS_DELTA_POWER_CODE_REBUILD_FREQ	512
 
+/* The maximum length, in bits, of any Huffman codeword.  This is guaranteed by
+ * the way frequencies are updated.  */
+#define LZMS_MAX_CODEWORD_LENGTH		15
+
+/* The maximum number of verbatim bits, in addition to the Huffman-encoded
+ * length slot symbol, that may be required to encode a match length  */
+#define LZMS_MAX_EXTRA_LENGTH_BITS		30
+
+/* The maximum number of verbatim bits, in addition to the Huffman-encoded
+ * offset slot symbol, that may be required to encode a match offset  */
+#define LZMS_MAX_EXTRA_OFFSET_BITS		30
+
+/* Parameters for x86 machine code pre/post-processing  */
 #define LZMS_X86_ID_WINDOW_SIZE			65535
 #define LZMS_X86_MAX_TRANSLATION_OFFSET		1023