X-Git-Url: https://wimlib.net/git/?p=wimlib;a=blobdiff_plain;f=src%2Flzx.h;h=5f87076e6a100363a3f98b4c149047ca40189f75;hp=b44fecffb74c0c1710923bb45b75e5699a257703;hb=9e2571b03cd9c71d11b3dad9ea5dcfa43f50deb4;hpb=6f77434ea6ff1407603410e28d1edb966c40e568

diff --git a/src/lzx.h b/src/lzx.h
index b44fecff..5f87076e 100644
--- a/src/lzx.h
+++ b/src/lzx.h
@@ -10,8 +10,7 @@
 #	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
@@ -20,16 +19,17 @@
 /* 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
@@ -40,7 +40,7 @@
  * 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.
  *
@@ -49,16 +49,15 @@
 
 #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
@@ -71,22 +70,36 @@
  * 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
 
-extern const u8 lzx_extra_bits[51];
-extern const u32 lzx_position_base[51];
+#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 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_compress(const void *uncompressed_data, uint uncompressed_len,
-			void *compressed_data, uint *compressed_len_ret);
-
 #endif /* _WIMLIB_LZX_H */