Compression updates

[wimlib] / include / wimlib / lzx.h

diff --git a/include/wimlib/lzx.h b/include/wimlib/lzx.h
index 97d4a691c62ab46f13de4a66840af687a8b99d58..da0c55143c4bc9a569bdc5550b51c0e16c16d80b 100644 (file)
--- a/include/wimlib/lzx.h
+++ b/include/wimlib/lzx.h
@@ -20,48 +20,29 @@
 #      define LZX_ASSERT(...)
 #endif
 
-#define USE_LZX_EXTRA_BITS_ARRAY
+extern const u32 lzx_offset_slot_base[LZX_MAX_OFFSET_SLOTS];
 
-#ifdef USE_LZX_EXTRA_BITS_ARRAY
-extern const u8 lzx_extra_bits[LZX_MAX_POSITION_SLOTS];
-#endif
-
-/* 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)
-{
-#ifdef USE_LZX_EXTRA_BITS_ARRAY
-       /* Use a table */
-       return lzx_extra_bits[position_slot];
-#else
-       /* Calculate directly using a shift and subtraction. */
-       LZX_ASSERT(position_slot >= 2 && position_slot <= 37);
-       return (position_slot >> 1) - 1;
-#endif
-}
-
-extern const u32 lzx_position_base[LZX_MAX_POSITION_SLOTS];
+extern const u8 lzx_extra_offset_bits[LZX_MAX_OFFSET_SLOTS];
 
-/* Returns the LZX position slot that corresponds to a given formatted offset.
+/* Returns the LZX offset slot that corresponds to a given adjusted offset.
  *
  * Logically, this returns the smallest i such that
- * formatted_offset >= lzx_position_base[i].
+ * adjusted_offset >= lzx_offset_slot_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.
+ * numbers in the lzx_offset_slot_base array to calculate the slot directly from
+ * the adjusted offset without actually looking at the array.
  */
 static inline unsigned
-lzx_get_position_slot_raw(u32 formatted_offset)
+lzx_get_offset_slot_raw(u32 adjusted_offset)
 {
-       if (formatted_offset >= 196608) {
-               return (formatted_offset >> 17) + 34;
+       if (adjusted_offset >= 196608) {
+               return (adjusted_offset >> 17) + 34;
        } else {
-               LZX_ASSERT(2 <= formatted_offset && formatted_offset < 655360);
-               unsigned mssb_idx = bsr32(formatted_offset);
+               LZX_ASSERT(2 <= adjusted_offset && adjusted_offset < 655360);
+               unsigned mssb_idx = bsr32(adjusted_offset);
                return (mssb_idx << 1) |
-                       ((formatted_offset >> (mssb_idx - 1)) & 1);
+                       ((adjusted_offset >> (mssb_idx - 1)) & 1);
        }
 }
 
@@ -72,13 +53,7 @@ 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
-;
+} _aligned_attribute(sizeof(unsigned long));
 
 /* Initialize the LZX least-recently-used match offset queue at the beginning of
  * a new window for either decompression or compression.  */