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-rw-r--r--src/liblzma/lzma/fastpos.h55
1 files changed, 28 insertions, 27 deletions
diff --git a/src/liblzma/lzma/fastpos.h b/src/liblzma/lzma/fastpos.h
index 4aea2318..a3feea58 100644
--- a/src/liblzma/lzma/fastpos.h
+++ b/src/liblzma/lzma/fastpos.h
@@ -14,15 +14,15 @@
#ifndef LZMA_FASTPOS_H
#define LZMA_FASTPOS_H
-// LZMA encodes match distances (positions) by storing the highest two
-// bits using a six-bit value [0, 63], and then the missing lower bits.
-// Dictionary size is also stored using this encoding in the new .lzma
+// LZMA encodes match distances by storing the highest two bits using
+// a six-bit value [0, 63], and then the missing lower bits.
+// Dictionary size is also stored using this encoding in the .xz
// file format header.
//
// fastpos.h provides a way to quickly find out the correct six-bit
// values. The following table gives some examples of this encoding:
//
-// pos return
+// dist return
// 0 0
// 1 1
// 2 2
@@ -48,10 +48,10 @@
// Provided functions or macros
// ----------------------------
//
-// get_pos_slot(pos) is the basic version. get_pos_slot_2(pos)
-// assumes that pos >= FULL_DISTANCES, thus the result is at least
-// FULL_DISTANCES_BITS * 2. Using get_pos_slot(pos) instead of
-// get_pos_slot_2(pos) would give the same result, but get_pos_slot_2(pos)
+// get_dist_slot(dist) is the basic version. get_dist_slot_2(dist)
+// assumes that dist >= FULL_DISTANCES, thus the result is at least
+// FULL_DISTANCES_BITS * 2. Using get_dist_slot(dist) instead of
+// get_dist_slot_2(dist) would give the same result, but get_dist_slot_2(dist)
// should be tiny bit faster due to the assumption being made.
//
//
@@ -76,13 +76,14 @@
// slightly faster, but sometimes it is a lot slower.
#ifdef HAVE_SMALL
-# define get_pos_slot(pos) ((pos) <= 4 ? (pos) : get_pos_slot_2(pos))
+# define get_dist_slot(dist) \
+ ((dist) <= 4 ? (dist) : get_dist_slot_2(dist))
static inline uint32_t
-get_pos_slot_2(uint32_t pos)
+get_dist_slot_2(uint32_t dist)
{
- const uint32_t i = bsr32(pos);
- return (i + i) + ((pos >> (i - 1)) & 1);
+ const uint32_t i = bsr32(dist);
+ return (i + i) + ((dist >> (i - 1)) & 1);
}
@@ -99,39 +100,39 @@ extern const uint8_t lzma_fastpos[1 << FASTPOS_BITS];
#define fastpos_limit(extra, n) \
(UINT32_C(1) << (FASTPOS_BITS + fastpos_shift(extra, n)))
-#define fastpos_result(pos, extra, n) \
- lzma_fastpos[(pos) >> fastpos_shift(extra, n)] \
+#define fastpos_result(dist, extra, n) \
+ lzma_fastpos[(dist) >> fastpos_shift(extra, n)] \
+ 2 * fastpos_shift(extra, n)
static inline uint32_t
-get_pos_slot(uint32_t pos)
+get_dist_slot(uint32_t dist)
{
// If it is small enough, we can pick the result directly from
// the precalculated table.
- if (pos < fastpos_limit(0, 0))
- return lzma_fastpos[pos];
+ if (dist < fastpos_limit(0, 0))
+ return lzma_fastpos[dist];
- if (pos < fastpos_limit(0, 1))
- return fastpos_result(pos, 0, 1);
+ if (dist < fastpos_limit(0, 1))
+ return fastpos_result(dist, 0, 1);
- return fastpos_result(pos, 0, 2);
+ return fastpos_result(dist, 0, 2);
}
#ifdef FULL_DISTANCES_BITS
static inline uint32_t
-get_pos_slot_2(uint32_t pos)
+get_dist_slot_2(uint32_t dist)
{
- assert(pos >= FULL_DISTANCES);
+ assert(dist >= FULL_DISTANCES);
- if (pos < fastpos_limit(FULL_DISTANCES_BITS - 1, 0))
- return fastpos_result(pos, FULL_DISTANCES_BITS - 1, 0);
+ if (dist < fastpos_limit(FULL_DISTANCES_BITS - 1, 0))
+ return fastpos_result(dist, FULL_DISTANCES_BITS - 1, 0);
- if (pos < fastpos_limit(FULL_DISTANCES_BITS - 1, 1))
- return fastpos_result(pos, FULL_DISTANCES_BITS - 1, 1);
+ if (dist < fastpos_limit(FULL_DISTANCES_BITS - 1, 1))
+ return fastpos_result(dist, FULL_DISTANCES_BITS - 1, 1);
- return fastpos_result(pos, FULL_DISTANCES_BITS - 1, 2);
+ return fastpos_result(dist, FULL_DISTANCES_BITS - 1, 2);
}
#endif