liblzma: Rename a few variables and constants.

This has no semantic changes. I find the new names slightly
more logical and they match the names that are already used
in XZ Embedded.

The name fastpos wasn't changed (not worth the hassle).

8 files changed, 183 insertions, 186 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
 
diff --git a/src/liblzma/lzma/lzma2_encoder.c b/src/liblzma/lzma/lzma2_encoder.c
index b48e0d68..e734bc53 100644
--- a/src/liblzma/lzma/lzma2_encoder.c
+++ b/src/liblzma/lzma/lzma2_encoder.c
@@ -387,7 +387,7 @@ lzma_lzma2_props_encode(const void *options, uint8_t *out)
 	if (d == UINT32_MAX)
 		out[0] = 40;
 	else
-		out[0] = get_pos_slot(d + 1) - 24;
+		out[0] = get_dist_slot(d + 1) - 24;
 
 	return LZMA_OK;
 }
diff --git a/src/liblzma/lzma/lzma_common.h b/src/liblzma/lzma/lzma_common.h
index e31e285f..09efd387 100644
--- a/src/liblzma/lzma/lzma_common.h
+++ b/src/liblzma/lzma/lzma_common.h
@@ -171,53 +171,54 @@ literal_init(probability (*probs)[LITERAL_CODER_SIZE],
 // Match distance //
 ////////////////////
 
-// Different set of probabilities is used for match distances that have very
+// Different sets of probabilities are used for match distances that have very
 // short match length: Lengths of 2, 3, and 4 bytes have a separate set of
 // probabilities for each length. The matches with longer length use a shared
 // set of probabilities.
-#define LEN_TO_POS_STATES 4
+#define DIST_STATES 4
 
 // Macro to get the index of the appropriate probability array.
-#define get_len_to_pos_state(len) \
-	((len) < LEN_TO_POS_STATES + MATCH_LEN_MIN \
+#define get_dist_state(len) \
+	((len) < DIST_STATES + MATCH_LEN_MIN \
 		? (len) - MATCH_LEN_MIN \
-		: LEN_TO_POS_STATES - 1)
+		: DIST_STATES - 1)
 
-// The highest two bits of a match distance (pos slot) are encoded using six
-// bits. See fastpos.h for more explanation.
-#define POS_SLOT_BITS 6
-#define POS_SLOTS (1 << POS_SLOT_BITS)
+// The highest two bits of a match distance (distance slot) are encoded
+// using six bits. See fastpos.h for more explanation.
+#define DIST_SLOT_BITS 6
+#define DIST_SLOTS (1 << DIST_SLOT_BITS)
 
 // Match distances up to 127 are fully encoded using probabilities. Since
-// the highest two bits (pos slot) are always encoded using six bits, the
-// distances 0-3 don't need any additional bits to encode, since the pos
-// slot itself is the same as the actual distance. START_POS_MODEL_INDEX
-// indicates the first pos slot where at least one additional bit is needed.
-#define START_POS_MODEL_INDEX 4
+// the highest two bits (distance slot) are always encoded using six bits,
+// the distances 0-3 don't need any additional bits to encode, since the
+// distance slot itself is the same as the actual distance. DIST_MODEL_START
+// indicates the first distance slot where at least one additional bit is
+// needed.
+#define DIST_MODEL_START 4
 
 // Match distances greater than 127 are encoded in three pieces:
-//   - pos slot: the highest two bits
+//   - distance slot: the highest two bits
 //   - direct bits: 2-26 bits below the highest two bits
 //   - alignment bits: four lowest bits
 //
 // Direct bits don't use any probabilities.
 //
-// The pos slot value of 14 is for distances 128-191 (see the table in
+// The distance slot value of 14 is for distances 128-191 (see the table in
 // fastpos.h to understand why).
-#define END_POS_MODEL_INDEX 14
+#define DIST_MODEL_END 14
 
-// Pos slots that indicate a distance <= 127.
-#define FULL_DISTANCES_BITS (END_POS_MODEL_INDEX / 2)
+// Distance slots that indicate a distance <= 127.
+#define FULL_DISTANCES_BITS (DIST_MODEL_END / 2)
 #define FULL_DISTANCES (1 << FULL_DISTANCES_BITS)
 
 // For match distances greater than 127, only the highest two bits and the
 // lowest four bits (alignment) is encoded using probabilities.
 #define ALIGN_BITS 4
-#define ALIGN_TABLE_SIZE (1 << ALIGN_BITS)
-#define ALIGN_MASK (ALIGN_TABLE_SIZE - 1)
+#define ALIGN_SIZE (1 << ALIGN_BITS)
+#define ALIGN_MASK (ALIGN_SIZE - 1)
 
 // LZMA remembers the four most recent match distances. Reusing these distances
 // tends to take less space than re-encoding the actual distance value.
-#define REP_DISTANCES 4
+#define REPS 4
 
 #endif
diff --git a/src/liblzma/lzma/lzma_decoder.c b/src/liblzma/lzma/lzma_decoder.c
index 9979bb42..d61b7dee 100644
--- a/src/liblzma/lzma/lzma_decoder.c
+++ b/src/liblzma/lzma/lzma_decoder.c
@@ -193,15 +193,15 @@ struct lzma_coder_s {
 	/// Probability tree for the highest two bits of the match distance.
 	/// There is a separate probability tree for match lengths of
 	/// 2 (i.e. MATCH_LEN_MIN), 3, 4, and [5, 273].
-	probability pos_slot[LEN_TO_POS_STATES][POS_SLOTS];
+	probability dist_slot[DIST_STATES][DIST_SLOTS];
 
 	/// Probability trees for additional bits for match distance when the
 	/// distance is in the range [4, 127].
-	probability pos_special[FULL_DISTANCES - END_POS_MODEL_INDEX];
+	probability pos_special[FULL_DISTANCES - DIST_MODEL_END];
 
 	/// Probability tree for the lowest four bits of a match distance
 	/// that is equal to or greater than 128.
-	probability pos_align[ALIGN_TABLE_SIZE];
+	probability pos_align[ALIGN_SIZE];
 
 	/// Length of a normal match
 	lzma_length_decoder match_len_decoder;
@@ -245,8 +245,8 @@ struct lzma_coder_s {
 		SEQ_LITERAL_WRITE,
 		SEQ_IS_REP,
 		seq_len(SEQ_MATCH_LEN),
-		seq_6(SEQ_POS_SLOT),
-		SEQ_POS_MODEL,
+		seq_6(SEQ_DIST_SLOT),
+		SEQ_DIST_MODEL,
 		SEQ_DIRECT,
 		seq_4(SEQ_ALIGN),
 		SEQ_EOPM,
@@ -502,28 +502,28 @@ lzma_decode(lzma_coder *restrict coder, lzma_dict *restrict dictptr,
 
 			// Prepare to decode the highest two bits of the
 			// match distance.
-			probs = coder->pos_slot[get_len_to_pos_state(len)];
+			probs = coder->dist_slot[get_dist_state(len)];
 			symbol = 1;
 
 #ifdef HAVE_SMALL
-	case SEQ_POS_SLOT:
+	case SEQ_DIST_SLOT:
 			do {
-				rc_bit(probs[symbol], , , SEQ_POS_SLOT);
-			} while (symbol < POS_SLOTS);
+				rc_bit(probs[symbol], , , SEQ_DIST_SLOT);
+			} while (symbol < DIST_SLOTS);
 #else
-			rc_bit_case(probs[symbol], , , SEQ_POS_SLOT0);
-			rc_bit_case(probs[symbol], , , SEQ_POS_SLOT1);
-			rc_bit_case(probs[symbol], , , SEQ_POS_SLOT2);
-			rc_bit_case(probs[symbol], , , SEQ_POS_SLOT3);
-			rc_bit_case(probs[symbol], , , SEQ_POS_SLOT4);
-			rc_bit_case(probs[symbol], , , SEQ_POS_SLOT5);
+			rc_bit_case(probs[symbol], , , SEQ_DIST_SLOT0);
+			rc_bit_case(probs[symbol], , , SEQ_DIST_SLOT1);
+			rc_bit_case(probs[symbol], , , SEQ_DIST_SLOT2);
+			rc_bit_case(probs[symbol], , , SEQ_DIST_SLOT3);
+			rc_bit_case(probs[symbol], , , SEQ_DIST_SLOT4);
+			rc_bit_case(probs[symbol], , , SEQ_DIST_SLOT5);
 #endif
 			// Get rid of the highest bit that was needed for
 			// indexing of the probability array.
-			symbol -= POS_SLOTS;
+			symbol -= DIST_SLOTS;
 			assert(symbol <= 63);
 
-			if (symbol < START_POS_MODEL_INDEX) {
+			if (symbol < DIST_MODEL_START) {
 				// Match distances [0, 3] have only two bits.
 				rep0 = symbol;
 			} else {
@@ -533,7 +533,7 @@ lzma_decode(lzma_coder *restrict coder, lzma_dict *restrict dictptr,
 				assert(limit >= 1 && limit <= 30);
 				rep0 = 2 + (symbol & 1);
 
-				if (symbol < END_POS_MODEL_INDEX) {
+				if (symbol < DIST_MODEL_END) {
 					// Prepare to decode the low bits for
 					// a distance of [4, 127].
 					assert(limit <= 5);
@@ -553,12 +553,12 @@ lzma_decode(lzma_coder *restrict coder, lzma_dict *restrict dictptr,
 							- symbol - 1;
 					symbol = 1;
 					offset = 0;
-	case SEQ_POS_MODEL:
+	case SEQ_DIST_MODEL:
 #ifdef HAVE_SMALL
 					do {
 						rc_bit(probs[symbol], ,
 							rep0 += 1 << offset,
-							SEQ_POS_MODEL);
+							SEQ_DIST_MODEL);
 					} while (++offset < limit);
 #else
 					switch (limit) {
@@ -566,25 +566,25 @@ lzma_decode(lzma_coder *restrict coder, lzma_dict *restrict dictptr,
 						assert(offset == 0);
 						rc_bit(probs[symbol], ,
 							rep0 += 1,
-							SEQ_POS_MODEL);
+							SEQ_DIST_MODEL);
 						++offset;
 						--limit;
 					case 4:
 						rc_bit(probs[symbol], ,
 							rep0 += 1 << offset,
-							SEQ_POS_MODEL);
+							SEQ_DIST_MODEL);
 						++offset;
 						--limit;
 					case 3:
 						rc_bit(probs[symbol], ,
 							rep0 += 1 << offset,
-							SEQ_POS_MODEL);
+							SEQ_DIST_MODEL);
 						++offset;
 						--limit;
 					case 2:
 						rc_bit(probs[symbol], ,
 							rep0 += 1 << offset,
-							SEQ_POS_MODEL);
+							SEQ_DIST_MODEL);
 						++offset;
 						--limit;
 					case 1:
@@ -596,7 +596,7 @@ lzma_decode(lzma_coder *restrict coder, lzma_dict *restrict dictptr,
 						// "symbol".
 						rc_bit_last(probs[symbol], ,
 							rep0 += 1 << offset,
-							SEQ_POS_MODEL);
+							SEQ_DIST_MODEL);
 					}
 #endif
 				} else {
@@ -637,7 +637,7 @@ lzma_decode(lzma_coder *restrict coder, lzma_dict *restrict dictptr,
 					rc_bit(coder->pos_align[symbol], ,
 							rep0 += 4, SEQ_ALIGN2);
 	case SEQ_ALIGN3:
-					// Like in SEQ_POS_MODEL, we don't
+					// Like in SEQ_DIST_MODEL, we don't
 					// need "symbol" for anything else
 					// than indexing the probability array.
 					rc_bit_last(coder->pos_align[symbol], ,
@@ -891,10 +891,10 @@ lzma_decoder_reset(lzma_coder *coder, const void *opt)
 		bit_reset(coder->is_rep2[i]);
 	}
 
-	for (uint32_t i = 0; i < LEN_TO_POS_STATES; ++i)
-		bittree_reset(coder->pos_slot[i], POS_SLOT_BITS);
+	for (uint32_t i = 0; i < DIST_STATES; ++i)
+		bittree_reset(coder->dist_slot[i], DIST_SLOT_BITS);
 
-	for (uint32_t i = 0; i < FULL_DISTANCES - END_POS_MODEL_INDEX; ++i)
+	for (uint32_t i = 0; i < FULL_DISTANCES - DIST_MODEL_END; ++i)
 		bit_reset(coder->pos_special[i]);
 
 	bittree_reset(coder->pos_align, ALIGN_BITS);
diff --git a/src/liblzma/lzma/lzma_encoder.c b/src/liblzma/lzma/lzma_encoder.c
index 0b9ee9e1..0f91653c 100644
--- a/src/liblzma/lzma/lzma_encoder.c
+++ b/src/liblzma/lzma/lzma_encoder.c
@@ -148,28 +148,28 @@ match(lzma_coder *coder, const uint32_t pos_state,
 	length(&coder->rc, &coder->match_len_encoder, pos_state, len,
 			coder->fast_mode);
 
-	const uint32_t pos_slot = get_pos_slot(distance);
-	const uint32_t len_to_pos_state = get_len_to_pos_state(len);
-	rc_bittree(&coder->rc, coder->pos_slot[len_to_pos_state],
-			POS_SLOT_BITS, pos_slot);
-
-	if (pos_slot >= START_POS_MODEL_INDEX) {
-		const uint32_t footer_bits = (pos_slot >> 1) - 1;
-		const uint32_t base = (2 | (pos_slot & 1)) << footer_bits;
-		const uint32_t pos_reduced = distance - base;
-
-		if (pos_slot < END_POS_MODEL_INDEX) {
-			// Careful here: base - pos_slot - 1 can be -1, but
+	const uint32_t dist_slot = get_dist_slot(distance);
+	const uint32_t dist_state = get_dist_state(len);
+	rc_bittree(&coder->rc, coder->dist_slot[dist_state],
+			DIST_SLOT_BITS, dist_slot);
+
+	if (dist_slot >= DIST_MODEL_START) {
+		const uint32_t footer_bits = (dist_slot >> 1) - 1;
+		const uint32_t base = (2 | (dist_slot & 1)) << footer_bits;
+		const uint32_t dist_reduced = distance - base;
+
+		if (dist_slot < DIST_MODEL_END) {
+			// Careful here: base - dist_slot - 1 can be -1, but
 			// rc_bittree_reverse starts at probs[1], not probs[0].
 			rc_bittree_reverse(&coder->rc,
-				coder->pos_special + base - pos_slot - 1,
-				footer_bits, pos_reduced);
+				coder->dist_special + base - dist_slot - 1,
+				footer_bits, dist_reduced);
 		} else {
-			rc_direct(&coder->rc, pos_reduced >> ALIGN_BITS,
+			rc_direct(&coder->rc, dist_reduced >> ALIGN_BITS,
 					footer_bits - ALIGN_BITS);
 			rc_bittree_reverse(
-					&coder->rc, coder->pos_align,
-					ALIGN_BITS, pos_reduced & ALIGN_MASK);
+					&coder->rc, coder->dist_align,
+					ALIGN_BITS, dist_reduced & ALIGN_MASK);
 			++coder->align_price_count;
 		}
 	}
@@ -247,7 +247,7 @@ encode_symbol(lzma_coder *coder, lzma_mf *mf,
 		rc_bit(&coder->rc,
 			&coder->is_match[coder->state][pos_state], 1);
 
-		if (back < REP_DISTANCES) {
+		if (back < REPS) {
 			// It's a repeated match i.e. the same distance
 			// has been used earlier.
 			rc_bit(&coder->rc, &coder->is_rep[coder->state], 1);
@@ -255,7 +255,7 @@ encode_symbol(lzma_coder *coder, lzma_mf *mf,
 		} else {
 			// Normal match
 			rc_bit(&coder->rc, &coder->is_rep[coder->state], 0);
-			match(coder, pos_state, back - REP_DISTANCES, len);
+			match(coder, pos_state, back - REPS, len);
 		}
 	}
 
@@ -353,9 +353,9 @@ lzma_lzma_encode(lzma_coder *restrict coder, lzma_mf *restrict mf,
 
 		// Get optimal match (repeat position and length).
 		// Value ranges for pos:
-		//   - [0, REP_DISTANCES): repeated match
-		//   - [REP_DISTANCES, UINT32_MAX):
-		//     match at (pos - REP_DISTANCES)
+		//   - [0, REPS): repeated match
+		//   - [REPS, UINT32_MAX):
+		//     match at (pos - REPS)
 		//   - UINT32_MAX: not a match but a literal
 		// Value ranges for len:
 		//   - [MATCH_LEN_MIN, MATCH_LEN_MAX]
@@ -487,7 +487,7 @@ lzma_lzma_encoder_reset(lzma_coder *coder, const lzma_options_lzma *options)
 
 	// State
 	coder->state = STATE_LIT_LIT;
-	for (size_t i = 0; i < REP_DISTANCES; ++i)
+	for (size_t i = 0; i < REPS; ++i)
 		coder->reps[i] = 0;
 
 	literal_init(coder->literal, options->lc, options->lp);
@@ -505,14 +505,14 @@ lzma_lzma_encoder_reset(lzma_coder *coder, const lzma_options_lzma *options)
 		bit_reset(coder->is_rep2[i]);
 	}
 
-	for (size_t i = 0; i < FULL_DISTANCES - END_POS_MODEL_INDEX; ++i)
-		bit_reset(coder->pos_special[i]);
+	for (size_t i = 0; i < FULL_DISTANCES - DIST_MODEL_END; ++i)
+		bit_reset(coder->dist_special[i]);
 
 	// Bit tree encoders
-	for (size_t i = 0; i < LEN_TO_POS_STATES; ++i)
-		bittree_reset(coder->pos_slot[i], POS_SLOT_BITS);
+	for (size_t i = 0; i < DIST_STATES; ++i)
+		bittree_reset(coder->dist_slot[i], DIST_SLOT_BITS);
 
-	bittree_reset(coder->pos_align, ALIGN_BITS);
+	bittree_reset(coder->dist_align, ALIGN_BITS);
 
 	// Length encoders
 	length_encoder_reset(&coder->match_len_encoder,
diff --git a/src/liblzma/lzma/lzma_encoder_optimum_fast.c b/src/liblzma/lzma/lzma_encoder_optimum_fast.c
index f835f693..92bbdf79 100644
--- a/src/liblzma/lzma/lzma_encoder_optimum_fast.c
+++ b/src/liblzma/lzma/lzma_encoder_optimum_fast.c
@@ -46,7 +46,7 @@ lzma_lzma_optimum_fast(lzma_coder *restrict coder, lzma_mf *restrict mf,
 	uint32_t rep_len = 0;
 	uint32_t rep_index = 0;
 
-	for (uint32_t i = 0; i < REP_DISTANCES; ++i) {
+	for (uint32_t i = 0; i < REPS; ++i) {
 		// Pointer to the beginning of the match candidate
 		const uint8_t *const buf_back = buf - coder->reps[i] - 1;
 
@@ -79,8 +79,7 @@ lzma_lzma_optimum_fast(lzma_coder *restrict coder, lzma_mf *restrict mf,
 	// We didn't find a long enough repeated match. Encode it as a normal
 	// match if the match length is at least nice_len.
 	if (len_main >= nice_len) {
-		*back_res = coder->matches[matches_count - 1].dist
-				+ REP_DISTANCES;
+		*back_res = coder->matches[matches_count - 1].dist + REPS;
 		*len_res = len_main;
 		mf_skip(mf, len_main - 1);
 		return;
@@ -155,7 +154,7 @@ lzma_lzma_optimum_fast(lzma_coder *restrict coder, lzma_mf *restrict mf,
 
 	const uint32_t limit = len_main - 1;
 
-	for (uint32_t i = 0; i < REP_DISTANCES; ++i) {
+	for (uint32_t i = 0; i < REPS; ++i) {
 		const uint8_t *const buf_back = buf - coder->reps[i] - 1;
 
 		if (not_equal_16(buf, buf_back))
@@ -172,7 +171,7 @@ lzma_lzma_optimum_fast(lzma_coder *restrict coder, lzma_mf *restrict mf,
 		}
 	}
 
-	*back_res = back_main + REP_DISTANCES;
+	*back_res = back_main + REPS;
 	*len_res = len_main;
 	mf_skip(mf, len_main - 2);
 	return;
diff --git a/src/liblzma/lzma/lzma_encoder_optimum_normal.c b/src/liblzma/lzma/lzma_encoder_optimum_normal.c
index 7e856493..0dd5f73d 100644
--- a/src/liblzma/lzma/lzma_encoder_optimum_normal.c
+++ b/src/liblzma/lzma/lzma_encoder_optimum_normal.c
@@ -108,18 +108,18 @@ get_rep_price(const lzma_coder *const coder, const uint32_t rep_index,
 
 
 static inline uint32_t
-get_pos_len_price(const lzma_coder *const coder, const uint32_t pos,
+get_dist_len_price(const lzma_coder *const coder, const uint32_t dist,
 		const uint32_t len, const uint32_t pos_state)
 {
-	const uint32_t len_to_pos_state = get_len_to_pos_state(len);
+	const uint32_t dist_state = get_dist_state(len);
 	uint32_t price;
 
-	if (pos < FULL_DISTANCES) {
-		price = coder->distances_prices[len_to_pos_state][pos];
+	if (dist < FULL_DISTANCES) {
+		price = coder->dist_prices[dist_state][dist];
 	} else {
-		const uint32_t pos_slot = get_pos_slot_2(pos);
-		price = coder->pos_slot_prices[len_to_pos_state][pos_slot]
-				+ coder->align_prices[pos & ALIGN_MASK];
+		const uint32_t dist_slot = get_dist_slot_2(dist);
+		price = coder->dist_slot_prices[dist_state][dist_slot]
+				+ coder->align_prices[dist & ALIGN_MASK];
 	}
 
 	price += get_len_price(&coder->match_len_encoder, len, pos_state);
@@ -129,55 +129,53 @@ get_pos_len_price(const lzma_coder *const coder, const uint32_t pos,
 
 
 static void
-fill_distances_prices(lzma_coder *coder)
+fill_dist_prices(lzma_coder *coder)
 {
-	for (uint32_t len_to_pos_state = 0;
-			len_to_pos_state < LEN_TO_POS_STATES;
-			++len_to_pos_state) {
+	for (uint32_t dist_state = 0; dist_state < DIST_STATES; ++dist_state) {
 
-		uint32_t *const pos_slot_prices
-				= coder->pos_slot_prices[len_to_pos_state];
+		uint32_t *const dist_slot_prices
+				= coder->dist_slot_prices[dist_state];
 
-		// Price to encode the pos_slot.
-		for (uint32_t pos_slot = 0;
-				pos_slot < coder->dist_table_size; ++pos_slot)
-			pos_slot_prices[pos_slot] = rc_bittree_price(
-					coder->pos_slot[len_to_pos_state],
-					POS_SLOT_BITS, pos_slot);
+		// Price to encode the dist_slot.
+		for (uint32_t dist_slot = 0;
+				dist_slot < coder->dist_table_size; ++dist_slot)
+			dist_slot_prices[dist_slot] = rc_bittree_price(
+					coder->dist_slot[dist_state],
+					DIST_SLOT_BITS, dist_slot);
 
 		// For matches with distance >= FULL_DISTANCES, add the price
 		// of the direct bits part of the match distance. (Align bits
 		// are handled by fill_align_prices()).
-		for (uint32_t pos_slot = END_POS_MODEL_INDEX;
-				pos_slot < coder->dist_table_size; ++pos_slot)
-			pos_slot_prices[pos_slot] += rc_direct_price(
-					((pos_slot >> 1) - 1) - ALIGN_BITS);
+		for (uint32_t dist_slot = DIST_MODEL_END;
+				dist_slot < coder->dist_table_size;
+				++dist_slot)
+			dist_slot_prices[dist_slot] += rc_direct_price(
+					((dist_slot >> 1) - 1) - ALIGN_BITS);
 
 		// Distances in the range [0, 3] are fully encoded with
-		// pos_slot, so they are used for coder->distances_prices
+		// dist_slot, so they are used for coder->dist_prices
 		// as is.
-		for (uint32_t i = 0; i < START_POS_MODEL_INDEX; ++i)
-			coder->distances_prices[len_to_pos_state][i]
-					= pos_slot_prices[i];
+		for (uint32_t i = 0; i < DIST_MODEL_START; ++i)
+			coder->dist_prices[dist_state][i]
+					= dist_slot_prices[i];
 	}
 
-	// Distances in the range [4, 127] depend on pos_slot and pos_special.
-	// We do this in a loop separate from the above loop to avoid
-	// redundant calls to get_pos_slot().
-	for (uint32_t i = START_POS_MODEL_INDEX; i < FULL_DISTANCES; ++i) {
-		const uint32_t pos_slot = get_pos_slot(i);
-		const uint32_t footer_bits = ((pos_slot >> 1) - 1);
-		const uint32_t base = (2 | (pos_slot & 1)) << footer_bits;
+	// Distances in the range [4, 127] depend on dist_slot and
+	// dist_special. We do this in a loop separate from the above
+	// loop to avoid redundant calls to get_dist_slot().
+	for (uint32_t i = DIST_MODEL_START; i < FULL_DISTANCES; ++i) {
+		const uint32_t dist_slot = get_dist_slot(i);
+		const uint32_t footer_bits = ((dist_slot >> 1) - 1);
+		const uint32_t base = (2 | (dist_slot & 1)) << footer_bits;
 		const uint32_t price = rc_bittree_reverse_price(
-				coder->pos_special + base - pos_slot - 1,
+				coder->dist_special + base - dist_slot - 1,
 				footer_bits, i - base);
 
-		for (uint32_t len_to_pos_state = 0;
-				len_to_pos_state < LEN_TO_POS_STATES;
-				++len_to_pos_state)
-			coder->distances_prices[len_to_pos_state][i]
-					= price + coder->pos_slot_prices[
-						len_to_pos_state][pos_slot];
+		for (uint32_t dist_state = 0; dist_state < DIST_STATES;
+				++dist_state)
+			coder->dist_prices[dist_state][i]
+					= price + coder->dist_slot_prices[
+						dist_state][dist_slot];
 	}
 
 	coder->match_price_count = 0;
@@ -188,9 +186,9 @@ fill_distances_prices(lzma_coder *coder)
 static void
 fill_align_prices(lzma_coder *coder)
 {
-	for (uint32_t i = 0; i < ALIGN_TABLE_SIZE; ++i)
+	for (uint32_t i = 0; i < ALIGN_SIZE; ++i)
 		coder->align_prices[i] = rc_bittree_reverse_price(
-				coder->pos_align, ALIGN_BITS, i);
+				coder->dist_align, ALIGN_BITS, i);
 
 	coder->align_price_count = 0;
 	return;
@@ -296,10 +294,10 @@ helper1(lzma_coder *restrict coder, lzma_mf *restrict mf,
 
 	const uint8_t *const buf = mf_ptr(mf) - 1;
 
-	uint32_t rep_lens[REP_DISTANCES];
+	uint32_t rep_lens[REPS];
 	uint32_t rep_max_index = 0;
 
-	for (uint32_t i = 0; i < REP_DISTANCES; ++i) {
+	for (uint32_t i = 0; i < REPS; ++i) {
 		const uint8_t *const buf_back = buf - coder->reps[i] - 1;
 
 		if (not_equal_16(buf, buf_back)) {
@@ -326,8 +324,7 @@ helper1(lzma_coder *restrict coder, lzma_mf *restrict mf,
 
 
 	if (len_main >= nice_len) {
-		*back_res = coder->matches[matches_count - 1].dist
-				+ REP_DISTANCES;
+		*back_res = coder->matches[matches_count - 1].dist + REPS;
 		*len_res = len_main;
 		mf_skip(mf, len_main - 1);
 		return UINT32_MAX;
@@ -381,7 +378,7 @@ helper1(lzma_coder *restrict coder, lzma_mf *restrict mf,
 
 	coder->opts[1].pos_prev = 0;
 
-	for (uint32_t i = 0; i < REP_DISTANCES; ++i)
+	for (uint32_t i = 0; i < REPS; ++i)
 		coder->opts[0].backs[i] = coder->reps[i];
 
 	uint32_t len = len_end;
@@ -390,7 +387,7 @@ helper1(lzma_coder *restrict coder, lzma_mf *restrict mf,
 	} while (--len >= 2);
 
 
-	for (uint32_t i = 0; i < REP_DISTANCES; ++i) {
+	for (uint32_t i = 0; i < REPS; ++i) {
 		uint32_t rep_len = rep_lens[i];
 		if (rep_len < 2)
 			continue;
@@ -426,14 +423,13 @@ helper1(lzma_coder *restrict coder, lzma_mf *restrict mf,
 		for(; ; ++len) {
 			const uint32_t dist = coder->matches[i].dist;
 			const uint32_t cur_and_len_price = normal_match_price
-					+ get_pos_len_price(coder,
+					+ get_dist_len_price(coder,
 						dist, len, pos_state);
 
 			if (cur_and_len_price < coder->opts[len].price) {
 				coder->opts[len].price = cur_and_len_price;
 				coder->opts[len].pos_prev = 0;
-				coder->opts[len].back_prev
-						= dist + REP_DISTANCES;
+				coder->opts[len].back_prev = dist + REPS;
 				coder->opts[len].prev_1_is_literal = false;
 			}
 
@@ -463,7 +459,7 @@ helper2(lzma_coder *coder, uint32_t *reps, const uint8_t *buf,
 		if (coder->opts[cur].prev_2) {
 			state = coder->opts[coder->opts[cur].pos_prev_2].state;
 
-			if (coder->opts[cur].back_prev_2 < REP_DISTANCES)
+			if (coder->opts[cur].back_prev_2 < REPS)
 				update_long_rep(state);
 			else
 				update_match(state);
@@ -492,33 +488,33 @@ helper2(lzma_coder *coder, uint32_t *reps, const uint8_t *buf,
 			update_long_rep(state);
 		} else {
 			pos = coder->opts[cur].back_prev;
-			if (pos < REP_DISTANCES)
+			if (pos < REPS)
 				update_long_rep(state);
 			else
 				update_match(state);
 		}
 
-		if (pos < REP_DISTANCES) {
+		if (pos < REPS) {
 			reps[0] = coder->opts[pos_prev].backs[pos];
 
 			uint32_t i;
 			for (i = 1; i <= pos; ++i)
 				reps[i] = coder->opts[pos_prev].backs[i - 1];
 
-			for (; i < REP_DISTANCES; ++i)
+			for (; i < REPS; ++i)
 				reps[i] = coder->opts[pos_prev].backs[i];
 
 		} else {
-			reps[0] = pos - REP_DISTANCES;
+			reps[0] = pos - REPS;
 
-			for (uint32_t i = 1; i < REP_DISTANCES; ++i)
+			for (uint32_t i = 1; i < REPS; ++i)
 				reps[i] = coder->opts[pos_prev].backs[i - 1];
 		}
 	}
 
 	coder->opts[cur].state = state;
 
-	for (uint32_t i = 0; i < REP_DISTANCES; ++i)
+	for (uint32_t i = 0; i < REPS; ++i)
 		coder->opts[cur].backs[i] = reps[i];
 
 	const uint32_t cur_price = coder->opts[cur].price;
@@ -611,7 +607,7 @@ helper2(lzma_coder *coder, uint32_t *reps, const uint8_t *buf,
 
 	uint32_t start_len = 2; // speed optimization
 
-	for (uint32_t rep_index = 0; rep_index < REP_DISTANCES; ++rep_index) {
+	for (uint32_t rep_index = 0; rep_index < REPS; ++rep_index) {
 		const uint8_t *const buf_back = buf - reps[rep_index] - 1;
 		if (not_equal_16(buf, buf_back))
 			continue;
@@ -728,14 +724,14 @@ helper2(lzma_coder *coder, uint32_t *reps, const uint8_t *buf,
 		for (uint32_t len_test = start_len; ; ++len_test) {
 			const uint32_t cur_back = coder->matches[i].dist;
 			uint32_t cur_and_len_price = normal_match_price
-					+ get_pos_len_price(coder,
+					+ get_dist_len_price(coder,
 						cur_back, len_test, pos_state);
 
 			if (cur_and_len_price < coder->opts[cur + len_test].price) {
 				coder->opts[cur + len_test].price = cur_and_len_price;
 				coder->opts[cur + len_test].pos_prev = cur;
 				coder->opts[cur + len_test].back_prev
-						= cur_back + REP_DISTANCES;
+						= cur_back + REPS;
 				coder->opts[cur + len_test].prev_1_is_literal = false;
 			}
 
@@ -795,7 +791,7 @@ helper2(lzma_coder *coder, uint32_t *reps, const uint8_t *buf,
 						coder->opts[offset].prev_2 = true;
 						coder->opts[offset].pos_prev_2 = cur;
 						coder->opts[offset].back_prev_2
-								= cur_back + REP_DISTANCES;
+								= cur_back + REPS;
 					}
 					//}
 				}
@@ -831,9 +827,9 @@ lzma_lzma_optimum_normal(lzma_coder *restrict coder, lzma_mf *restrict mf,
 	// In liblzma they were moved into this single place.
 	if (mf->read_ahead == 0) {
 		if (coder->match_price_count >= (1 << 7))
-			fill_distances_prices(coder);
+			fill_dist_prices(coder);
 
-		if (coder->align_price_count >= ALIGN_TABLE_SIZE)
+		if (coder->align_price_count >= ALIGN_SIZE)
 			fill_align_prices(coder);
 	}
 
@@ -845,7 +841,7 @@ lzma_lzma_optimum_normal(lzma_coder *restrict coder, lzma_mf *restrict mf,
 	if (len_end == UINT32_MAX)
 		return;
 
-	uint32_t reps[REP_DISTANCES];
+	uint32_t reps[REPS];
 	memcpy(reps, coder->reps, sizeof(reps));
 
 	uint32_t cur;
diff --git a/src/liblzma/lzma/lzma_encoder_private.h b/src/liblzma/lzma/lzma_encoder_private.h
index 68474523..2f62d6cb 100644
--- a/src/liblzma/lzma/lzma_encoder_private.h
+++ b/src/liblzma/lzma/lzma_encoder_private.h
@@ -64,7 +64,7 @@ typedef struct {
 	uint32_t pos_prev;  // pos_next;
 	uint32_t back_prev;
 
-	uint32_t backs[REP_DISTANCES];
+	uint32_t backs[REPS];
 
 } lzma_optimal;
 
@@ -77,7 +77,7 @@ struct lzma_coder_s {
 	lzma_lzma_state state;
 
 	/// The four most recent match distances
-	uint32_t reps[REP_DISTANCES];
+	uint32_t reps[REPS];
 
 	/// Array of match candidates
 	lzma_match matches[MATCH_LEN_MAX + 1];
@@ -112,9 +112,9 @@ struct lzma_coder_s {
 	probability is_rep1[STATES];
 	probability is_rep2[STATES];
 	probability is_rep0_long[STATES][POS_STATES_MAX];
-	probability pos_slot[LEN_TO_POS_STATES][POS_SLOTS];
-	probability pos_special[FULL_DISTANCES - END_POS_MODEL_INDEX];
-	probability pos_align[ALIGN_TABLE_SIZE];
+	probability dist_slot[DIST_STATES][DIST_SLOTS];
+	probability dist_special[FULL_DISTANCES - DIST_MODEL_END];
+	probability dist_align[ALIGN_SIZE];
 
 	// These are the same as in lzma_decoder.c except that the encoders
 	// include also price tables.
@@ -122,12 +122,12 @@ struct lzma_coder_s {
 	lzma_length_encoder rep_len_encoder;
 
 	// Price tables
-	uint32_t pos_slot_prices[LEN_TO_POS_STATES][POS_SLOTS];
-	uint32_t distances_prices[LEN_TO_POS_STATES][FULL_DISTANCES];
+	uint32_t dist_slot_prices[DIST_STATES][DIST_SLOTS];
+	uint32_t dist_prices[DIST_STATES][FULL_DISTANCES];
 	uint32_t dist_table_size;
 	uint32_t match_price_count;
 
-	uint32_t align_prices[ALIGN_TABLE_SIZE];
+	uint32_t align_prices[ALIGN_SIZE];
 	uint32_t align_price_count;
 
 	// Optimal