Add README and clean up code

contrib/long_distance_matching/ldm.h

@@ -2,7 +2,52 @@
 #define LDM_H
 
 #include "mem.h"    // from /lib/common/mem.h
-#include "ldm_params.h"
+
+// #include "ldm_params.h"
+
+// =============================================================================
+// Modify the parameters in ldm_params.h if "ldm_params.h" is included.
+// Otherwise, modify the parameters here.
+// =============================================================================
+
+#ifndef LDM_PARAMS_H
+  // Defines the size of the hash table.
+  // Note that this is not the number of buckets.
+  // Currently this should be less than WINDOW_SIZE_LOG + 4.
+  #define LDM_MEMORY_USAGE 23
+
+  // The number of entries in a hash bucket.
+  #define HASH_BUCKET_SIZE_LOG 3 // The maximum is 4 for now.
+
+  // Defines the lag in inserting elements into the hash table.
+  #define LDM_LAG 0
+
+  // The maximum window size when searching for matches.
+  // The maximum value is 30.
+  #define LDM_WINDOW_SIZE_LOG 28
+
+  // The minimum match length.
+  // This should be a multiple of four.
+  #define LDM_MIN_MATCH_LENGTH 64
+
+  // If INSERT_BY_TAG, insert entries into the hash table as a function of the
+  // hash. Certain hashes will not be inserted.
+  //
+  // Otherwise, insert as a function of the position.
+  #define INSERT_BY_TAG 1
+
+  // Store a checksum with the hash table entries for faster comparison.
+  // This halves the number of entries the hash table can contain.
+  #define USE_CHECKSUM 1
+#endif
+
+// Output compression statistics.
+#define COMPUTE_STATS
+
+// Output the configuration.
+#define OUTPUT_CONFIGURATION
+
+// =============================================================================
 
 // The number of bytes storing the compressed and decompressed size
 // in the header.
@@ -15,40 +60,9 @@
 #define RUN_BITS (8-ML_BITS)
 #define RUN_MASK ((1U<<RUN_BITS)-1)
 
-// THe number of bytes storing the offset.
+// The number of bytes storing the offset.
 #define LDM_OFFSET_SIZE 4
 
-// =============================================================================
-// Modify parameters in ldm_params.h if "ldm_params.h" is included.
-// =============================================================================
-
-#ifndef LDM_PARAMS_H
-// Defines the size of the hash table.
-// Note that this is not the number of buckets.
-// Currently this should be less than WINDOW_SIZE_LOG + 4?
-  #define LDM_MEMORY_USAGE 25
-
-// The number of entries in a hash bucket.
-  #define HASH_BUCKET_SIZE_LOG 3 // The maximum is 4 for now.
-
-// Defines the lag in inserting elements into the hash table.
-  #define LDM_LAG 0
-
-// The maximum window size.
-  #define LDM_WINDOW_SIZE_LOG 28 // Max value is 30
-
-//These should be multiples of four (and perhaps set to the same value?).
-  #define LDM_MIN_MATCH_LENGTH 64
-
-  #define INSERT_BY_TAG 1 // Insertion policy based on hash.
-
-  #define USE_CHECKSUM 1
-#endif
-
-// =============================================================================
-#define COMPUTE_STATS
-#define OUTPUT_CONFIGURATION
-
 #define LDM_WINDOW_SIZE (1 << (LDM_WINDOW_SIZE_LOG))
 #define LDM_HASH_LENGTH LDM_MIN_MATCH_LENGTH
 
@@ -81,7 +95,6 @@ typedef struct LDM_DCtx LDM_DCtx;
  *  bytes added similarly to the additional literal length bytes after the offset.
  *
  *  The last sequence is incomplete and stops right after the literals.
- *
  */
 size_t LDM_compress(const void *src, size_t srcSize,
                     void *dst, size_t maxDstSize);
@@ -96,7 +109,7 @@ void LDM_initializeCCtx(LDM_CCtx *cctx,
                         void *dst, size_t maxDstSize);
 
 /**
- * Frees up memory allocating in initializeCCtx
+ * Frees up memory allocated in LDM_initializeCCtx().
  */
 void LDM_destroyCCtx(LDM_CCtx *cctx);
 
@@ -121,8 +134,8 @@ void LDM_printCompressStats(const LDM_compressStats *stats);
  *
  * This is followed by literalLength bytes corresponding to the literals.
  */
-void LDM_encodeLiteralLengthAndLiterals(
-    LDM_CCtx *cctx, BYTE *pToken, const U64 literalLength);
+void LDM_encodeLiteralLengthAndLiterals(LDM_CCtx *cctx, BYTE *pToken,
+                                        const U64 literalLength);
 
 /**
  * Write current block (literals, literal length, match offset,