Update Zstandard to v1.3.7

C/zstd/bitstream.h

@@ -339,17 +339,10 @@ MEM_STATIC size_t BIT_getUpperBits(size_t bitContainer, U32 const start)
 
 MEM_STATIC size_t BIT_getMiddleBits(size_t bitContainer, U32 const start, U32 const nbBits)
 {
-#if defined(__BMI__) && defined(__GNUC__) && __GNUC__*1000+__GNUC_MINOR__ >= 4008  /* experimental */
-#  if defined(__x86_64__)
-    if (sizeof(bitContainer)==8)
-        return _bextr_u64(bitContainer, start, nbBits);
-    else
-#  endif
-        return _bextr_u32(bitContainer, start, nbBits);
-#else
+    U32 const regMask = sizeof(bitContainer)*8 - 1;
+    /* if start > regMask, bitstream is corrupted, and result is undefined */
     assert(nbBits < BIT_MASK_SIZE);
-    return (bitContainer >> start) & BIT_mask[nbBits];
-#endif
+    return (bitContainer >> (start & regMask)) & BIT_mask[nbBits];
 }
 
 MEM_STATIC size_t BIT_getLowerBits(size_t bitContainer, U32 const nbBits)
@@ -366,9 +359,13 @@ MEM_STATIC size_t BIT_getLowerBits(size_t bitContainer, U32 const nbBits)
  * @return : value extracted */
 MEM_STATIC size_t BIT_lookBits(const BIT_DStream_t* bitD, U32 nbBits)
 {
-#if defined(__BMI__) && defined(__GNUC__)   /* experimental; fails if bitD->bitsConsumed + nbBits > sizeof(bitD->bitContainer)*8 */
+    /* arbitrate between double-shift and shift+mask */
+#if 1
+    /* if bitD->bitsConsumed + nbBits > sizeof(bitD->bitContainer)*8,
+     * bitstream is likely corrupted, and result is undefined */
     return BIT_getMiddleBits(bitD->bitContainer, (sizeof(bitD->bitContainer)*8) - bitD->bitsConsumed - nbBits, nbBits);
 #else
+    /* this code path is slower on my os-x laptop */
     U32 const regMask = sizeof(bitD->bitContainer)*8 - 1;
     return ((bitD->bitContainer << (bitD->bitsConsumed & regMask)) >> 1) >> ((regMask-nbBits) & regMask);
 #endif

C/zstd/mem.h

@@ -39,6 +39,10 @@ extern "C" {
 #  define MEM_STATIC static  /* this version may generate warnings for unused static functions; disable the relevant warning */
 #endif
 
+#ifndef __has_builtin
+#  define __has_builtin(x) 0  /* compat. with non-clang compilers */
+#endif
+
 /* code only tested on 32 and 64 bits systems */
 #define MEM_STATIC_ASSERT(c)   { enum { MEM_static_assert = 1/(int)(!!(c)) }; }
 MEM_STATIC void MEM_check(void) { MEM_STATIC_ASSERT((sizeof(size_t)==4) || (sizeof(size_t)==8)); }
@@ -198,7 +202,8 @@ MEM_STATIC U32 MEM_swap32(U32 in)
 {
 #if defined(_MSC_VER)     /* Visual Studio */
     return _byteswap_ulong(in);
-#elif defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403)
+#elif (defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403)) \
+  || (defined(__clang__) && __has_builtin(__builtin_bswap32))
     return __builtin_bswap32(in);
 #else
     return  ((in << 24) & 0xff000000 ) |
@@ -212,7 +217,8 @@ MEM_STATIC U64 MEM_swap64(U64 in)
 {
 #if defined(_MSC_VER)     /* Visual Studio */
     return _byteswap_uint64(in);
-#elif defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403)
+#elif (defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403)) \
+  || (defined(__clang__) && __has_builtin(__builtin_bswap64))
     return __builtin_bswap64(in);
 #else
     return  ((in << 56) & 0xff00000000000000ULL) |

C/zstd/zstd.h

@@ -71,7 +71,7 @@ extern "C" {
 /*------   Version   ------*/
 #define ZSTD_VERSION_MAJOR    1
 #define ZSTD_VERSION_MINOR    3
-#define ZSTD_VERSION_RELEASE  6
+#define ZSTD_VERSION_RELEASE  7
 
 #define ZSTD_VERSION_NUMBER  (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE)
 ZSTDLIB_API unsigned ZSTD_versionNumber(void);   /**< useful to check dll version */
@@ -361,15 +361,21 @@ ZSTDLIB_API size_t ZSTD_CStreamOutSize(void);   /**< recommended size for output
 *  The function will update both `pos` fields.
 *  If `input.pos < input.size`, some input has not been consumed.
 *  It's up to the caller to present again remaining data.
+*  The function tries to flush all data decoded immediately, repecting buffer sizes.
 *  If `output.pos < output.size`, decoder has flushed everything it could.
-*  @return : 0 when a frame is completely decoded and fully flushed,
-*            an error code, which can be tested using ZSTD_isError(),
-*            any other value > 0, which means there is still some decoding to do to complete current frame.
-*            The return value is a suggested next input size (a hint to improve latency) that will never load more than the current frame.
+*  But if `output.pos == output.size`, there is no such guarantee,
+*  it's likely that some decoded data was not flushed and still remains within internal buffers.
+*  In which case, call ZSTD_decompressStream() again to flush whatever remains in the buffer.
+*  When no additional input is provided, amount of data flushed is necessarily <= ZSTD_BLOCKSIZE_MAX.
+* @return : 0 when a frame is completely decoded and fully flushed,
+*        or an error code, which can be tested using ZSTD_isError(),
+*        or any other value > 0, which means there is still some decoding or flushing to do to complete current frame :
+*                                the return value is a suggested next input size (a hint for better latency)
+*                                that will never load more than the current frame.
 * *******************************************************************************/
 
 typedef ZSTD_DCtx ZSTD_DStream;  /**< DCtx and DStream are now effectively same object (>= v1.3.0) */
-                                 /* For compatibility with versions <= v1.2.0, continue to consider them separated. */
+                                 /* For compatibility with versions <= v1.2.0, prefer differentiating them. */
 /*===== ZSTD_DStream management functions =====*/
 ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream(void);
 ZSTDLIB_API size_t ZSTD_freeDStream(ZSTD_DStream* zds);
@@ -1235,9 +1241,13 @@ ZSTDLIB_API size_t ZSTD_CCtx_resetParameters(ZSTD_CCtx* cctx);
 
 
 typedef enum {
-    ZSTD_e_continue=0, /* collect more data, encoder decides when to output compressed result, for optimal conditions */
-    ZSTD_e_flush,      /* flush any data provided so far - frame will continue, future data can still reference previous data for better compression */
-    ZSTD_e_end         /* flush any remaining data and close current frame. Any additional data starts a new frame. */
+    ZSTD_e_continue=0, /* collect more data, encoder decides when to output compressed result, for optimal compression ratio */
+    ZSTD_e_flush,      /* flush any data provided so far,
+                        * it creates (at least) one new block, that can be decoded immediately on reception;
+                        * frame will continue: any future data can still reference previously compressed data, improving compression. */
+    ZSTD_e_end         /* flush any remaining data and close current frame.
+                        * any additional data starts a new frame.
+                        * each frame is independent (does not reference any content from previous frame). */
 } ZSTD_EndDirective;
 
 /*! ZSTD_compress_generic() :

C/zstd/zstd_lazy.c

@@ -147,6 +147,7 @@ ZSTD_DUBT_findBetterDictMatch (
         ZSTD_matchState_t* ms,
         const BYTE* const ip, const BYTE* const iend,
         size_t* offsetPtr,
+        size_t bestLength,
         U32 nbCompares,
         U32 const mls,
         const ZSTD_dictMode_e dictMode)
@@ -172,8 +173,7 @@ ZSTD_DUBT_findBetterDictMatch (
     U32         const btMask = (1 << btLog) - 1;
     U32         const btLow = (btMask >= dictHighLimit - dictLowLimit) ? dictLowLimit : dictHighLimit - btMask;
 
-    size_t commonLengthSmaller=0, commonLengthLarger=0, bestLength=0;
-    U32 matchEndIdx = current+8+1;
+    size_t commonLengthSmaller=0, commonLengthLarger=0;
 
     (void)dictMode;
     assert(dictMode == ZSTD_dictMatchState);
@@ -188,10 +188,8 @@ ZSTD_DUBT_findBetterDictMatch (
 
         if (matchLength > bestLength) {
             U32 matchIndex = dictMatchIndex + dictIndexDelta;
-            if (matchLength > matchEndIdx - matchIndex)
-                matchEndIdx = matchIndex + (U32)matchLength;
             if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(current-matchIndex+1) - ZSTD_highbit32((U32)offsetPtr[0]+1)) ) {
-                DEBUGLOG(2, "ZSTD_DUBT_findBestDictMatch(%u) : found better match length %u -> %u and offsetCode %u -> %u (dictMatchIndex %u, matchIndex %u)",
+                DEBUGLOG(9, "ZSTD_DUBT_findBetterDictMatch(%u) : found better match length %u -> %u and offsetCode %u -> %u (dictMatchIndex %u, matchIndex %u)",
                     current, (U32)bestLength, (U32)matchLength, (U32)*offsetPtr, ZSTD_REP_MOVE + current - matchIndex, dictMatchIndex, matchIndex);
                 bestLength = matchLength, *offsetPtr = ZSTD_REP_MOVE + current - matchIndex;
             }
@@ -200,7 +198,6 @@ ZSTD_DUBT_findBetterDictMatch (
             }
         }
 
-        DEBUGLOG(2, "matchLength:%6zu, match:%p, prefixStart:%p, ip:%p", matchLength, match, prefixStart, ip);
         if (match[matchLength] < ip[matchLength]) {
             if (dictMatchIndex <= btLow) { break; }   /* beyond tree size, stop the search */
             commonLengthSmaller = matchLength;    /* all smaller will now have at least this guaranteed common length */
@@ -215,7 +212,7 @@ ZSTD_DUBT_findBetterDictMatch (
 
     if (bestLength >= MINMATCH) {
         U32 const mIndex = current - ((U32)*offsetPtr - ZSTD_REP_MOVE); (void)mIndex;
-        DEBUGLOG(2, "ZSTD_DUBT_findBestDictMatch(%u) : found match of length %u and offsetCode %u (pos %u)",
+        DEBUGLOG(8, "ZSTD_DUBT_findBetterDictMatch(%u) : found match of length %u and offsetCode %u (pos %u)",
                     current, (U32)bestLength, (U32)*offsetPtr, mIndex);
     }
     return bestLength;
@@ -323,6 +320,11 @@ ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms,
                 if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(current-matchIndex+1) - ZSTD_highbit32((U32)offsetPtr[0]+1)) )
                     bestLength = matchLength, *offsetPtr = ZSTD_REP_MOVE + current - matchIndex;
                 if (ip+matchLength == iend) {   /* equal : no way to know if inf or sup */
+                    if (dictMode == ZSTD_dictMatchState) {
+                        nbCompares = 0; /* in addition to avoiding checking any
+                                         * further in this loop, make sure we
+                                         * skip checking in the dictionary. */
+                    }
                     break;   /* drop, to guarantee consistency (miss a little bit of compression) */
                 }
             }
@@ -346,7 +348,10 @@ ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms,
         *smallerPtr = *largerPtr = 0;
 
         if (dictMode == ZSTD_dictMatchState && nbCompares) {
-            bestLength = ZSTD_DUBT_findBetterDictMatch(ms, ip, iend, offsetPtr, nbCompares, mls, dictMode);
+            bestLength = ZSTD_DUBT_findBetterDictMatch(
+                    ms, ip, iend,
+                    offsetPtr, bestLength, nbCompares,
+                    mls, dictMode);
         }
 
         assert(matchEndIdx > current+8); /* ensure nextToUpdate is increased */

README.md

@@ -15,7 +15,7 @@ You can install it in two ways:
 
 
 ## Codec overview
-1. [Zstandard] v1.3.6 is a real-time compression algorithm, providing high compression ratios. It offers a very wide range of compression / speed trade-off, while being backed by a very fast decoder.
+1. [Zstandard] v1.3.7 is a real-time compression algorithm, providing high compression ratios. It offers a very wide range of compression / speed trade-off, while being backed by a very fast decoder.
    - Levels: 1..22
 
 2. [Brotli] v.1.0.6 is a generic-purpose lossless compression algorithm that compresses data using a combination of a modern variant of the LZ77 algorithm, Huffman coding and 2nd order context modeling, with a compression ratio comparable to the best currently available general-purpose compression methods. It is similar in speed with deflate but offers more dense compression.
@@ -44,7 +44,7 @@ You can install it in two ways:
 
 The output should look like this:
 ```
-7-Zip 18.05 ZS v1.3.6 R1 (x64) : Copyright (c) 1999-2017 Igor Pavlov : 2018-10-21
+7-Zip 18.05 ZS v1.3.7 R1 (x64) : Copyright (c) 1999-2017 Igor Pavlov : 2018-10-21
 
 
 Libs:
@@ -253,7 +253,7 @@ You find this project useful, maybe you consider a donation ;-)
   - [Lizard] Version 1.0
   - [LZ4] Version 1.8.3
   - [LZ5] Version 1.5
-  - [Zstandard] Version 1.3.6
+  - [Zstandard] Version 1.3.7
 
 /TR 2018-10-21