added ZSTD_clampCParams()

now ZSTD_adjustCParams() is always successful,
it always produces a valid CParams

lib/compress/zstd_compress.c

@@ -433,8 +433,8 @@ void ZSTD_CCtx_reset(ZSTD_CCtx* cctx)
     cctx->cdict = NULL;
 }
 
-/** ZSTD_checkParams() :
+/** ZSTD_checkCParams() :
-    ensure param values remain within authorized range.
+    control CParam values remain within authorized range.
     @return : 0, or an error code if one value is beyond authorized range */
 size_t ZSTD_checkCParams(ZSTD_compressionParameters cParams)
 {
@@ -448,6 +448,25 @@ size_t ZSTD_checkCParams(ZSTD_compressionParameters cParams)
     return 0;
 }
 
+/** ZSTD_clampCParams() :
+ *  make CParam values within valid range.
+ *  @return : valid CParams */
+static ZSTD_compressionParameters ZSTD_clampCParams(ZSTD_compressionParameters cParams)
+{
+#   define CLAMP(val,min,max) {      \
+        if (val<min) val=min;        \
+        else if (val>max) val=max;   \
+    }
+    CLAMP(cParams.windowLog, ZSTD_WINDOWLOG_MIN, ZSTD_WINDOWLOG_MAX);
+    CLAMP(cParams.chainLog, ZSTD_CHAINLOG_MIN, ZSTD_CHAINLOG_MAX);
+    CLAMP(cParams.hashLog, ZSTD_HASHLOG_MIN, ZSTD_HASHLOG_MAX);
+    CLAMP(cParams.searchLog, ZSTD_SEARCHLOG_MIN, ZSTD_SEARCHLOG_MAX);
+    CLAMP(cParams.searchLength, ZSTD_SEARCHLENGTH_MIN, ZSTD_SEARCHLENGTH_MAX);
+    CLAMP(cParams.targetLength, ZSTD_TARGETLENGTH_MIN, ZSTD_TARGETLENGTH_MAX);
+    if ((U32)(cParams.strategy) > (U32)ZSTD_btultra) cParams.strategy = ZSTD_btultra;
+    return cParams;
+}
+
 /** ZSTD_cycleLog() :
  *  condition for correct operation : hashLog > 1 */
 static U32 ZSTD_cycleLog(U32 hashLog, ZSTD_strategy strat)
@@ -456,14 +475,15 @@ static U32 ZSTD_cycleLog(U32 hashLog, ZSTD_strategy strat)
     return hashLog - btScale;
 }
 
-/** ZSTD_adjustCParams() :
+/** ZSTD_adjustCParams_internal() :
     optimize `cPar` for a given input (`srcSize` and `dictSize`).
     mostly downsizing to reduce memory consumption and initialization.
     Both `srcSize` and `dictSize` are optional (use 0 if unknown),
     but if both are 0, no optimization can be done.
     Note : cPar is considered validated at this stage. Use ZSTD_checkParams() to ensure that. */
-ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, unsigned long long srcSize, size_t dictSize)
+ZSTD_compressionParameters ZSTD_adjustCParams_internal(ZSTD_compressionParameters cPar, unsigned long long srcSize, size_t dictSize)
 {
+    assert(ZSTD_checkCParams(cPar)==0);
     if (srcSize+dictSize == 0) return cPar;   /* no size information available : no adjustment */
 
     /* resize params, to use less memory when necessary */
@@ -483,6 +503,12 @@ ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, u
     return cPar;
 }
 
+ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, unsigned long long srcSize, size_t dictSize)
+{
+    cPar = ZSTD_clampCParams(cPar);
+    return ZSTD_adjustCParams_internal(cPar, srcSize, dictSize);
+}
+
 
 size_t ZSTD_estimateCCtxSize(ZSTD_compressionParameters cParams)
 {
@@ -3989,8 +4015,7 @@ ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long l
         if (cp.chainLog > ZSTD_CHAINLOG_MAX) cp.chainLog = ZSTD_CHAINLOG_MAX;
         if (cp.hashLog > ZSTD_HASHLOG_MAX) cp.hashLog = ZSTD_HASHLOG_MAX;
     }
-    cp = ZSTD_adjustCParams(cp, srcSizeHint, dictSize);
+    return ZSTD_adjustCParams_internal(cp, srcSizeHint, dictSize);   /* no need to ensure initial CParams validity */
-    return cp;
 }
 
 /*! ZSTD_getParams() :

lib/compress/zstdmt_compress.c

@@ -190,7 +190,7 @@ static ZSTDMT_CCtxPool* ZSTDMT_createCCtxPool(unsigned nbThreads,
     cctxPool->availCCtx = 1;   /* at least one cctx for single-thread mode */
     cctxPool->cctx[0] = ZSTD_createCCtx_advanced(cMem);
     if (!cctxPool->cctx[0]) { ZSTDMT_freeCCtxPool(cctxPool); return NULL; }
-    DEBUGLOG(1, "cctxPool created, with %u threads", nbThreads);
+    DEBUGLOG(3, "cctxPool created, with %u threads", nbThreads);
     return cctxPool;
 }
 
@@ -458,7 +458,7 @@ size_t ZSTDMT_compressCCtx(ZSTDMT_CCtx* mtctx,
     size_t frameStartPos = 0, dstBufferPos = 0;
 
     DEBUGLOG(3, "windowLog : %2u => chunkTargetSize : %u bytes  ", params.cParams.windowLog, (U32)chunkTargetSize);
-    DEBUGLOG(2, "nbChunks  : %2u   (chunkSize : %u bytes)   ", nbChunks, (U32)avgChunkSize);
+    DEBUGLOG(3, "nbChunks  : %2u   (chunkSize : %u bytes)   ", nbChunks, (U32)avgChunkSize);
     params.fParams.contentSizeFlag = 1;
 
     if (nbChunks==1) {   /* fallback to single-thread mode */

lib/zstd.h

@@ -589,8 +589,8 @@ ZSTDLIB_API ZSTD_parameters ZSTD_getParams(int compressionLevel, unsigned long l
 ZSTDLIB_API size_t ZSTD_checkCParams(ZSTD_compressionParameters params);
 
 /*! ZSTD_adjustCParams() :
-*   optimize params for a given `srcSize` and `dictSize`.
+ *  optimize params for a given `srcSize` and `dictSize`.
-*   both values are optional, select `0` if unknown. */
+ *  both values are optional, select `0` if unknown. */
 ZSTDLIB_API ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, unsigned long long srcSize, size_t dictSize);
 
 /*! ZSTD_compress_advanced() :