adding some debug functions to observe statistics

lib/compress/zstd_compress.c

@@ -1561,13 +1561,14 @@ void ZSTD_seqToCodes(const seqStore_t* seqStorePtr)
         mlCodeTable[seqStorePtr->longLengthPos] = MaxML;
 }
 
+
 typedef enum {
     ZSTD_defaultDisallowed = 0,
     ZSTD_defaultAllowed = 1
 } ZSTD_defaultPolicy_e;
 
-MEM_STATIC
-symbolEncodingType_e ZSTD_selectEncodingType(
+MEM_STATIC symbolEncodingType_e
+ZSTD_selectEncodingType(
             FSE_repeat* repeatMode, size_t const mostFrequent, size_t nbSeq,
             U32 defaultNormLog, ZSTD_defaultPolicy_e const isDefaultAllowed)
 {
@@ -1605,17 +1606,17 @@ symbolEncodingType_e ZSTD_selectEncodingType(
     return set_compressed;
 }
 
-MEM_STATIC
-size_t ZSTD_buildCTable(void* dst, size_t dstCapacity,
+MEM_STATIC size_t
+ZSTD_buildCTable(void* dst, size_t dstCapacity,
                 FSE_CTable* nextCTable, U32 FSELog, symbolEncodingType_e type,
                 U32* count, U32 max,
-        BYTE const* codeTable, size_t nbSeq,
-        S16 const* defaultNorm, U32 defaultNormLog, U32 defaultMax,
-        FSE_CTable const* prevCTable, size_t prevCTableSize,
+                const BYTE* codeTable, size_t nbSeq,
+                const S16* defaultNorm, U32 defaultNormLog, U32 defaultMax,
+                const FSE_CTable* prevCTable, size_t prevCTableSize,
                 void* workspace, size_t workspaceSize)
 {
     BYTE* op = (BYTE*)dst;
-    BYTE const* const oend = op + dstCapacity;
+    const BYTE* const oend = op + dstCapacity;
 
     switch (type) {
     case set_rle:
@@ -1917,9 +1918,9 @@ MEM_STATIC size_t ZSTD_compressSequences_internal(seqStore_t* seqStorePtr,
 }
 
 MEM_STATIC size_t ZSTD_compressSequences(seqStore_t* seqStorePtr,
-                              ZSTD_entropyCTables_t const* prevEntropy,
+                        const ZSTD_entropyCTables_t* prevEntropy,
                               ZSTD_entropyCTables_t* nextEntropy,
-                              ZSTD_CCtx_params const* cctxParams,
+                        const ZSTD_CCtx_params* cctxParams,
                               void* dst, size_t dstCapacity,
                               size_t srcSize, U32* workspace, int bmi2)
 {
@@ -1934,7 +1935,7 @@ MEM_STATIC size_t ZSTD_compressSequences(seqStore_t* seqStorePtr,
     if (ZSTD_isError(cSize)) return cSize;
 
     /* Check compressibility */
-    {   size_t const maxCSize = srcSize - ZSTD_minGain(srcSize);  /* note : fixed formula, maybe should depend on compression level, or strategy */
+    {   size_t const maxCSize = srcSize - ZSTD_minGain(srcSize);  /* note : fixed formula; to be refined, depending on compression level, or strategy */
         if (cSize >= maxCSize) return 0;  /* block not compressed */
     }
 

lib/compress/zstd_compress_internal.h

@@ -633,6 +633,33 @@ MEM_STATIC U32 ZSTD_window_update(ZSTD_window_t* window,
     return contiguous;
 }
 
+
+/* debug functions */
+
+MEM_STATIC double ZSTD_fWeight(U32 rawStat)
+{
+    U32 const fp_accuracy = 8;
+    U32 const fp_multiplier = (1 << fp_accuracy);
+    U32 const stat = rawStat + 1;
+    U32 const hb = ZSTD_highbit32(stat);
+    U32 const BWeight = hb * fp_multiplier;
+    U32 const FWeight = (stat << fp_accuracy) >> hb;
+    U32 const weight = BWeight + FWeight;
+    assert(hb + fp_accuracy < 31);
+    return (double)weight / fp_multiplier;
+}
+
+MEM_STATIC void ZSTD_debugTable(const U32* table, U32 max)
+{
+    unsigned u, sum;
+    for (u=0, sum=0; u<=max; u++) sum += table[u];
+    DEBUGLOG(2, "total nb elts: %u", sum);
+    for (u=0; u<=max; u++) {
+        DEBUGLOG(2, "%2u: %5u  (%.2f)",
+                u, table[u], ZSTD_fWeight(sum) - ZSTD_fWeight(table[u]) );
+    }
+}
+
 #if defined (__cplusplus)
 }
 #endif

lib/compress/zstd_opt.c

@@ -1057,7 +1057,6 @@ size_t ZSTD_compressBlock_btultra(
         /* re-inforce weight of collected statistics */
         ZSTD_upscaleStats(&ms->opt);
     }
-    DEBUGLOG(5, "base=%p,  src=%p,  src-base=%zi", ms->window.base, src, (const BYTE*)src - (const BYTE*)ms->window.base);
     return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, cParams, src, srcSize, 2 /*optLevel*/, 0 /*extDict*/);
 }