ZSTD_maxCLevel() is promoted to "stable" API (#254, by @FrancescAlted)

lib/compress/zstd_compress.c

@@ -2767,7 +2767,7 @@ ZSTDLIB_API size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx,
 
 #define ZSTD_DEFAULT_CLEVEL 1
 #define ZSTD_MAX_CLEVEL     22
-unsigned ZSTD_maxCLevel(void) { return ZSTD_MAX_CLEVEL; }
+int ZSTD_maxCLevel(void) { return ZSTD_MAX_CLEVEL; }
 
 static const ZSTD_compressionParameters ZSTD_defaultCParameters[4][ZSTD_MAX_CLEVEL+1] = {
 {   /* "default" */

lib/dictBuilder/zdict.c

@@ -85,7 +85,7 @@
 #define PRIME2   2246822519U
 
 #define MINRATIO 4
-static const U32 g_compressionLevel_default = 5;
+static const int g_compressionLevel_default = 5;
 static const U32 g_selectivity_default = 9;
 static const size_t g_provision_entropySize = 200;
 static const size_t g_min_fast_dictContent = 192;
@@ -841,7 +841,7 @@ size_t ZDICT_addEntropyTablesFromBuffer_advanced(void* dictBuffer, size_t dictCo
                                                  ZDICT_params_t params)
 {
     size_t hSize;
-    unsigned const compressionLevel = (params.compressionLevel == 0) ? g_compressionLevel_default : params.compressionLevel;
+    int const compressionLevel = (params.compressionLevel <= 0) ? g_compressionLevel_default : params.compressionLevel;
 
     /* dictionary header */
     MEM_writeLE32(dictBuffer, ZSTD_DICT_MAGIC);

lib/dictBuilder/zdict.h

@@ -86,7 +86,7 @@ const char* ZDICT_getErrorName(size_t errorCode);
 
 typedef struct {
     unsigned selectivityLevel;   /* 0 means default; larger => bigger selection => larger dictionary */
-    unsigned compressionLevel;   /* 0 means default; target a specific zstd compression level */
+    int      compressionLevel;   /* 0 means default; target a specific zstd compression level */
     unsigned notificationLevel;  /* Write to stderr; 0 = none (default); 1 = errors; 2 = progression; 3 = details; 4 = debug; */
     unsigned dictID;             /* 0 means auto mode (32-bits random value); other : force dictID value */
     unsigned reserved[2];        /* space for future parameters */

lib/zstd.h

@@ -93,8 +93,10 @@ unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize);
 ZSTDLIB_API size_t ZSTD_decompress( void* dst, size_t dstCapacity,
                               const void* src, size_t compressedSize);
 
+
 /*======  Helper functions  ======*/
-ZSTDLIB_API size_t      ZSTD_compressBound(size_t srcSize); /*!< maximum compressed size (worst case scenario) */
+ZSTDLIB_API int         ZSTD_maxCLevel(void);               /*!< maximum compression level available */
+ZSTDLIB_API size_t      ZSTD_compressBound(size_t srcSize); /*!< maximum compressed size in worst case scenario */
 ZSTDLIB_API unsigned    ZSTD_isError(size_t code);          /*!< tells if a `size_t` function result is an error code */
 ZSTDLIB_API const char* ZSTD_getErrorName(size_t code);     /*!< provides readable string from an error code */
 
@@ -264,8 +266,6 @@ ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictS
  *  Gives the amount of memory used by a given ZSTD_CCtx */
 ZSTDLIB_API size_t ZSTD_sizeofCCtx(const ZSTD_CCtx* cctx);
 
-ZSTDLIB_API unsigned ZSTD_maxCLevel (void);
-
 /*! ZSTD_getParams() :
 *   same as ZSTD_getCParams(), but @return a full `ZSTD_parameters` object instead of a `ZSTD_compressionParameters`.
 *   All fields of `ZSTD_frameParameters` are set to default (0) */