implemented ZSTD_dParam_getBounds()

and ZSTD_DCtx_setParameter()

lib/compress/zstd_compress.c

@@ -128,7 +128,7 @@ static size_t ZSTD_sizeof_mtctx(const ZSTD_CCtx* cctx)
 #ifdef ZSTD_MULTITHREAD
     return ZSTDMT_sizeof_CCtx(cctx->mtctx);
 #else
-    (void) cctx;
+    (void)cctx;
     return 0;
 #endif
 }

lib/decompress/zstd_decompress.c

@@ -1256,6 +1256,80 @@ size_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format)
     return 0;
 }
 
+ZSTD_bounds ZSTD_dParam_getBounds(ZSTD_dParameter dParam)
+{
+    ZSTD_bounds bounds = { 0, 0, 0 };
+    switch(dParam) {
+        case ZSTD_d_windowLogMax:
+            bounds.lowerBound = ZSTD_WINDOWLOG_ABSOLUTEMIN;
+            bounds.upperBound = ZSTD_WINDOWLOG_MAX;
+            return bounds;
+        case ZSTD_d_format:
+            bounds.lowerBound = (int)ZSTD_f_zstd1;
+            bounds.upperBound = (int)ZSTD_f_zstd1_magicless;
+            ZSTD_STATIC_ASSERT(ZSTD_f_zstd1 < ZSTD_f_zstd1_magicless);
+            return bounds;
+        default:
+            bounds.error = ERROR(parameter_unsupported);
+            return bounds;
+    }
+    assert(0);
+    bounds.error = ERROR(parameter_unsupported);
+    return bounds;
+}
+
+/* ZSTD_dParam_withinBounds:
+ * @return 1 if value is within dParam bounds,
+ * 0 otherwise */
+static int ZSTD_dParam_withinBounds(ZSTD_dParameter dParam, int value)
+{
+    ZSTD_bounds const bounds = ZSTD_dParam_getBounds(dParam);
+    if (ZSTD_isError(bounds.error)) return 0;
+    if (value < bounds.lowerBound) return 0;
+    if (value > bounds.upperBound) return 0;
+    return 1;
+}
+
+#define CHECK_DBOUNDS(p,v) {                \
+    if (!ZSTD_dParam_withinBounds(p, v))    \
+        return ERROR(parameter_outOfBound); \
+}
+
+size_t ZSTD_DCtx_setParameter(ZSTD_DCtx* dctx, ZSTD_dParameter dParam, int value)
+{
+    if (dctx->streamStage != zdss_init) return ERROR(stage_wrong);
+    switch(dParam) {
+        case ZSTD_d_windowLogMax:
+            CHECK_DBOUNDS(ZSTD_d_windowLogMax, value);
+            dctx->maxWindowSize = 1 << value;
+            return 0;
+        case ZSTD_d_format:
+            CHECK_DBOUNDS(ZSTD_d_format, value);
+            dctx->format = (ZSTD_format_e)value;
+            return 0;
+        default:
+            return ERROR(parameter_unsupported);
+    }
+    assert(0);  /* should be unreachable */
+    return ERROR(parameter_unsupported);
+}
+
+size_t ZSTD_DCtx_reset(ZSTD_DCtx* dctx, ZSTD_ResetDirective reset)
+{
+    if ( (reset == ZSTD_reset_session_only)
+      || (reset == ZSTD_reset_session_and_parameters) ) {
+        (void)ZSTD_initDStream(dctx);
+    }
+    if ( (reset == ZSTD_reset_parameters)
+      || (reset == ZSTD_reset_session_and_parameters) ) {
+        if (dctx->streamStage != zdss_init)
+            return ERROR(stage_wrong);
+        dctx->format = ZSTD_f_zstd1;
+        dctx->maxWindowSize = ZSTD_MAXWINDOWSIZE_DEFAULT;
+    }
+    return 0;
+}
+
 
 size_t ZSTD_sizeof_DStream(const ZSTD_DStream* dctx)
 {
@@ -1578,20 +1652,3 @@ size_t ZSTD_decompressStream_simpleArgs (
     *srcPos = input.pos;
     return cErr;
 }
-
-
-size_t ZSTD_DCtx_reset(ZSTD_DCtx* dctx, ZSTD_ResetDirective reset)
-{
-    if ( (reset == ZSTD_reset_session_only)
-      || (reset == ZSTD_reset_session_and_parameters) ) {
-        (void)ZSTD_initDStream(dctx);
-    }
-    if ( (reset == ZSTD_reset_parameters)
-      || (reset == ZSTD_reset_session_and_parameters) ) {
-        if (dctx->streamStage != zdss_init)
-            return ERROR(stage_wrong);
-        dctx->format = ZSTD_f_zstd1;
-        dctx->maxWindowSize = ZSTD_MAXWINDOWSIZE_DEFAULT;
-    }
-    return 0;
-}

lib/zstd.h

@@ -640,7 +640,7 @@ typedef struct {
  *  otherwise they will either trigger an error or be automatically clamped.
  * @return : a structure, ZSTD_bounds, which contains
  *         - an error status field, which must be tested using ZSTD_isError()
- *         - both lower and upper bounds, inclusive
+ *         - lower and upper bounds, both inclusive
  */
 ZSTDLIB_API ZSTD_bounds ZSTD_cParam_getBounds(ZSTD_cParameter cParam);
 
@@ -834,16 +834,16 @@ typedef enum {
  *         - an error status field, which must be tested using ZSTD_isError()
  *         - both lower and upper bounds, inclusive
  */
-ZSTDLIB_API ZSTD_bounds ZSTD_dParam_getBounds(ZSTD_dParameter dParam);    /* not implemented yet */
+ZSTDLIB_API ZSTD_bounds ZSTD_dParam_getBounds(ZSTD_dParameter dParam);
 
 /*! ZSTD_DCtx_setParameter() :
  *  Set one compression parameter, selected by enum ZSTD_dParameter.
  *  All parameters have valid bounds. Bounds can be queried using ZSTD_dParam_getBounds().
  *  Providing a value beyond bound will either clamp it, or trigger an error (depending on parameter).
  *  Setting a parameter is only possible during frame initialization (before starting decompression).
- * @return : an error code (which can be tested using ZSTD_isError()).
+ * @return : 0, or an error code (which can be tested using ZSTD_isError()).
  */
-ZSTDLIB_API size_t ZSTD_DCtx_setParameter(ZSTD_DCtx* dctx, ZSTD_dParameter param, int value);   /* not implemented yet */
+ZSTDLIB_API size_t ZSTD_DCtx_setParameter(ZSTD_DCtx* dctx, ZSTD_dParameter param, int value);
 
 
 /*! ZSTD_DCtx_loadDictionary() :
@@ -895,7 +895,7 @@ ZSTDLIB_API size_t ZSTD_DCtx_refPrefix(ZSTD_DCtx* dctx,
 
 /*! ZSTD_DCtx_reset() :
  *  Return a DCtx to clean state.
- *  Session and parameters can be reset jointly or separately
+ *  Session and parameters can be reset jointly or separately.
  *  Parameters can only be reset when no active frame is being decompressed.
  * @return : 0, or an error code, which can be tested with ZSTD_isError()
  */
@@ -1003,7 +1003,7 @@ typedef enum {
     ZSTD_f_zstd1 = 0,           /* zstd frame format, specified in zstd_compression_format.md (default) */
     ZSTD_f_zstd1_magicless = 1, /* Variant of zstd frame format, without initial 4-bytes magic number.
                                  * Useful to save 4 bytes per generated frame.
-                                 * Decoder cannot recognise automatically this format, requiring instructions. */
+                                 * Decoder cannot recognise automatically this format, requiring this instruction. */
 } ZSTD_format_e;
 
 typedef enum {
@@ -1440,6 +1440,12 @@ ZSTDLIB_API size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx, const void* pre
  */
 ZSTDLIB_API size_t ZSTD_DCtx_setMaxWindowSize(ZSTD_DCtx* dctx, size_t maxWindowSize);
 
+/* ZSTD_d_format
+ * experimental parameter,
+ * allowing selection between ZSTD_format_e input compression formats
+ */
+#define ZSTD_d_format ZSTD_d_experimentalParam1
+
 /*! ZSTD_DCtx_setFormat() :
  *  Instruct the decoder context about what kind of data to decode next.
  *  This instruction is mandatory to decode data without a fully-formed header,