removed ZSTD_decompressBegin() from ZSTD_initDCtx_internal()

It does not feel "right" from a dependency perspective.
ZSTD_initDCtx_internal() is triggered once, on DCtx creation,
while ZSTD_decompressBegin() is invoked at the beginning of each new frame,
and is also a user-facing prototype.

Downside : a DCtx must be init before first usage !
This was always the intention by the way, and is documented as such.
This stage is automatically done within ZSTD_decompress() and variants,
and also within ZSTD_decompressStream().
Only ZSTD_decompressContinue() is impacted,
it must be preceded by a ZSTD_decompressBegin(), as detailed in doc.

A test has been fixed, to no longer rely on undocumented assumption that ZSTD_decompressBegin() is invoked during init.

diff --git a/lib/decompress/zstd_decompress.c b/lib/decompress/zstd_decompress.c
index 332bf860d2bd646b5095db41cda743f13691a6ee..960d9332f762542769660ec1b3b16334235c1bb3 100644 (file)
--- a/lib/decompress/zstd_decompress.c
+++ b/lib/decompress/zstd_decompress.c
@@ -162,33 +162,9 @@ static size_t ZSTD_startingInputLength(ZSTD_format_e format)
     return startingInputLength;
 }
 
-/* Note : this function cannot fail */
-size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx)
-{
-    assert(dctx != NULL);
-    dctx->expected = ZSTD_startingInputLength(dctx->format);
-    dctx->stage = ZSTDds_getFrameHeaderSize;
-    dctx->decodedSize = 0;
-    dctx->previousDstEnd = NULL;
-    dctx->base = NULL;
-    dctx->vBase = NULL;
-    dctx->dictEnd = NULL;
-    dctx->entropy.hufTable[0] = (HUF_DTable)((HufLog)*0x1000001);  /* cover both little and big endian */
-    dctx->litEntropy = dctx->fseEntropy = 0;
-    dctx->dictID = 0;
-    ZSTD_STATIC_ASSERT(sizeof(dctx->entropy.rep) == sizeof(repStartValue));
-    memcpy(dctx->entropy.rep, repStartValue, sizeof(repStartValue));  /* initial repcodes */
-    dctx->LLTptr = dctx->entropy.LLTable;
-    dctx->MLTptr = dctx->entropy.MLTable;
-    dctx->OFTptr = dctx->entropy.OFTable;
-    dctx->HUFptr = dctx->entropy.hufTable;
-    return 0;
-}
-
 static void ZSTD_initDCtx_internal(ZSTD_DCtx* dctx)
 {
     dctx->format = ZSTD_f_zstd1;  /* ZSTD_decompressBegin() invokes ZSTD_startingInputLength() with argument dctx->format */
-    ZSTD_decompressBegin(dctx);   /* cannot fail */
     dctx->staticSize  = 0;
     dctx->maxWindowSize = ZSTD_MAXWINDOWSIZE_DEFAULT;
     dctx->ddict       = NULL;
@@ -542,7 +518,8 @@ static size_t ZSTD_setRleBlock(void* dst, size_t dstCapacity,
 }
 
 /*! ZSTD_decodeLiteralsBlock() :
- * @return : nb of bytes read from src (< srcSize ) */
+ * @return : nb of bytes read from src (< srcSize )
+ *  note : symbol not declared but exposed for fullbench */
 size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
                           const void* src, size_t srcSize)   /* note : srcSize < BLOCKSIZE */
 {
@@ -2003,6 +1980,29 @@ static size_t ZSTD_decompress_insertDictionary(ZSTD_DCtx* dctx, const void* dict
     return ZSTD_refDictContent(dctx, dict, dictSize);
 }
 
+/* Note : this function cannot fail */
+size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx)
+{
+    assert(dctx != NULL);
+    dctx->expected = ZSTD_startingInputLength(dctx->format);  /* dctx->format must be properly set */
+    dctx->stage = ZSTDds_getFrameHeaderSize;
+    dctx->decodedSize = 0;
+    dctx->previousDstEnd = NULL;
+    dctx->base = NULL;
+    dctx->vBase = NULL;
+    dctx->dictEnd = NULL;
+    dctx->entropy.hufTable[0] = (HUF_DTable)((HufLog)*0x1000001);  /* cover both little and big endian */
+    dctx->litEntropy = dctx->fseEntropy = 0;
+    dctx->dictID = 0;
+    ZSTD_STATIC_ASSERT(sizeof(dctx->entropy.rep) == sizeof(repStartValue));
+    memcpy(dctx->entropy.rep, repStartValue, sizeof(repStartValue));  /* initial repcodes */
+    dctx->LLTptr = dctx->entropy.LLTable;
+    dctx->MLTptr = dctx->entropy.MLTable;
+    dctx->OFTptr = dctx->entropy.OFTable;
+    dctx->HUFptr = dctx->entropy.hufTable;
+    return 0;
+}
+
 size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize)
 {
     CHECK_F( ZSTD_decompressBegin(dctx) );

diff --git a/tests/fullbench.c b/tests/fullbench.c
index bd9dc6135e731ef6a93429661466efe7fa8a34dc..db00ce217b0e06aa836f03096a7b48630f752697 100644 (file)
--- a/tests/fullbench.c
+++ b/tests/fullbench.c
@@ -376,6 +376,7 @@ static size_t benchMem(const void* src, size_t srcSize, U32 benchNb)
             skippedSize = frameHeaderSize + ZSTD_blockHeaderSize;
             memcpy(buff2, dstBuff+skippedSize, g_cSize-skippedSize);
             srcSize = srcSize > 128 KB ? 128 KB : srcSize;    /* speed relative to block */
+            ZSTD_decompressBegin(g_zdc);
             break;
         }
     case 32:   /* ZSTD_decodeSeqHeaders */