Streamline the decodeFlags() routine in btree.c for a small performance

increase.

FossilOrigin-Name: 4cb285210b4a2b14c80962bf2ecb35be310d3444c329c15d86b3073096455704

1 files changed, 45 insertions, 40 deletions

diff --git a/src/btree.c b/src/btree.c
index 1c6c14d4b..569b596c5 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -1900,62 +1900,67 @@ static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
 ** Only the following combinations are supported.  Anything different
 ** indicates a corrupt database files:
 **
-**         PTF_ZERODATA
-**         PTF_ZERODATA | PTF_LEAF
-**         PTF_LEAFDATA | PTF_INTKEY
-**         PTF_LEAFDATA | PTF_INTKEY | PTF_LEAF
+**         PTF_ZERODATA                             (0x02,  2)
+**         PTF_LEAFDATA | PTF_INTKEY                (0x05,  5)
+**         PTF_ZERODATA | PTF_LEAF                  (0x0a, 10)
+**         PTF_LEAFDATA | PTF_INTKEY | PTF_LEAF     (0x0d, 13)
 */
 static int decodeFlags(MemPage *pPage, int flagByte){
   BtShared *pBt;     /* A copy of pPage->pBt */
 
   assert( pPage->hdrOffset==(pPage->pgno==1 ? 100 : 0) );
   assert( sqlite3_mutex_held(pPage->pBt->mutex) );
-  pPage->leaf = (u8)(flagByte>>3);  assert( PTF_LEAF == 1<<3 );
-  flagByte &= ~PTF_LEAF;
-  pPage->childPtrSize = 4-4*pPage->leaf;
   pBt = pPage->pBt;
-  if( flagByte==(PTF_LEAFDATA | PTF_INTKEY) ){
-    /* EVIDENCE-OF: R-07291-35328 A value of 5 (0x05) means the page is an
-    ** interior table b-tree page. */
-    assert( (PTF_LEAFDATA|PTF_INTKEY)==5 );
-    /* EVIDENCE-OF: R-26900-09176 A value of 13 (0x0d) means the page is a
-    ** leaf table b-tree page. */
-    assert( (PTF_LEAFDATA|PTF_INTKEY|PTF_LEAF)==13 );
-    pPage->intKey = 1;
-    if( pPage->leaf ){
+  pPage->max1bytePayload = pBt->max1bytePayload;
+  if( flagByte>=(PTF_ZERODATA | PTF_LEAF) ){
+    pPage->childPtrSize = 0;
+    pPage->leaf = 1;
+    if( flagByte==(PTF_LEAFDATA | PTF_INTKEY | PTF_LEAF) ){
       pPage->intKeyLeaf = 1;
       pPage->xCellSize = cellSizePtrTableLeaf;
       pPage->xParseCell = btreeParseCellPtr;
+      pPage->intKey = 1;
+      pPage->maxLocal = pBt->maxLeaf;
+      pPage->minLocal = pBt->minLeaf;
+    }else if( flagByte==(PTF_ZERODATA | PTF_LEAF) ){
+      pPage->intKey = 0;
+      pPage->intKeyLeaf = 0;
+      pPage->xCellSize = cellSizePtr;
+      pPage->xParseCell = btreeParseCellPtrIndex;
+      pPage->maxLocal = pBt->maxLocal;
+      pPage->minLocal = pBt->minLocal;
     }else{
+      pPage->intKey = 0;
+      pPage->intKeyLeaf = 0;
+      pPage->xCellSize = cellSizePtr;
+      pPage->xParseCell = btreeParseCellPtrIndex;
+      return SQLITE_CORRUPT_PAGE(pPage);
+    }
+  }else{
+    pPage->childPtrSize = 4;
+    pPage->leaf = 0;
+    if( flagByte==(PTF_ZERODATA) ){
+      pPage->intKey = 0;
+      pPage->intKeyLeaf = 0;
+      pPage->xCellSize = cellSizePtr;
+      pPage->xParseCell = btreeParseCellPtrIndex;
+      pPage->maxLocal = pBt->maxLocal;
+      pPage->minLocal = pBt->minLocal;
+    }else if( flagByte==(PTF_LEAFDATA | PTF_INTKEY) ){
       pPage->intKeyLeaf = 0;
       pPage->xCellSize = cellSizePtrNoPayload;
       pPage->xParseCell = btreeParseCellPtrNoPayload;
+      pPage->intKey = 1;
+      pPage->maxLocal = pBt->maxLeaf;
+      pPage->minLocal = pBt->minLeaf;
+    }else{
+      pPage->intKey = 0;
+      pPage->intKeyLeaf = 0;
+      pPage->xCellSize = cellSizePtr;
+      pPage->xParseCell = btreeParseCellPtrIndex;
+      return SQLITE_CORRUPT_PAGE(pPage);
     }
-    pPage->maxLocal = pBt->maxLeaf;
-    pPage->minLocal = pBt->minLeaf;
-  }else if( flagByte==PTF_ZERODATA ){
-    /* EVIDENCE-OF: R-43316-37308 A value of 2 (0x02) means the page is an
-    ** interior index b-tree page. */
-    assert( (PTF_ZERODATA)==2 );
-    /* EVIDENCE-OF: R-59615-42828 A value of 10 (0x0a) means the page is a
-    ** leaf index b-tree page. */
-    assert( (PTF_ZERODATA|PTF_LEAF)==10 );
-    pPage->intKey = 0;
-    pPage->intKeyLeaf = 0;
-    pPage->xCellSize = cellSizePtr;
-    pPage->xParseCell = btreeParseCellPtrIndex;
-    pPage->maxLocal = pBt->maxLocal;
-    pPage->minLocal = pBt->minLocal;
-  }else{
-    /* EVIDENCE-OF: R-47608-56469 Any other value for the b-tree page type is
-    ** an error. */
-    pPage->intKey = 0;
-    pPage->intKeyLeaf = 0;
-    pPage->xCellSize = cellSizePtr;
-    pPage->xParseCell = btreeParseCellPtrIndex;
-    return SQLITE_CORRUPT_PAGE(pPage);
   }
-  pPage->max1bytePayload = pBt->max1bytePayload;
   return SQLITE_OK;
 }