only measure a variable integer once where we can (#500)

2 files changed, 19 insertions, 7 deletions

diff --git a/src/zencore/compactbinary.cpp b/src/zencore/compactbinary.cpp
index 5b599dda3..416b49f62 100644
--- a/src/zencore/compactbinary.cpp
+++ b/src/zencore/compactbinary.cpp
@@ -1319,7 +1319,7 @@ TryMeasureCompactBinary(MemoryView View, CbFieldType& OutType, uint64_t& OutSize
 			return false;
 		}
 
-		const uint64_t NameLen	= ReadVarUInt(View.GetData(), NameLenByteCount);
+		const uint64_t NameLen	= ReadMeasuredVarUInt(View.GetData(), NameLenByteCount);
 		const uint64_t NameSize = NameLen + NameLenByteCount;
 
 		if (bDynamicSize && View.GetSize() < NameSize)
@@ -1353,7 +1353,7 @@ TryMeasureCompactBinary(MemoryView View, CbFieldType& OutType, uint64_t& OutSize
 					OutSize = Size + PayloadSizeByteCount;
 					return false;
 				}
-				const uint64_t PayloadSize = ReadVarUInt(View.GetData(), PayloadSizeByteCount);
+				const uint64_t PayloadSize = ReadMeasuredVarUInt(View.GetData(), PayloadSizeByteCount);
 				OutSize					   = Size + PayloadSize + PayloadSizeByteCount;
 			}
 			return true;
diff --git a/src/zencore/include/zencore/varint.h b/src/zencore/include/zencore/varint.h
index e57e1d497..c0d63d814 100644
--- a/src/zencore/include/zencore/varint.h
+++ b/src/zencore/include/zencore/varint.h
@@ -104,15 +104,12 @@ MeasureVarInt(int64_t InValue)
  * Read a variable-length unsigned integer.
  *
  * @param InData A variable-length encoding of an unsigned integer.
- * @param OutByteCount The number of bytes consumed from the input.
+ * @param ByteCount The number of bytes to be consumed from the input.
  * @return An unsigned integer.
  */
 inline uint64_t
-ReadVarUInt(const void* InData, uint32_t& OutByteCount)
+ReadMeasuredVarUInt(const void* InData, uint32_t ByteCount)
 {
-	const uint32_t ByteCount = MeasureVarUInt(InData);
-	OutByteCount			 = ByteCount;
-
 	const uint8_t* InBytes = static_cast<const uint8_t*>(InData);
 	uint64_t	   Value   = *InBytes++ & uint8_t(0xff >> ByteCount);
 	switch (ByteCount - 1)
@@ -155,6 +152,21 @@ ReadVarUInt(const void* InData, uint32_t& OutByteCount)
 }
 
 /**
+ * Read a variable-length unsigned integer.
+ *
+ * @param InData A variable-length encoding of an unsigned integer.
+ * @param OutByteCount The number of bytes consumed from the input.
+ * @return An unsigned integer.
+ */
+inline uint64_t
+ReadVarUInt(const void* InData, uint32_t& OutByteCount)
+{
+	const uint32_t ByteCount = MeasureVarUInt(InData);
+	OutByteCount			 = ByteCount;
+	return ReadMeasuredVarUInt(InData, ByteCount);
+}
+
+/**
  * Read a variable-length signed integer.
  *
  * @param InData A variable-length encoding of a signed integer.