Add ioBase::i64_dyn_v2

soup/Reader.cpp

@@ -73,4 +73,21 @@ NAMESPACE_SOUP
 
 		return true;
 	}
+
+	bool Reader::i64_dyn_v2(int64_t& v) noexcept
+	{
+		uint64_t u;
+		SOUP_RETHROW_FALSE(u64_dyn_v2(u));
+		const bool neg = (u >> 6) & 1; // check bit 6
+		u = ((u >> 1) & ~0x3f) | (u & 0x3f); // remove bit 6
+		if (neg)
+		{
+			v = (u * -1) - 1;
+		}
+		else
+		{
+			v = u;
+		}
+		return true;
+	}
 }

soup/Reader.hpp

@@ -41,6 +41,9 @@ NAMESPACE_SOUP
 		// An unsigned 64-bit integer encoded in 1..9 bytes. This is a slightly more efficient version of u64_dyn, e.g. 0x4000..0x407f are encoded in 2 bytes instead of 3.
 		bool u64_dyn_v2(uint64_t& v) noexcept;
 
+		// A signed 64-bit integer encoded in 1..9 bytes. (Specialisation of u64_dyn_v2. This revision also simplifies how negative integers are handled.)
+		bool i64_dyn_v2(int64_t& v) noexcept;
+
 		// An integer where every byte's most significant bit is used to indicate if another byte follows, most significant byte first.
 		template <typename Int>
 		bool om(Int& v) noexcept

soup/Writer.cpp

@@ -73,6 +73,21 @@ NAMESPACE_SOUP
 		return ret;
 	}
 
+	bool Writer::i64_dyn_v2(const int64_t& v) noexcept
+	{
+		uint64_t u;
+		bool neg = (v < 0);
+		if (neg)
+		{
+			u = (v * -1) - 1;
+		}
+		else
+		{
+			u = v;
+		}
+		return u64_dyn_v2(((uint64_t)neg << 6) | ((u & ~0x3f) << 1) | (u & 0x3f));
+	}
+
 	bool Writer::mysql_lenenc(const uint64_t& v) noexcept
 	{
 		if (v < 0xFB)

soup/Writer.hpp

@@ -31,6 +31,9 @@ NAMESPACE_SOUP
 		// An unsigned 64-bit integer encoded in 1..9 bytes. This is a slightly more efficient version of u64_dyn, e.g. 0x4000..0x407f are encoded in 2 bytes instead of 3.
 		bool u64_dyn_v2(const uint64_t& v) noexcept;
 
+		// A signed 64-bit integer encoded in 1..9 bytes. (Specialisation of u64_dyn_v2. This revision also simplifies how negative integers are handled.)
+		bool i64_dyn_v2(const int64_t& v) noexcept;
+
 		// An integer where every byte's most significant bit is used to indicate if another byte follows, most significant byte first.
 		template <typename Int>
 		bool om(const Int& v) noexcept