Alluseri / Riza

Lua string.pack/unpack implementation in C#, made primarily to assist the creation of private servers for Unity games with XLua backends.

Riza

Lua string.pack/unpack implementation in C#, made primarily to assist the creation of private servers for Unity games with XLua backends.

Only x64 systems. I have no respect towards nuint.

Please use MessagePack instead of Riza, unless you are using it purposefully(e.g. for XLua private servers). This project's intention and purpose is clear.

Major differences between string.pack and LuaPack

• LuaPack.Pack does not care if the format option is signed or not, while Lua will raise an Integer Overflow error if the value indeed overflows:

print(string.pack(">b", 254)); -- input:1: bad argument #2 to 'pack' (integer overflow)

• LuaPack does not and will most likely never support the ! and X options.
• LuaPack does not support j, J, n and z options yet.
• LuaPack allows you to use byte counts higher than 16 in i/I/s/c[n] options, unlike Lua.
• All overloads of LuaPack.Unpack will NOT fail if the data feed ends prematurely.

Usage

Use LuaPack.Pack & LuaPack.PackBytes just like you would use string.pack in Lua. For this piece of code:

print(string.pack(">I4B<iLs", 1, 2, 3, 4, "abc"));

The direct LuaPack representation would be:

Console.WriteLine(LuaPack.PackToString(">I4B<iLs", 1, 2, 3, 4, "abc"));

And this is how to use LuaPack.Unpack & LuaPack.UnpackUnboxed. Those are really the only ways. You're not the only one disappointed.

Warning: The 'i' and 'I' options will ALWAYS be written into the type ulong when boxed, so don't forget to cast to that first.

uint Field1;
byte Field2;
int Field3;
ulong Field4;
string Field5;

List<object> Unpack1 = LuaPack.Unpack(">I4B<iLs", VarPacked); // Supports the entire set
Field1 = (uint) (ulong) Unpack1[0];
Field2 = (byte) Unpack1[1];
Field3 = (int) (ulong) Unpack1[2];
Field4 = (ulong) Unpack1[3];
Field5 = (string) Unpack1[4];

List<ulong> Unpack2 = LuaPack.UnpackUnboxed(">I4B<iL", VarPacked); // Faster, doesn't support s and c, f and d are rounded down(unrecoverable)
Field1 = (uint) Unpack2[0];
Field2 = (byte) Unpack2[1];
Field3 = (int) Unpack2[2];
Field4 = (ulong) Unpack2[3];
// Field5 is not set because s is not supported

Performance Benchmarks

Tested on a Ryzen 7 5800X w/ 32 GB RAM on Arch Linux(linux kernel).

Unpack vs UnpackUnboxed

Keep in mind that UnpackUnboxed doesn't support s, c, f and d, and therefore those are not used here.

• class SmallDummy: >L<lI4>i3>BI - 6 fields: ulong, long, (uint) ulong, (int) ulong, byte, (uint) ulong
• class LargeDummy: >L<lI4>i3>BI<L>lI4<i3<BI - 12 fields: ulong, long, (uint) ulong, (int) ulong, byte, (uint) ulong, ulong, long, (uint) ulong, (int) ulong, byte, (uint) ulong

Method	Mean	Error	StdDev
UnpackSmall	150.8 ns	2.83 ns	2.50 ns
UnpackSmallUnboxed	104.3 ns	1.97 ns	1.94 ns
UnpackLarge	276.9 ns	3.88 ns	3.63 ns
UnpackLargeUnboxed	191.7 ns	1.54 ns	1.28 ns

Big Endian

Big Endian is fully supported when packing and unpacking, thus using the > flag is fully supported and will work; but options i/I/s/c[n] will not work correctly under a Big Endian memory layout (e.g. under Solaris).

The name