Add bitfield decoder

protocol-derive/Cargo.toml

@@ -16,3 +16,7 @@ proc-macro = true
 proc-macro2 = "1.0"
 syn = "1.0"
 quote = "1.0"
+
+[dev-dependencies]
+minecraft-protocol = { version = "0.1.0", path = "../protocol" }
+byteorder = "1"

protocol-derive/src/lib.rs

@@ -5,7 +5,7 @@ use proc_macro2::TokenStream as TokenStream2;
 use proc_macro2::{Ident, Span};
 use quote::{quote, TokenStreamExt};
 use std::iter::FromIterator;
-use syn::{parse_macro_input, Data, DeriveInput, Field, Fields, Lit, Meta, NestedMeta};
+use syn::{parse_macro_input, Data, DeriveInput, Field, Fields, Lit, Meta, NestedMeta, Type};
 
 #[proc_macro_derive(Packet, attributes(packet))]
 pub fn derive_packet(input: proc_macro::TokenStream) -> TokenStream1 {
@@ -19,6 +19,8 @@ pub fn derive_packet(input: proc_macro::TokenStream) -> TokenStream1 {
             let encoder = impl_encoder_trait(name, fields);
             let decoder = impl_decoder_trait(name, fields);
 
+            println!("{}", decoder);
+
             TokenStream1::from(quote! {
                 #encoder
 
@@ -64,6 +66,10 @@ fn impl_encoder_trait(name: &Ident, fields: &Fields) -> TokenStream2 {
 }
 
 fn impl_decoder_trait(name: &Ident, fields: &Fields) -> TokenStream2 {
+    let mut bitfields = vec![];
+    let total_fields = fields.iter().count();
+    let mut current = 0;
+
     let decode = quote_field(fields, |field| {
         let name = &field.ident;
         let ty = &field.ty;
@@ -71,27 +77,57 @@ fn impl_decoder_trait(name: &Ident, fields: &Fields) -> TokenStream2 {
         let unparsed_meta = get_packet_field_meta(field);
         let parsed_meta = parse_packet_field_meta(&unparsed_meta);
 
-        // This is special case because max length are used only for strings.
+        let mut result = quote!();
-        if let Some(max_length) = parsed_meta.max_length {
+
-            return quote! {
+        // When we encounter a bitfield, we skip writing until we get
-                let #name = crate::DecoderReadExt::read_string(reader, #max_length)?;
+        // to the last bit field or the last field.
+        match &parsed_meta.bitfield {
+            Some(bitfield) => {
+                bitfields.push((field.clone(), bitfield.clone()));
+            }
+            None => {
+                result.append_all(quote_decoder_bitfield(&bitfields));
+                bitfields.clear();
+            }
+        }
+
+        current += 1;
+
+        if !bitfields.is_empty() {
+            return if current == total_fields {
+                result.append_all(quote_decoder_bitfield(&bitfields));
+                bitfields.clear();
+                result
+            } else {
+                quote!()
             };
         }
 
-        match parsed_meta.module {
+        // This is special case because max length are used only for strings.
-            Some(module) => {
+        if let Some(max_length) = parsed_meta.max_length {
-                let module_ident = Ident::new(&module, Span::call_site());
+            result.append_all(quote! {
+                let #name = crate::DecoderReadExt::read_string(reader, #max_length)?;
+            });
 
-                quote! {
+            return result;
+        }
+
+        match &parsed_meta.module {
+            Some(module) => {
+                let module_ident = Ident::new(module, Span::call_site());
+
+                result.append_all(quote! {
                     let #name = crate::#module_ident::decode(reader)?;
-                }
+                })
             }
             None => {
-                quote! {
+                result.append_all(quote! {
                     let #name = <#ty as crate::Decoder>::decode(reader)?;
-                }
+                });
             }
         }
+
+        return result;
     });
 
     let create = quote_field(fields, |field| {
@@ -122,11 +158,148 @@ fn impl_decoder_trait(name: &Ident, fields: &Fields) -> TokenStream2 {
 struct PacketFieldMeta {
     module: Option<String>,
     max_length: Option<u16>,
+    bitfield: Option<Bitfield>,
+}
+
+#[derive(Debug, Clone)]
+struct Bitfield {
+    size: usize,
+}
+
+macro_rules! decode_bitmask_value (
+    ($value: expr, $name: ident) => (
+        fn $name(
+            result: &mut TokenStream2,
+            name: &Option<Ident>,
+            ty: &Type,
+            bitfield_size: usize,
+            current: usize,
+            signed: bool,
+        ) {
+            let mask = (2 << (bitfield_size - 1)) - $value;
+            let bool = match ty {
+                Type::Path(type_path) => type_path
+                    .path
+                    .get_ident()
+                    .expect("Failed to get ident")
+                    .to_string() == "bool",
+                _ => false,
+            };
+
+            if bool {
+              if current > 0 {
+                result.append_all(quote! {
+                  let mut #name = ((encoded >> #current) & #mask) != 0;
+                });
+              } else {
+                result.append_all(quote! {
+                  let mut #name = (encoded & #mask) != 0;
+                });
+              }
+            } else {
+              if current > 0 {
+                result.append_all(quote! {
+                  let mut #name = ((encoded >> #current) & #mask) as #ty;
+                });
+              } else {
+                result.append_all(quote! {
+                  let mut #name = (encoded & #mask) as #ty;
+                });
+              }
+            }
+
+            if signed {
+              let subtract = mask + 1;
+              let overflow = subtract >> 1;
+
+              result.append_all(quote! {
+                  if #name > #overflow as #ty {
+                    #name -= #subtract as #ty;
+                  }
+              });
+            }
+        }
+    )
+);
+
+decode_bitmask_value!(1i64, decode_i64_bitmask_value);
+decode_bitmask_value!(1i32, decode_i32_bitmask_value);
+decode_bitmask_value!(1i16, decode_i16_bitmask_value);
+decode_bitmask_value!(1i8, decode_i8_bitmask_value);
+
+fn quote_decoder_bitfield(bitfields: &Vec<(Field, Bitfield)>) -> TokenStream2 {
+    if bitfields.is_empty() {
+        return quote!();
+    }
+
+    let total_size: usize = bitfields.iter().map(|(_, b)| b.size).sum();
+
+    let mut result = read_decoder_bitfield_quote(total_size);
+    let mut current = total_size;
+
+    for (field, bitfield) in bitfields {
+        current -= bitfield.size;
+
+        let name = &field.ident;
+        let ty = &field.ty;
+
+        let signed = match ty {
+            Type::Path(type_path) => type_path
+                .path
+                .get_ident()
+                .expect("Failed to get ident")
+                .to_string()
+                .starts_with("i"),
+            _ => panic!("Unexpected bitfield type"),
+        };
+
+        match total_size {
+            _ if total_size == 64 => {
+                decode_i64_bitmask_value(&mut result, name, ty, bitfield.size, current, signed)
+            }
+            _ if total_size == 32 => {
+                decode_i32_bitmask_value(&mut result, name, ty, bitfield.size, current, signed)
+            }
+            _ if total_size == 16 => {
+                decode_i16_bitmask_value(&mut result, name, ty, bitfield.size, current, signed)
+            }
+            _ => decode_i8_bitmask_value(&mut result, name, ty, bitfield.size, current, signed),
+        }
+    }
+
+    return result;
+}
+
+fn read_decoder_bitfield_quote(total_size: usize) -> TokenStream2 {
+    match total_size {
+        _ if total_size == 64 => {
+            quote! {
+                let encoded = ::byteorder::ReadBytesExt::read_i64::<::byteorder::BigEndian>(reader)?;
+            }
+        }
+        _ if total_size == 32 => {
+            quote! {
+                let encoded = ::byteorder::ReadBytesExt::read_i32::<::byteorder::BigEndian>(reader)?;
+            }
+        }
+        _ if total_size == 16 => {
+            quote! {
+                let encoded = ::byteorder::ReadBytesExt::read_i16::<::byteorder::BigEndian>(reader)?;
+            }
+        }
+        _ if total_size == 8 => {
+            quote! {
+                let encoded = ::byteorder::ReadBytesExt::read_i8(reader)?;
+            }
+        }
+        _ => panic!("Bitfield size must be aligned to 8, 16, 32 or 64"),
+    }
 }
 
 fn parse_packet_field_meta(meta_list: &Vec<NestedMeta>) -> PacketFieldMeta {
     let mut module = None;
     let mut max_length = None;
+    let mut bitfield = None;
 
     for meta in meta_list {
         match meta {
@@ -147,14 +320,46 @@ fn parse_packet_field_meta(meta_list: &Vec<NestedMeta>) -> PacketFieldMeta {
                 },
                 path => panic!(
                     "Received unrecognized attribute : \"{}\"",
-                    path.get_ident().unwrap()
+                    path.get_ident().expect("Failed to get ident")
                 ),
             },
-            _ => panic!("Expected only named meta values"),
+            NestedMeta::Meta(Meta::List(meta_list)) if meta_list.path.is_ident("bitfield") => {
+                let mut size = None;
+
+                for meta in &meta_list.nested {
+                    match meta {
+                        NestedMeta::Meta(Meta::NameValue(named_meta)) => match &named_meta.path {
+                            path if path.is_ident("size") => match &named_meta.lit {
+                                Lit::Int(lit_int) => {
+                                    size = Some(
+                                        lit_int
+                                            .base10_parse::<usize>()
+                                            .expect("Failed to parse size attribute"),
+                                    )
+                                }
+                                _ => panic!("\"size\" attribute value must be integer"),
+                            },
+                            path => panic!(
+                                "Received unrecognized attribute : \"{}\"",
+                                path.get_ident().expect("Failed to get ident")
+                            ),
+                        },
+                        _ => panic!("Unexpected field meta"),
+                    }
+                }
+
+                let size = size.unwrap_or_else(|| panic!("Size must be specified in bitfield"));
+                bitfield = Some(Bitfield { size })
+            }
+            _ => panic!("Unexpected field meta"),
         }
     }
 
-    PacketFieldMeta { module, max_length }
+    PacketFieldMeta {
+        module,
+        max_length,
+        bitfield,
+    }
 }
 
 fn get_packet_field_meta(field: &Field) -> Vec<NestedMeta> {
@@ -171,7 +376,7 @@ fn get_packet_field_meta(field: &Field) -> Vec<NestedMeta> {
         .collect()
 }
 
-fn quote_field<F: Fn(&Field) -> TokenStream2>(fields: &Fields, func: F) -> TokenStream2 {
+fn quote_field<F: FnMut(&Field) -> TokenStream2>(fields: &Fields, mut func: F) -> TokenStream2 {
     let mut output = quote!();
 
     match fields {

protocol-derive/tests/bitfield_abilities.rs

@@ -0,0 +1,60 @@
+#[macro_use]
+extern crate minecraft_protocol_derive;
+
+use minecraft_protocol::decoder::Decoder;
+use minecraft_protocol::encoder::Encoder;
+use minecraft_protocol::error::{DecodeError, EncodeError};
+
+#[derive(Packet)]
+pub struct Abilities {
+    #[packet(bitfield(size = 4))]
+    pub _unused: u8,
+    #[packet(bitfield(size = 1))]
+    pub creative_mode: bool,
+    #[packet(bitfield(size = 1))]
+    pub allow_flying: bool,
+    #[packet(bitfield(size = 1))]
+    pub flying: bool,
+    #[packet(bitfield(size = 1))]
+    pub invulnerable: bool,
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::Abilities;
+    use minecraft_protocol::decoder::Decoder;
+    use minecraft_protocol::encoder::Encoder;
+    use minecraft_protocol::error::{DecodeError, EncodeError};
+    use std::io::Cursor;
+
+    #[test]
+    fn test_encode_abilities_i8_bitfield() {
+        let abilities = Abilities {
+            _unused: 0,
+            creative_mode: true,
+            allow_flying: true,
+            flying: true,
+            invulnerable: true,
+        };
+        let mut vec = Vec::new();
+
+        abilities
+            .encode(&mut vec)
+            .expect("Failed to encode abilities");
+        assert_eq!(vec, [15]);
+    }
+
+    #[test]
+    fn test_decode_abilities_i8_bitfield() {
+        let value = 15i8;
+
+        let vec = value.to_be_bytes().to_vec();
+        let mut cursor = Cursor::new(vec);
+
+        let abilities = Abilities::decode(&mut cursor).expect("Failed to decode abilities");
+        assert!(abilities.invulnerable);
+        assert!(abilities.flying);
+        assert!(abilities.allow_flying);
+        assert!(abilities.creative_mode);
+    }
+}

protocol-derive/tests/bitfield_half.rs

@@ -0,0 +1,107 @@
+#[macro_use]
+extern crate minecraft_protocol_derive;
+
+use minecraft_protocol::decoder::Decoder;
+use minecraft_protocol::encoder::Encoder;
+use minecraft_protocol::error::{DecodeError, EncodeError};
+
+#[derive(Packet)]
+pub struct HalfLong {
+    #[packet(bitfield(size = 32))]
+    pub _unused: u32,
+    #[packet(bitfield(size = 32))]
+    pub value: u32,
+}
+
+#[derive(Packet)]
+pub struct HalfInt {
+    #[packet(bitfield(size = 16))]
+    pub _unused: u16,
+    #[packet(bitfield(size = 16))]
+    pub value: u16,
+}
+
+#[derive(Packet)]
+pub struct HalfShort {
+    #[packet(bitfield(size = 8))]
+    pub _unused: u8,
+    #[packet(bitfield(size = 8))]
+    pub value: u8,
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{HalfInt, HalfLong, HalfShort};
+    use minecraft_protocol::decoder::Decoder;
+    use minecraft_protocol::encoder::Encoder;
+    use minecraft_protocol::error::{DecodeError, EncodeError};
+    use std::io::Cursor;
+
+    #[test]
+    fn test_encode_half_long_u64_bitfield() {
+        let half = HalfLong {
+            _unused: 0,
+            value: u32::MAX,
+        };
+        let mut vec = Vec::new();
+
+        half.encode(&mut vec).expect("Failed to encode half");
+        assert_eq!(vec, u32::MAX.to_be_bytes().to_vec());
+    }
+
+    #[test]
+    fn test_decode_half_long_u64_bitfield() {
+        let value = u32::MAX as u64;
+
+        let vec = value.to_be_bytes().to_vec();
+        let mut cursor = Cursor::new(vec);
+
+        let half = HalfLong::decode(&mut cursor).expect("Failed to decode half");
+        assert_eq!(half.value, u32::MAX);
+    }
+
+    #[test]
+    fn test_encode_half_int_u32_bitfield() {
+        let half = HalfInt {
+            _unused: 0,
+            value: u16::MAX,
+        };
+        let mut vec = Vec::new();
+
+        half.encode(&mut vec).expect("Failed to encode half");
+        assert_eq!(vec, u16::MAX.to_be_bytes().to_vec());
+    }
+
+    #[test]
+    fn test_decode_half_int_u32_bitfield() {
+        let value = u16::MAX as u32;
+
+        let vec = value.to_be_bytes().to_vec();
+        let mut cursor = Cursor::new(vec);
+
+        let half = HalfInt::decode(&mut cursor).expect("Failed to decode half");
+        assert_eq!(half.value, u16::MAX);
+    }
+
+    #[test]
+    fn test_encode_half_short_u8_bitfield() {
+        let half = HalfShort {
+            _unused: 0,
+            value: u8::MAX,
+        };
+        let mut vec = Vec::new();
+
+        half.encode(&mut vec).expect("Failed to encode half");
+        assert_eq!(vec, u8::MAX.to_be_bytes().to_vec());
+    }
+
+    #[test]
+    fn test_decode_half_short_u8_bitfield() {
+        let value = u8::MAX as u16;
+        let vec = value.to_be_bytes().to_vec();
+        let mut cursor = Cursor::new(vec);
+
+        let half = HalfShort::decode(&mut cursor).expect("Failed to decode half");
+        assert_eq!(half.value, u8::MAX);
+    }
+}

protocol-derive/tests/bitfield_position.rs

@@ -0,0 +1,54 @@
+#[macro_use]
+extern crate minecraft_protocol_derive;
+
+use minecraft_protocol::decoder::Decoder;
+use minecraft_protocol::encoder::Encoder;
+use minecraft_protocol::error::{DecodeError, EncodeError};
+
+#[derive(Packet)]
+pub struct Position {
+    #[packet(bitfield(size = 26))]
+    pub x: i32,
+    #[packet(bitfield(size = 26))]
+    pub z: i32,
+    #[packet(bitfield(size = 12))]
+    pub y: u16,
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::Position;
+    use minecraft_protocol::decoder::Decoder;
+    use minecraft_protocol::encoder::Encoder;
+    use minecraft_protocol::error::{DecodeError, EncodeError};
+    use std::io::Cursor;
+
+    #[test]
+    fn test_encode_position_i64_bitfield() {
+        let position = Position {
+            x: 1000,
+            y: 64,
+            z: -1000,
+        };
+
+        let mut vec = Vec::new();
+
+        position
+            .encode(&mut vec)
+            .expect("Failed to encode position");
+
+        assert_eq!(vec, 275152780755008i64.to_be_bytes().to_vec());
+    }
+
+    #[test]
+    fn test_decode_position_i64_bitfield() {
+        let value = -137164079660992i64;
+        let vec = value.to_be_bytes().to_vec();
+        let mut cursor = Cursor::new(vec);
+        let position = Position::decode(&mut cursor).expect("Failed to decode position");
+
+        assert_eq!(position.x, -500);
+        assert_eq!(position.y, 64);
+        assert_eq!(position.z, -1000);
+    }
+}

protocol/src/decoder.rs

@@ -5,7 +5,7 @@ use num_traits::FromPrimitive;
 use std::io::Read;
 use uuid::Uuid;
 
-trait Decoder {
+pub trait Decoder {
     type Output;
 
     fn decode<R: Read>(reader: &mut R) -> Result<Self::Output, DecodeError>;
@@ -109,6 +109,14 @@ impl Decoder for u8 {
     }
 }
 
+impl Decoder for i16 {
+    type Output = Self;
+
+    fn decode<R: Read>(reader: &mut R) -> Result<Self::Output, DecodeError> {
+        Ok(reader.read_i16::<BigEndian>()?)
+    }
+}
+
 impl Decoder for i32 {
     type Output = Self;
 
@@ -117,6 +125,14 @@ impl Decoder for i32 {
     }
 }
 
+impl Decoder for u16 {
+    type Output = Self;
+
+    fn decode<R: Read>(reader: &mut R) -> Result<Self::Output, DecodeError> {
+        Ok(reader.read_u16::<BigEndian>()?)
+    }
+}
+
 impl Decoder for u32 {
     type Output = Self;
 

protocol/src/encoder.rs

@@ -5,7 +5,7 @@ use num_traits::ToPrimitive;
 use std::io::Write;
 use uuid::Uuid;
 
-trait Encoder {
+pub trait Encoder {
     fn encode<W: Write>(&self, writer: &mut W) -> Result<(), EncodeError>;
 }
 
@@ -103,12 +103,24 @@ impl Encoder for u8 {
     }
 }
 
+impl Encoder for i16 {
+    fn encode<W: Write>(&self, writer: &mut W) -> Result<(), EncodeError> {
+        Ok(writer.write_i16::<BigEndian>(*self)?)
+    }
+}
+
 impl Encoder for i32 {
     fn encode<W: Write>(&self, writer: &mut W) -> Result<(), EncodeError> {
         Ok(writer.write_i32::<BigEndian>(*self)?)
     }
 }
 
+impl Encoder for u16 {
+    fn encode<W: Write>(&self, writer: &mut W) -> Result<(), EncodeError> {
+        Ok(writer.write_u16::<BigEndian>(*self)?)
+    }
+}
+
 impl Encoder for u32 {
     fn encode<W: Write>(&self, writer: &mut W) -> Result<(), EncodeError> {
         Ok(writer.write_u32::<BigEndian>(*self)?)