Merge branch 'master' of github.com:gavofyork/ethcore-util

benches/rlp.rs

@@ -0,0 +1,95 @@
+//! benchmarking for rlp
+//! should be started with:
+//! ```bash
+//! multirust run nightly cargo bench 
+//! ```
+
+#![feature(test)]
+
+extern crate test;
+extern crate ethcore_util;
+
+use test::Bencher;
+use std::str::FromStr;
+use ethcore_util::rlp::{RlpStream, Rlp, Decodable};
+use ethcore_util::uint::U256;
+
+#[bench]
+fn bench_stream_u64_value(b: &mut Bencher) {
+    b.iter( || {
+        //1029
+        let mut stream = RlpStream::new();
+        stream.append(&0x1023456789abcdefu64);
+        let _ = stream.out().unwrap();
+    });
+}
+
+#[bench]
+fn bench_decode_u64_value(b: &mut Bencher) {
+    b.iter( || {
+        // 1029
+        let data = vec![0x88, 0x10, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef]; 
+        let rlp = Rlp::new(&data);
+        let _ = u64::decode(&rlp).unwrap();
+    });
+}
+
+#[bench]
+fn bench_stream_u256_value(b: &mut Bencher) {
+    b.iter( || {
+        //u256
+        let mut stream = RlpStream::new();
+        stream.append(&U256::from_str("8090a0b0c0d0e0f00910203040506077000000000000000100000000000012f0").unwrap());
+        let _ = stream.out().unwrap();
+    });
+}
+
+#[bench]
+fn bench_decode_u256_value(b: &mut Bencher) {
+    b.iter( || {
+        // u256
+        let data = vec![0xa0, 0x80, 0x90, 0xa0, 0xb0, 0xc0, 0xd0, 0xe0, 0xf0,
+                       0x09, 0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x77,
+                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
+                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x12, 0xf0];
+        let rlp = Rlp::new(&data);
+        let _ = U256::decode(&rlp).unwrap();
+    });
+}
+
+#[bench]
+fn bench_stream_nested_empty_lists(b: &mut Bencher) {
+    b.iter( || {
+        // [ [], [[]], [ [], [[]] ] ]
+        let mut stream = RlpStream::new_list(3);
+        stream.append_list(0);
+        stream.append_list(1).append_list(0);
+        stream.append_list(2).append_list(0).append_list(1).append_list(0);
+        let _ = stream.out().unwrap();
+    });
+}
+
+#[bench]
+fn bench_decode_nested_empty_lists(b: &mut Bencher) {
+    b.iter( || {
+        // [ [], [[]], [ [], [[]] ] ]
+        let data = vec![0xc7, 0xc0, 0xc1, 0xc0, 0xc3, 0xc0, 0xc1, 0xc0];
+        let rlp = Rlp::new(&data);
+        let _v0: Vec<u8> = Decodable::decode(&rlp.at(0).unwrap()).unwrap();
+        let _v1: Vec<Vec<u8>> = Decodable::decode(&rlp.at(1).unwrap()).unwrap();
+        let nested_rlp = rlp.at(2).unwrap();
+        let _v2a: Vec<u8> = Decodable::decode(&nested_rlp.at(0).unwrap()).unwrap();
+        let _v2b: Vec<Vec<u8>> = Decodable::decode(&nested_rlp.at(1).unwrap()).unwrap();
+    });
+}
+
+#[bench]
+fn bench_stream_1000_empty_lists(b: &mut Bencher) {
+    b.iter( || {
+        let mut stream = RlpStream::new_list(1000);
+        for _ in 0..1000 {
+            stream.append_list(0);
+        }
+        let _ = stream.out().unwrap();
+    });
+}

src/bytes.rs

@@ -8,6 +8,7 @@
 
 use std::fmt;
 use std::error::Error as StdError;
+use uint::{U128, U256};
 
 /// TODO: optimise some conversations
 pub trait ToBytes {
@@ -59,6 +60,7 @@ impl ToBytes for u64 {
     fn to_bytes(&self) -> Vec<u8> {
         let mut res= vec![];
         let count = self.to_bytes_len();
+        res.reserve(count);
         for i in 0..count {
             let j = count - 1 - i;
             res.push((*self >> (j * 8)) as u8);
@@ -82,6 +84,27 @@ impl_map_to_bytes!(usize, u64);
 impl_map_to_bytes!(u16, u64);
 impl_map_to_bytes!(u32, u64);
 
+macro_rules! impl_uint_to_bytes {
+    ($name: ident) => {
+        impl ToBytes for $name {
+            fn to_bytes(&self) -> Vec<u8> { 
+                let mut res= vec![];
+                let count = self.to_bytes_len();
+                res.reserve(count);
+                for i in 0..count {
+                    let j = count - 1 - i;
+                    res.push(self.byte(j));
+                }
+                res
+            }
+            fn to_bytes_len(&self) -> usize { (self.bits() + 7) / 8 }
+        }
+    }
+}
+
+impl_uint_to_bytes!(U256);
+impl_uint_to_bytes!(U128);
+
 #[derive(Debug, PartialEq, Eq)]
 pub enum FromBytesError {
     UnexpectedEnd
@@ -101,6 +124,7 @@ pub type FromBytesResult<T> = Result<T, FromBytesError>;
 
 /// implements "Sized", so the compiler can deducate the size
 /// of the return type
+/// TODO: check size of bytes before conversation and return appropriate error
 pub trait FromBytes: Sized {
     fn from_bytes(bytes: &[u8]) -> FromBytesResult<Self>;
 }
@@ -149,3 +173,16 @@ macro_rules! impl_map_from_bytes {
 impl_map_from_bytes!(usize, u64);
 impl_map_from_bytes!(u16, u64);
 impl_map_from_bytes!(u32, u64);
+
+macro_rules! impl_uint_from_bytes {
+    ($name: ident) => {
+        impl FromBytes for $name {
+            fn from_bytes(bytes: &[u8]) -> FromBytesResult<$name> {
+                Ok($name::from(bytes))
+            }
+        }
+    }
+}
+
+impl_uint_from_bytes!(U256);
+impl_uint_from_bytes!(U128);

src/lib.rs

@@ -4,8 +4,10 @@ pub use std::str::FromStr;
 
 pub mod error;
 pub mod hash;
+pub mod uint;
 pub mod bytes;
 pub mod rlp;
+pub mod vector;
 
 #[test]
 fn it_works() {

src/rlp.rs

@@ -1,9 +1,54 @@
 //! Rlp serialization module
+//!
+//! Types implementing `Endocable` and `Decodable` traits
+//! can be easily coverted to and from rlp
+//! 
+//! # Examples:
+//! 
+//! ```rust
+//! extern crate ethcore_util;
+//! use ethcore_util::rlp::{RlpStream};
+//! 
+//! fn encode_value() {
+//!     // 1029
+//!     let mut stream = RlpStream::new();
+//!     stream.append(&1029u32);
+//!     let out = stream.out().unwrap();
+//!     assert_eq!(out, vec![0x82, 0x04, 0x05]);
+//! }
+//!
+//! fn encode_list() {
+//!     // [ "cat", "dog" ]
+//!     let mut stream = RlpStream::new_list(2);
+//!     stream.append(&"cat").append(&"dog");
+//!     let out = stream.out().unwrap();
+//!     assert_eq!(out, vec![0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o', b'g']);
+//! }
+//! 
+//! fn encode_list2() {
+//!     // [ [], [[]], [ [], [[]] ] ]
+//!     let mut stream = RlpStream::new_list(3);
+//!     stream.append_list(0);
+//!     stream.append_list(1).append_list(0);
+//!     stream.append_list(2).append_list(0).append_list(1).append_list(0);
+//!     let out = stream.out().unwrap();
+//!     assert_eq!(out, vec![0xc7, 0xc0, 0xc1, 0xc0, 0xc3, 0xc0, 0xc1, 0xc0]);
+//! }
+//!
+//! fn main() {
+//!     encode_value();
+//!     encode_list();
+//!     encode_list2();
+//! }
+//! ```
+//!
 
 use std::fmt;
 use std::cell::Cell;
+use std::collections::LinkedList;
 use std::error::Error as StdError;
-use bytes::{FromBytes, FromBytesError};
+use bytes::{ToBytes, FromBytes, FromBytesError};
+use vector::InsertSlice;
 
 /// rlp container
 #[derive(Debug)]
@@ -41,7 +86,8 @@ impl ItemInfo {
 pub enum DecoderError {
     FromBytesError(FromBytesError),
     RlpIsTooShort,
-    RlpExpectedToBeArray,
+    RlpExpectedToBeList,
+    RlpExpectedToBeValue,
     BadRlp,
 }
 impl StdError for DecoderError {
@@ -71,16 +117,16 @@ impl <'a>Rlp<'a> {
     ///
     /// paren container caches searched position
     pub fn at(&self, index: usize) -> Result<Rlp<'a>, DecoderError> {
-        if !self.is_array() {
-            return Err(DecoderError::RlpExpectedToBeArray);
+        if !self.is_list() {
+            return Err(DecoderError::RlpExpectedToBeList);
         }
 
         // move to cached position if it's index is less or equal to
-        // current search index, otherwise move to beginning of array
+        // current search index, otherwise move to beginning of list
         let c = self.cache.get();
         let (mut bytes, to_skip) = match c.index <= index {
             true => (try!(Rlp::consume(self.bytes, c.offset)), index - c.index),
-            false => (try!(self.consume_array_prefix()), index)
+            false => (try!(self.consume_list_prefix()), index)
         };
 
         // skip up to x items
@@ -94,8 +140,8 @@ impl <'a>Rlp<'a> {
         Ok(Rlp::new(&bytes[0..found.prefix_len + found.value_len]))
     }
 
-    /// returns true if rlp is an array
-    pub fn is_array(&self) -> bool {
+    /// returns true if rlp is a list
+    pub fn is_list(&self) -> bool {
         self.bytes.len() > 0 && self.bytes[0] >= 0xc0
     }
 
@@ -110,7 +156,7 @@ impl <'a>Rlp<'a> {
     }
 
     /// consumes first found prefix
-    fn consume_array_prefix(&self) -> Result<&'a [u8], DecoderError> {
+    fn consume_list_prefix(&self) -> Result<&'a [u8], DecoderError> {
         let item = try!(Rlp::item_info(self.bytes));
         let bytes = try!(Rlp::consume(self.bytes, item.prefix_len));
         Ok(bytes)
@@ -189,29 +235,315 @@ impl <'a> Iterator for RlpIterator<'a> {
     }
 }
 
+/// shortcut function to decode a Rlp `&[u8]` into an object
+pub fn decode<T>(bytes: &[u8]) -> Result<T, DecoderError> where T: Decodable {
+    let rlp = Rlp::new(bytes);
+    T::decode(&rlp)
+}
+
+pub trait Decodable: Sized {
+    fn decode(rlp: &Rlp) -> Result<Self, DecoderError>;
+}
+
+impl <T> Decodable for T where T: FromBytes {
+    fn decode(rlp: &Rlp) -> Result<Self, DecoderError> {
+        match rlp.is_value() {
+            true => BasicDecoder::read_value(rlp.bytes),
+            false => Err(DecoderError::RlpExpectedToBeValue)
+        }
+    }
+}
+
+impl <T> Decodable for Vec<T> where T: Decodable {
+    fn decode(rlp: &Rlp) -> Result<Self, DecoderError> {
+        match rlp.is_list() {
+            true => rlp.iter().map(|rlp| T::decode(&rlp)).collect(),
+            false => Err(DecoderError::RlpExpectedToBeList)
+        }
+    }
+}
+
+pub trait Decoder {
+    fn read_value<T>(bytes: &[u8]) -> Result<T, DecoderError> where T: FromBytes;
+}
+
+struct BasicDecoder;
+
+impl Decoder for BasicDecoder {
+    fn read_value<T>(bytes: &[u8]) -> Result<T, DecoderError> where T: FromBytes {
+        match bytes.first().map(|&x| x) {
+            // rlp is too short
+            None => Err(DecoderError::RlpIsTooShort),
+            // single byt value
+            Some(l @ 0...0x7f) => Ok(try!(T::from_bytes(&[l]))),
+            // 0-55 bytes
+            Some(l @ 0x80...0xb7) => Ok(try!(T::from_bytes(&bytes[1..(1 + l as usize - 0x80)]))),
+            // longer than 55 bytes
+            Some(l @ 0xb8...0xbf) => {
+                let len_of_len = l as usize - 0xb7;
+                let begin_of_value = 1 as usize + len_of_len;
+                let len = try!(usize::from_bytes(&bytes[1..begin_of_value]));
+                Ok(try!(T::from_bytes(&bytes[begin_of_value..begin_of_value + len])))
+            },
+            _ => Err(DecoderError::BadRlp)
+        }
+    }
+}
+
+#[derive(Debug)]
+struct ListInfo {
+    position: usize,
+    current: usize,
+    max: usize
+}
+
+impl ListInfo {
+    fn new(position: usize, max: usize) -> ListInfo {
+        ListInfo { 
+            position: position,
+            current: 0,
+            max: max
+        }
+    }
+}
+
+/// container that should be used to encode rlp
+pub struct RlpStream {
+    unfinished_lists: LinkedList<ListInfo>,
+    encoder: BasicEncoder
+}
+
+impl RlpStream {
+    /// create new container for values appended one after another,
+    /// but not being part of the same list
+    pub fn new() -> RlpStream {
+        RlpStream {
+            unfinished_lists: LinkedList::new(),
+            encoder: BasicEncoder::new()
+        }
+    }
+
+    /// create new container for list of size `max_len`
+    pub fn new_list(len: usize) -> RlpStream {
+        let mut stream = RlpStream::new();
+        stream.append_list(len);
+        stream
+    }
+
+    /// apends value to the end of stream, chainable
+    pub fn append<'a, E>(&'a mut self, object: &E) -> &'a mut RlpStream where E: Encodable {
+        // encode given value and add it at the end of the stream
+        object.encode(&mut self.encoder);
+
+        // if list is finished, prepend the length
+        self.try_to_finish();
+
+        // return chainable self
+        self
+    }
+
+    /// declare appending the list of given size
+    pub fn append_list<'a>(&'a mut self, len: usize) -> &'a mut RlpStream {
+        // push new list
+        let position = self.encoder.bytes.len();
+        match len {
+            0 => {
+                // we may finish, if the appended list len is equal 0
+                self.encoder.bytes.push(0xc0u8);
+                self.try_to_finish();
+            },
+            _ => self.unfinished_lists.push_back(ListInfo::new(position, len))
+        }
+
+        // return chainable self
+        self
+    }
+
+    /// return true if stream is ready
+    pub fn is_finished(&self) -> bool {
+        self.unfinished_lists.back().is_none()
+    }
+
+    /// streams out encoded bytes
+    pub fn out(self) -> Result<Vec<u8>, EncoderError> {
+        match self.is_finished() {
+            true => Ok(self.encoder.out()),
+            false => Err(EncoderError::StreamIsUnfinished)
+        }
+    }
+
+    /// try to finish lists
+    fn try_to_finish(&mut self) -> () {
+        let should_finish = match self.unfinished_lists.back_mut() {
+            None => false,
+            Some(ref mut x) => {
+                x.current += 1;
+                x.current == x.max
+            }
+        };
+
+        if should_finish {    
+            let x = self.unfinished_lists.pop_back().unwrap();
+            let len = self.encoder.bytes.len() - x.position;
+            self.encoder.insert_list_len_at_pos(len, x.position);
+            self.try_to_finish();
+        }
+    }
+}
+
+/// shortcut function to encode a `T: Encodable` into a Rlp `Vec<u8>`
+pub fn encode<E>(object: &E) -> Vec<u8> where E: Encodable {
+    let mut encoder = BasicEncoder::new();
+    object.encode(&mut encoder);
+    encoder.out()
+}
+
+#[derive(Debug)]
+pub enum EncoderError {
+    StreamIsUnfinished
+}
+
+impl StdError for EncoderError {
+    fn description(&self) -> &str { "encoder error" }
+}
+
+impl fmt::Display for EncoderError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Debug::fmt(&self, f)
+    }
+}
+
+pub trait Encodable {
+    fn encode<E>(&self, encoder: &mut E) -> () where E: Encoder;
+}
+
+pub trait Encoder {
+    fn emit_value(&mut self, bytes: &[u8]) -> ();
+    fn emit_list<F>(&mut self, f: F) -> () where F: FnOnce(&mut Self) -> ();
+}
+
+impl <T> Encodable for T where T: ToBytes {
+    fn encode<E>(&self, encoder: &mut E) -> () where E: Encoder {
+        encoder.emit_value(&self.to_bytes())
+    }
+}
+
+impl <'a, T> Encodable for &'a [T] where T: Encodable + 'a {
+    fn encode<E>(&self, encoder: &mut E) -> () where E: Encoder {
+        encoder.emit_list(|e| {
+            // insert all list elements
+            for el in self.iter() {
+                el.encode(e);
+            }
+        })
+    }
+}
+
+impl <T> Encodable for Vec<T> where T: Encodable {
+    fn encode<E>(&self, encoder: &mut E) -> () where E: Encoder {
+        let r: &[T] = self.as_ref();
+        r.encode(encoder)
+    }
+}
+
+struct BasicEncoder {
+    bytes: Vec<u8>
+}
+
+impl BasicEncoder {
+    fn new() -> BasicEncoder {
+        BasicEncoder { bytes: vec![] }
+    }
+
+    /// inserts list prefix at given position
+    /// TODO: optimise it further?
+    fn insert_list_len_at_pos(&mut self, len: usize, pos: usize) -> () {
+        let mut res = vec![];
+        match len {
+            0...55 => res.push(0xc0u8 + len as u8),
+            _ => {
+                res.push(0x7fu8 + len.to_bytes_len() as u8);
+                res.extend(len.to_bytes());
+            }
+        };
+
+        self.bytes.insert_slice(pos, &res);
+    }
+
+    /// get encoded value
+    fn out(self) -> Vec<u8> {
+        self.bytes
+    }
+}
+
+impl Encoder for BasicEncoder {
+    fn emit_value(&mut self, bytes: &[u8]) -> () {
+        match bytes.len() {
+            // just 0
+            0 => self.bytes.push(0x80u8),
+            // byte is its own encoding
+            1 if bytes[0] < 0x80 => self.bytes.extend(bytes),
+            // (prefix + length), followed by the string
+            len @ 1 ... 55 => {
+                self.bytes.push(0x80u8 + len as u8);
+                self.bytes.extend(bytes);
+            }
+            // (prefix + length of length), followed by the length, followd by the string
+            len => {
+                self.bytes.push(0xb7 + len.to_bytes_len() as u8);
+                self.bytes.extend(len.to_bytes());
+                self.bytes.extend(bytes);
+            }
+        }
+    }
+
+    fn emit_list<F>(&mut self, f: F) -> () where F: FnOnce(&mut Self) -> () {
+        // get len before inserting a list
+        let before_len = self.bytes.len();
+
+        // insert all list elements
+        f(self);
+
+        // get len after inserting a list
+        let after_len = self.bytes.len();
+
+        // diff is list len
+        let list_len = after_len - before_len;
+        self.insert_list_len_at_pos(list_len, before_len);
+    }
+}
+
 #[cfg(test)]
 mod tests {
+    use std::{fmt, cmp};
+    use std::str::FromStr;
     use rlp;
-    use rlp::Rlp;
+    use rlp::{Rlp, RlpStream, Decodable};
+    use uint::U256;
 
     #[test]
     fn rlp_at() {
         let data = vec![0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o', b'g'];
         {
             let rlp = Rlp::new(&data);
-            assert!(rlp.is_array());
+            assert!(rlp.is_list());
+            let animals = <Vec<String> as rlp::Decodable>::decode(&rlp).unwrap();
+            assert_eq!(animals, vec!["cat".to_string(), "dog".to_string()]);
            
             let cat = rlp.at(0).unwrap();
             assert!(cat.is_value());
             assert_eq!(cat.bytes, &[0x83, b'c', b'a', b't']);
+            assert_eq!(String::decode(&cat).unwrap(), "cat".to_string());
             
             let dog = rlp.at(1).unwrap();
             assert!(dog.is_value());
             assert_eq!(dog.bytes, &[0x83, b'd', b'o', b'g']);
+            assert_eq!(String::decode(&dog).unwrap(), "dog".to_string());
 
             let cat_again = rlp.at(0).unwrap();
             assert!(cat_again.is_value());
             assert_eq!(cat_again.bytes, &[0x83, b'c', b'a', b't']);
+            assert_eq!(String::decode(&cat_again).unwrap(), "cat".to_string());
         }
     }
 
@@ -220,7 +552,7 @@ mod tests {
         let data = vec![0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o'];
         {
             let rlp = Rlp::new(&data);
-            assert!(rlp.is_array());
+            assert!(rlp.is_list());
 
             let cat_err = rlp.at(0).unwrap_err();
             assert_eq!(cat_err, rlp::DecoderError::RlpIsTooShort);
@@ -253,5 +585,269 @@ mod tests {
             assert_eq!(cat_again.bytes, &[0x83, b'c', b'a', b't']);
         }
     }
+
+    struct ETestPair<T>(T, Vec<u8>) where T: rlp::Encodable;
+
+    fn run_encode_tests<T>(tests: Vec<ETestPair<T>>) where T: rlp::Encodable {
+        for t in &tests {
+            let res = rlp::encode(&t.0);
+            assert_eq!(res, &t.1[..]);
+        }
+    }
+
+    #[test]
+    fn encode_u8() {
+        let tests = vec![
+            ETestPair(0u8, vec![0x80u8]),
+            ETestPair(15, vec![15]),
+            ETestPair(55, vec![55]),
+            ETestPair(56, vec![56]),
+            ETestPair(0x7f, vec![0x7f]),
+            ETestPair(0x80, vec![0x81, 0x80]),
+            ETestPair(0xff, vec![0x81, 0xff]),
+        ];
+        run_encode_tests(tests);
+    }
+
+    #[test]
+    fn encode_u16() {
+        let tests = vec![
+            ETestPair(0u16, vec![0x80u8]),
+            ETestPair(0x100, vec![0x82, 0x01, 0x00]),
+            ETestPair(0xffff, vec![0x82, 0xff, 0xff]),
+        ];
+        run_encode_tests(tests);
+    }
+
+    #[test]
+    fn encode_u32() {
+        let tests = vec![
+            ETestPair(0u32, vec![0x80u8]),
+            ETestPair(0x10000, vec![0x83, 0x01, 0x00, 0x00]),
+            ETestPair(0xffffff, vec![0x83, 0xff, 0xff, 0xff]),
+        ];
+        run_encode_tests(tests);
+    }
+
+    #[test]
+    fn encode_u64() {
+        let tests = vec![
+            ETestPair(0u64, vec![0x80u8]),
+            ETestPair(0x1000000, vec![0x84, 0x01, 0x00, 0x00, 0x00]),
+            ETestPair(0xFFFFFFFF, vec![0x84, 0xff, 0xff, 0xff, 0xff]),
+        ];
+        run_encode_tests(tests);
+    }
+
+    #[test]
+    fn encode_u256() {
+        let tests = vec![
+            ETestPair(U256::from(0u64), vec![0x80u8]),
+            ETestPair(U256::from(0x1000000u64), vec![0x84, 0x01, 0x00, 0x00, 0x00]),
+            ETestPair(U256::from(0xffffffffu64), vec![0x84, 0xff, 0xff, 0xff, 0xff]),
+            ETestPair(U256::from_str("8090a0b0c0d0e0f00910203040506077000000000000000100000000000012f0").unwrap(),
+            vec![0xa0, 0x80, 0x90, 0xa0, 0xb0, 0xc0, 0xd0, 0xe0, 0xf0,
+                       0x09, 0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x77,
+                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
+                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x12, 0xf0])
+        ];
+        run_encode_tests(tests);
+    }
+
+    #[test]
+    fn encode_str() {
+        let tests = vec![
+            ETestPair("cat", vec![0x83, b'c', b'a', b't']),
+            ETestPair("dog", vec![0x83, b'd', b'o', b'g']),
+            ETestPair("Marek", vec![0x85, b'M', b'a', b'r', b'e', b'k']),
+            ETestPair("", vec![0x80]),
+            ETestPair("Lorem ipsum dolor sit amet, consectetur adipisicing elit",
+                     vec![0xb8, 0x38, b'L', b'o', b'r', b'e', b'm', b' ', b'i',
+                    b'p', b's', b'u', b'm', b' ', b'd', b'o', b'l', b'o', b'r',
+                    b' ', b's', b'i', b't', b' ', b'a', b'm', b'e', b't', b',',
+                    b' ', b'c', b'o', b'n', b's', b'e', b'c', b't', b'e', b't',
+                    b'u', b'r', b' ', b'a', b'd', b'i', b'p', b'i', b's', b'i',
+                    b'c', b'i', b'n', b'g', b' ', b'e', b'l', b'i', b't'])
+        ];
+        run_encode_tests(tests);
+    }
+
+    #[test]
+    fn encode_vector_u8() {
+        let tests = vec![
+            ETestPair(vec![], vec![0xc0]),
+            ETestPair(vec![15u8], vec![0xc1, 0x0f]),
+            ETestPair(vec![1, 2, 3, 7, 0xff], vec![0xc6, 1, 2, 3, 7, 0x81, 0xff]),
+        ];
+        run_encode_tests(tests);
+    }
+
+    #[test]
+    fn encode_vector_u64() {
+        let tests = vec![
+            ETestPair(vec![], vec![0xc0]),
+            ETestPair(vec![15u64], vec![0xc1, 0x0f]),
+            ETestPair(vec![1, 2, 3, 7, 0xff], vec![0xc6, 1, 2, 3, 7, 0x81, 0xff]),
+            ETestPair(vec![0xffffffff, 1, 2, 3, 7, 0xff], vec![0xcb, 0x84, 0xff, 0xff, 0xff, 0xff,  1, 2, 3, 7, 0x81, 0xff]),
+        ];
+        run_encode_tests(tests);
+    }
+
+    #[test]
+    fn encode_vector_str() {
+        let tests = vec![
+            ETestPair(vec!["cat", "dog"], vec![0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o', b'g'])
+        ];
+        run_encode_tests(tests);
+    }
+
+    #[test]
+    fn encode_vector_of_vectors_str() {
+        let tests = vec![
+            ETestPair(vec![vec!["cat"]], vec![0xc5, 0xc4, 0x83, b'c', b'a', b't'])
+        ];
+        run_encode_tests(tests);
+    }
+
+    #[test]
+    fn rlp_stream() {
+        let mut stream = RlpStream::new_list(2);
+        stream.append(&"cat").append(&"dog");
+        let out = stream.out().unwrap();
+        assert_eq!(out, vec![0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o', b'g']);
+    }
+
+    #[test]
+    fn rlp_stream_list() {
+        let mut stream = RlpStream::new_list(3);
+        stream.append_list(0);
+        stream.append_list(1).append_list(0);
+        stream.append_list(2).append_list(0).append_list(1).append_list(0);
+        let out = stream.out().unwrap();
+        assert_eq!(out, vec![0xc7, 0xc0, 0xc1, 0xc0, 0xc3, 0xc0, 0xc1, 0xc0]);
+    }
+
+    struct DTestPair<T>(T, Vec<u8>) where T: rlp::Decodable + fmt::Debug + cmp::Eq;
+
+    fn run_decode_tests<T>(tests: Vec<DTestPair<T>>) where T: rlp::Decodable + fmt::Debug  + cmp::Eq {
+        for t in &tests {
+            let res: T = rlp::decode(&t.1).unwrap();
+            assert_eq!(res, t.0);
+        }
+    }
+
+    #[test]
+    fn decode_u8() {
+        let tests = vec![
+            DTestPair(0u8, vec![0u8]),
+            DTestPair(15, vec![15]),
+            DTestPair(55, vec![55]),
+            DTestPair(56, vec![56]),
+            DTestPair(0x7f, vec![0x7f]),
+            DTestPair(0x80, vec![0x81, 0x80]),
+            DTestPair(0xff, vec![0x81, 0xff]),
+        ];
+        run_decode_tests(tests);
+    }
+
+    #[test]
+    fn decode_u16() {
+        let tests = vec![
+            DTestPair(0u16, vec![0u8]),
+            DTestPair(0x100, vec![0x82, 0x01, 0x00]),
+            DTestPair(0xffff, vec![0x82, 0xff, 0xff]),
+        ];
+        run_decode_tests(tests);
+    }
+
+    #[test]
+    fn decode_u32() {
+        let tests = vec![
+            DTestPair(0u32, vec![0u8]),
+            DTestPair(0x10000, vec![0x83, 0x01, 0x00, 0x00]),
+            DTestPair(0xffffff, vec![0x83, 0xff, 0xff, 0xff]),
+        ];
+        run_decode_tests(tests);
+    }
+
+    #[test]
+    fn decode_u64() {
+        let tests = vec![
+            DTestPair(0u64, vec![0u8]),
+            DTestPair(0x1000000, vec![0x84, 0x01, 0x00, 0x00, 0x00]),
+            DTestPair(0xFFFFFFFF, vec![0x84, 0xff, 0xff, 0xff, 0xff]),
+        ];
+        run_decode_tests(tests);
+    }
+
+    #[test]
+    fn decode_u256() {
+        let tests = vec![
+            DTestPair(U256::from(0u64), vec![0x80u8]),
+            DTestPair(U256::from(0x1000000u64), vec![0x84, 0x01, 0x00, 0x00, 0x00]),
+            DTestPair(U256::from(0xffffffffu64), vec![0x84, 0xff, 0xff, 0xff, 0xff]),
+            DTestPair(U256::from_str("8090a0b0c0d0e0f00910203040506077000000000000000100000000000012f0").unwrap(),
+            vec![0xa0, 0x80, 0x90, 0xa0, 0xb0, 0xc0, 0xd0, 0xe0, 0xf0,
+                       0x09, 0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x77,
+                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
+                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x12, 0xf0])
+        ];
+        run_decode_tests(tests);
+    }
+
+    #[test]
+    fn decode_str() {
+        let tests = vec![
+            DTestPair("cat".to_string(), vec![0x83, b'c', b'a', b't']),
+            DTestPair("dog".to_string(), vec![0x83, b'd', b'o', b'g']),
+            DTestPair("Marek".to_string(), vec![0x85, b'M', b'a', b'r', b'e', b'k']),
+            DTestPair("".to_string(), vec![0x80]),
+            DTestPair("Lorem ipsum dolor sit amet, consectetur adipisicing elit".to_string(),
+                     vec![0xb8, 0x38, b'L', b'o', b'r', b'e', b'm', b' ', b'i',
+                    b'p', b's', b'u', b'm', b' ', b'd', b'o', b'l', b'o', b'r',
+                    b' ', b's', b'i', b't', b' ', b'a', b'm', b'e', b't', b',',
+                    b' ', b'c', b'o', b'n', b's', b'e', b'c', b't', b'e', b't',
+                    b'u', b'r', b' ', b'a', b'd', b'i', b'p', b'i', b's', b'i',
+                    b'c', b'i', b'n', b'g', b' ', b'e', b'l', b'i', b't'])
+        ];
+        run_decode_tests(tests);
+    }
+    
+    #[test]
+    fn decode_vector_u8() {
+        let tests = vec![
+            DTestPair(vec![] as Vec<u8>, vec![0xc0]),
+            DTestPair(vec![15u8], vec![0xc1, 0x0f]),
+            DTestPair(vec![1u8, 2, 3, 7, 0xff], vec![0xc6, 1, 2, 3, 7, 0x81, 0xff]),
+        ];
+        run_decode_tests(tests);
+    }
+
+    #[test]
+    fn decode_vector_u64() {
+        let tests = vec![
+            DTestPair(vec![], vec![0xc0]),
+            DTestPair(vec![15u64], vec![0xc1, 0x0f]),
+            DTestPair(vec![1, 2, 3, 7, 0xff], vec![0xc6, 1, 2, 3, 7, 0x81, 0xff]),
+            DTestPair(vec![0xffffffff, 1, 2, 3, 7, 0xff], vec![0xcb, 0x84, 0xff, 0xff, 0xff, 0xff,  1, 2, 3, 7, 0x81, 0xff]),
+        ];
+        run_decode_tests(tests);
+    }
+
+    #[test]
+    fn decode_vector_str() {
+        let tests = vec![
+            DTestPair(vec!["cat".to_string(), "dog".to_string()], vec![0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o', b'g'])
+        ];
+        run_decode_tests(tests);
+    }
+
+    #[test]
+    fn decode_vector_of_vectors_str() {
+        let tests = vec![
+            DTestPair(vec![vec!["cat".to_string()]], vec![0xc5, 0xc4, 0x83, b'c', b'a', b't'])
+        ];
+        run_decode_tests(tests);
+    }
 }
 

src/uint.rs

@@ -0,0 +1,610 @@
+// taken from Rust Bitcoin Library (https://github.com/apoelstra/rust-bitcoin)
+// original author: Andrew Poelstra <apoelstra@wpsoftware.net>
+
+// Rust Bitcoin Library
+// Written in 2014 by
+//     Andrew Poelstra <apoelstra@wpsoftware.net>
+//
+// To the extent possible under law, the author(s) have dedicated all
+// copyright and related and neighboring rights to this software to
+// the public domain worldwide. This software is distributed without
+// any warranty.
+//
+// You should have received a copy of the CC0 Public Domain Dedication
+// along with this software.
+// If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
+//
+
+//! Big unsigned integer types
+///!
+///! Implementation of a various large-but-fixed sized unsigned integer types.
+///! The functions here are designed to be fast.
+///!
+
+use std::fmt;
+use std::cmp::{Ord, PartialOrd, Ordering};
+use std::ops::*;
+use std::str::FromStr;
+use rustc_serialize::hex::{FromHex, FromHexError};
+
+macro_rules! impl_map_from {
+    ($thing:ident, $from:ty, $to:ty) => {
+        impl From<$from> for $thing {
+            fn from(value: $from) -> $thing {
+                From::from(value as $to)
+            }
+        }
+    }
+}
+
+macro_rules! impl_array_newtype {
+    ($thing:ident, $ty:ty, $len:expr) => {
+        impl $thing {
+            #[inline]
+            /// Converts the object to a raw pointer
+            pub fn as_ptr(&self) -> *const $ty {
+                let &$thing(ref dat) = self;
+                dat.as_ptr()
+            }
+
+            #[inline]
+            /// Converts the object to a mutable raw pointer
+            pub fn as_mut_ptr(&mut self) -> *mut $ty {
+                let &mut $thing(ref mut dat) = self;
+                dat.as_mut_ptr()
+            }
+
+            #[inline]
+            /// Returns the length of the object as an array
+            pub fn len(&self) -> usize { $len }
+
+            #[inline]
+            /// Returns whether the object, as an array, is empty. Always false.
+            pub fn is_empty(&self) -> bool { false }
+        }
+
+        impl<'a> From<&'a [$ty]> for $thing {
+            fn from(data: &'a [$ty]) -> $thing {
+                assert_eq!(data.len(), $len);
+                unsafe {
+                    use std::intrinsics::copy_nonoverlapping;
+                    use std::mem;
+                    let mut ret: $thing = mem::uninitialized();
+                    copy_nonoverlapping(data.as_ptr(),
+                                        ret.as_mut_ptr(),
+                                        mem::size_of::<$thing>());
+                    ret
+                }
+            }
+        }
+
+        impl Index<usize> for $thing {
+            type Output = $ty;
+
+            #[inline]
+            fn index(&self, index: usize) -> &$ty {
+                let &$thing(ref dat) = self;
+                &dat[index]
+            }
+        }
+
+        impl_index_newtype!($thing, $ty);
+
+        impl PartialEq for $thing {
+            #[inline]
+            fn eq(&self, other: &$thing) -> bool {
+                &self[..] == &other[..]
+            }
+        }
+
+        impl Eq for $thing {}
+
+        impl Clone for $thing {
+            #[inline]
+            fn clone(&self) -> $thing {
+                $thing::from(&self[..])
+            }
+        }
+
+        impl Copy for $thing {}
+    }
+}
+
+macro_rules! impl_index_newtype {
+    ($thing:ident, $ty:ty) => {
+        impl Index<Range<usize>> for $thing {
+            type Output = [$ty];
+
+            #[inline]
+            fn index(&self, index: Range<usize>) -> &[$ty] {
+                &self.0[index]
+            }
+        }
+
+        impl Index<RangeTo<usize>> for $thing {
+            type Output = [$ty];
+
+            #[inline]
+            fn index(&self, index: RangeTo<usize>) -> &[$ty] {
+                &self.0[index]
+            }
+        }
+
+        impl Index<RangeFrom<usize>> for $thing {
+            type Output = [$ty];
+
+            #[inline]
+            fn index(&self, index: RangeFrom<usize>) -> &[$ty] {
+                &self.0[index]
+            }
+        }
+
+        impl Index<RangeFull> for $thing {
+            type Output = [$ty];
+
+            #[inline]
+            fn index(&self, _: RangeFull) -> &[$ty] {
+                &self.0[..]
+            }
+        }
+    }
+}
+
+macro_rules! construct_uint {
+    ($name:ident, $n_words:expr) => (
+        /// Little-endian large integer type
+        pub struct $name(pub [u64; $n_words]);
+        impl_array_newtype!($name, u64, $n_words);
+
+        impl $name {
+            /// Conversion to u32
+            #[inline]
+            fn low_u32(&self) -> u32 {
+                let &$name(ref arr) = self;
+                arr[0] as u32
+            }
+
+            /// Return the least number of bits needed to represent the number
+            #[inline]
+            pub fn bits(&self) -> usize {
+                let &$name(ref arr) = self;
+                for i in 1..$n_words {
+                    if arr[$n_words - i] > 0 { return (0x40 * ($n_words - i + 1)) - arr[$n_words - i].leading_zeros() as usize; }
+                }
+                0x40 - arr[0].leading_zeros() as usize
+            }
+
+            #[inline]
+            pub fn bit(&self, index: usize) -> bool {
+                let &$name(ref arr) = self;
+                arr[index / 64] & (1 << (index % 64)) != 0
+            }
+
+            #[inline]
+            pub fn byte(&self, index: usize) -> u8 {
+                let &$name(ref arr) = self;
+                (arr[index / 8] >> ((index % 8)) * 8) as u8
+            }
+
+            /// Multiplication by u32
+            fn mul_u32(self, other: u32) -> $name {
+                let $name(ref arr) = self;
+                let mut carry = [0u64; $n_words];
+                let mut ret = [0u64; $n_words];
+                for i in 0..$n_words {
+                    let upper = other as u64 * (arr[i] >> 32);
+                    let lower = other as u64 * (arr[i] & 0xFFFFFFFF);
+                    if i < 3 {
+                        carry[i + 1] += upper >> 32;
+                    }
+                    ret[i] = lower + (upper << 32);
+                }
+                $name(ret) + $name(carry)
+            }
+        }
+
+        impl From<u64> for $name {
+            fn from(value: u64) -> $name {
+                let mut ret = [0; $n_words];
+                ret[0] = value;
+                $name(ret)
+            }
+        }
+
+        impl_map_from!($name, u8, u64);
+        impl_map_from!($name, u16, u64);
+        impl_map_from!($name, u32, u64);
+
+        impl<'a> From<&'a [u8]> for $name {
+            fn from(bytes: &[u8]) -> $name {
+                assert!($n_words * 8 >= bytes.len());
+
+                let mut ret = [0; $n_words];
+                for i in 0..bytes.len() {
+                    let rev = bytes.len() - 1 - i;
+                    let pos = rev / 8;
+                    ret[pos] += (bytes[i] as u64) << (rev % 8) * 8;
+                }
+                $name(ret)
+            }
+        }
+
+        impl FromStr for $name {
+            type Err = FromHexError;
+
+            fn from_str(value: &str) -> Result<$name, Self::Err> {
+                let bytes: &[u8] = &try!(value.from_hex());
+                Ok(From::from(bytes))
+            }
+        }
+
+        impl Add<$name> for $name {
+            type Output = $name;
+
+            fn add(self, other: $name) -> $name {
+                let $name(ref me) = self;
+                let $name(ref you) = other;
+                let mut ret = [0u64; $n_words];
+                let mut carry = [0u64; $n_words];
+                let mut b_carry = false;
+                for i in 0..$n_words {
+                    ret[i] = me[i].wrapping_add(you[i]);
+                    if i < $n_words - 1 && ret[i] < me[i] {
+                        carry[i + 1] = 1;
+                        b_carry = true;
+                    }
+                }
+                if b_carry { $name(ret) + $name(carry) } else { $name(ret) }
+            }
+        }
+
+        impl Sub<$name> for $name {
+            type Output = $name;
+
+            #[inline]
+            fn sub(self, other: $name) -> $name {
+                self + !other + From::from(1u64)
+            }
+        }
+
+        impl Mul<$name> for $name {
+            type Output = $name;
+
+            fn mul(self, other: $name) -> $name {
+                let mut me = self;
+                // TODO: be more efficient about this
+                for i in 0..(2 * $n_words) {
+                    me = (me + me.mul_u32((other >> (32 * i)).low_u32())) << (32 * i);
+                }
+                me
+            }
+        }
+
+        impl Div<$name> for $name {
+            type Output = $name;
+
+            fn div(self, other: $name) -> $name {
+                let mut sub_copy = self;
+                let mut shift_copy = other;
+                let mut ret = [0u64; $n_words];
+        
+                let my_bits = self.bits();
+                let your_bits = other.bits();
+
+                // Check for division by 0
+                assert!(your_bits != 0);
+
+                // Early return in case we are dividing by a larger number than us
+                if my_bits < your_bits {
+                    return $name(ret);
+                }
+
+                // Bitwise long division
+                let mut shift = my_bits - your_bits;
+                shift_copy = shift_copy << shift;
+                loop {
+                    if sub_copy >= shift_copy {
+                        ret[shift / 64] |= 1 << (shift % 64);
+                        sub_copy = sub_copy - shift_copy;
+                    }
+                    shift_copy = shift_copy >> 1;
+                    if shift == 0 { break; }
+                    shift -= 1;
+                }
+
+                $name(ret)
+            }
+        }
+
+        impl BitAnd<$name> for $name {
+            type Output = $name;
+
+            #[inline]
+            fn bitand(self, other: $name) -> $name {
+                let $name(ref arr1) = self;
+                let $name(ref arr2) = other;
+                let mut ret = [0u64; $n_words];
+                for i in 0..$n_words {
+                    ret[i] = arr1[i] & arr2[i];
+                }
+                $name(ret)
+            }
+        }
+
+        impl BitXor<$name> for $name {
+            type Output = $name;
+
+            #[inline]
+            fn bitxor(self, other: $name) -> $name {
+                let $name(ref arr1) = self;
+                let $name(ref arr2) = other;
+                let mut ret = [0u64; $n_words];
+                for i in 0..$n_words {
+                    ret[i] = arr1[i] ^ arr2[i];
+                }
+                $name(ret)
+            }
+        }
+
+        impl BitOr<$name> for $name {
+            type Output = $name;
+
+            #[inline]
+            fn bitor(self, other: $name) -> $name {
+                let $name(ref arr1) = self;
+                let $name(ref arr2) = other;
+                let mut ret = [0u64; $n_words];
+                for i in 0..$n_words {
+                    ret[i] = arr1[i] | arr2[i];
+                }
+                $name(ret)
+            }
+        }
+
+        impl Not for $name {
+            type Output = $name;
+
+            #[inline]
+            fn not(self) -> $name {
+                let $name(ref arr) = self;
+                let mut ret = [0u64; $n_words];
+                for i in 0..$n_words {
+                    ret[i] = !arr[i];
+                }
+                $name(ret)
+            }
+        }
+
+        impl Shl<usize> for $name {
+            type Output = $name;
+
+            fn shl(self, shift: usize) -> $name {
+                let $name(ref original) = self;
+                let mut ret = [0u64; $n_words];
+                let word_shift = shift / 64;
+                let bit_shift = shift % 64;
+                for i in 0..$n_words {
+                    // Shift
+                    if bit_shift < 64 && i + word_shift < $n_words {
+                        ret[i + word_shift] += original[i] << bit_shift;
+                    }
+                    // Carry
+                    if bit_shift > 0 && i + word_shift + 1 < $n_words {
+                        ret[i + word_shift + 1] += original[i] >> (64 - bit_shift);
+                    }
+                }
+                $name(ret)
+            }
+        }
+
+        impl Shr<usize> for $name {
+            type Output = $name;
+
+            fn shr(self, shift: usize) -> $name {
+                let $name(ref original) = self;
+                let mut ret = [0u64; $n_words];
+                let word_shift = shift / 64;
+                let bit_shift = shift % 64;
+                for i in word_shift..$n_words {
+                    // Shift
+                    ret[i - word_shift] += original[i] >> bit_shift;
+                    // Carry
+                    if bit_shift > 0 && i < $n_words - 1 {
+                        ret[i - word_shift] += original[i + 1] << (64 - bit_shift);
+                    }
+                }
+                $name(ret)
+            }
+        }
+
+        impl Ord for $name {
+            fn cmp(&self, other: &$name) -> Ordering {
+                let &$name(ref me) = self;
+                let &$name(ref you) = other;
+                for i in 0..$n_words {
+                    if me[$n_words - 1 - i] < you[$n_words - 1 - i] { return Ordering::Less; }
+                    if me[$n_words - 1 - i] > you[$n_words - 1 - i] { return Ordering::Greater; }
+                }
+                Ordering::Equal
+            }
+        }
+
+        impl PartialOrd for $name {
+            fn partial_cmp(&self, other: &$name) -> Option<Ordering> {
+                Some(self.cmp(other))
+            }
+        }
+
+        impl fmt::Debug for $name {
+            fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+                let &$name(ref data) = self;
+                try!(write!(f, "0x"));
+                for ch in data.iter().rev() {
+                    try!(write!(f, "{:02x}", ch));
+                }
+                Ok(())
+            }
+        }
+    );
+}
+
+construct_uint!(U256, 4);
+construct_uint!(U128, 2);
+
+impl From<U128> for U256 {
+    fn from(value: U128) -> U256 {
+        let U128(ref arr) = value; 
+        let mut ret = [0; 4];
+        ret[0] = arr[0];
+        ret[1] = arr[1];
+        U256(ret)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use uint::U256;
+    use std::str::FromStr;
+
+    #[test]
+    pub fn uint256_from() {
+        let e = U256([10, 0, 0, 0]);
+
+        // test unsigned initialization
+        let ua = U256::from(10u8);
+        let ub = U256::from(10u16);
+        let uc =  U256::from(10u32);
+        let ud = U256::from(10u64);
+        assert_eq!(e, ua);
+        assert_eq!(e, ub);
+        assert_eq!(e, uc);
+        assert_eq!(e, ud);
+        
+        // test initialization from bytes
+        let va = U256::from(&[10u8][..]);
+        assert_eq!(e, va);
+
+        // more tests for initialization from bytes
+        assert_eq!(U256([0x1010, 0, 0, 0]), U256::from(&[0x10u8, 0x10][..]));
+        assert_eq!(U256([0x12f0, 0, 0, 0]), U256::from(&[0x12u8, 0xf0][..]));
+        assert_eq!(U256([0x12f0, 0, 0, 0]), U256::from(&[0, 0x12u8, 0xf0][..]));
+        assert_eq!(U256([0x12f0, 0 , 0, 0]), U256::from(&[0, 0, 0, 0, 0, 0, 0, 0x12u8, 0xf0][..]));
+        assert_eq!(U256([0x12f0, 1 , 0, 0]), U256::from(&[1, 0, 0, 0, 0, 0, 0, 0x12u8, 0xf0][..]));
+        assert_eq!(U256([0x12f0, 1 , 0x0910203040506077, 0x8090a0b0c0d0e0f0]), U256::from(&[
+                                                                                          0x80, 0x90, 0xa0, 0xb0, 0xc0, 0xd0, 0xe0, 0xf0,
+                                                                                          0x09, 0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x77,
+                                                                                          0, 0, 0, 0, 0, 0, 0, 1, 
+                                                                                          0, 0, 0, 0, 0, 0, 0x12u8, 0xf0][..]));
+        assert_eq!(U256([0x00192437100019fa, 0x243710, 0, 0]), U256::from(&[
+                                                                          0x24u8, 0x37, 0x10,
+                                                                          0, 0x19, 0x24, 0x37, 0x10, 0, 0x19, 0xfa][..]));
+
+        // test initializtion from string
+        let sa = U256::from_str("0a").unwrap();
+        assert_eq!(e, sa);
+        assert_eq!(U256([0x1010, 0, 0, 0]), U256::from_str("1010").unwrap());
+        assert_eq!(U256([0x12f0, 0, 0, 0]), U256::from_str("12f0").unwrap());
+        assert_eq!(U256([0x12f0, 0, 0, 0]), U256::from_str("12f0").unwrap());
+        assert_eq!(U256([0x12f0, 0 , 0, 0]), U256::from_str("0000000012f0").unwrap());
+        assert_eq!(U256([0x12f0, 1 , 0, 0]), U256::from_str("0100000000000012f0").unwrap());
+        assert_eq!(U256([0x12f0, 1 , 0x0910203040506077, 0x8090a0b0c0d0e0f0]), U256::from_str("8090a0b0c0d0e0f00910203040506077000000000000000100000000000012f0").unwrap());
+    }
+
+    #[test]
+    pub fn uint256_bits_test() {
+        assert_eq!(U256::from(0u64).bits(), 0);
+        assert_eq!(U256::from(255u64).bits(), 8);
+        assert_eq!(U256::from(256u64).bits(), 9);
+        assert_eq!(U256::from(300u64).bits(), 9);
+        assert_eq!(U256::from(60000u64).bits(), 16);
+        assert_eq!(U256::from(70000u64).bits(), 17);
+   
+        //// Try to read the following lines out loud quickly
+        let mut shl = U256::from(70000u64);
+        shl = shl << 100;
+        assert_eq!(shl.bits(), 117);
+        shl = shl << 100;
+        assert_eq!(shl.bits(), 217);
+        shl = shl << 100;
+        assert_eq!(shl.bits(), 0);
+
+        //// Bit set check
+        //// 01010
+        assert!(!U256::from(10u8).bit(0));
+        assert!(U256::from(10u8).bit(1));
+        assert!(!U256::from(10u8).bit(2));
+        assert!(U256::from(10u8).bit(3));
+        assert!(!U256::from(10u8).bit(4));
+
+        //// byte check
+        assert_eq!(U256::from(10u8).byte(0), 10);
+        assert_eq!(U256::from(0xffu64).byte(0), 0xff);
+        assert_eq!(U256::from(0xffu64).byte(1), 0);
+        assert_eq!(U256::from(0x01ffu64).byte(0), 0xff);
+        assert_eq!(U256::from(0x01ffu64).byte(1), 0x1);
+        assert_eq!(U256([0u64, 0xfc, 0, 0]).byte(8), 0xfc);
+        assert_eq!(U256([0u64, 0, 0, u64::max_value()]).byte(31), 0xff);
+        assert_eq!(U256([0u64, 0, 0, (u64::max_value() >> 8) + 1]).byte(31), 0x01);
+    }
+
+    #[test]
+    pub fn uint256_comp_test() {
+        let small = U256([10u64, 0, 0, 0]);
+        let big = U256([0x8C8C3EE70C644118u64, 0x0209E7378231E632, 0, 0]);
+        let bigger = U256([0x9C8C3EE70C644118u64, 0x0209E7378231E632, 0, 0]);
+        let biggest = U256([0x5C8C3EE70C644118u64, 0x0209E7378231E632, 0, 1]);
+
+        assert!(small < big);
+        assert!(big < bigger);
+        assert!(bigger < biggest);
+        assert!(bigger <= biggest);
+        assert!(biggest <= biggest);
+        assert!(bigger >= big);
+        assert!(bigger >= small);
+        assert!(small <= small);
+    }
+
+    #[test]
+    pub fn uint256_arithmetic_test() {
+        let init = U256::from(0xDEADBEEFDEADBEEFu64);
+        let copy = init;
+
+        let add = init + copy;
+        assert_eq!(add, U256([0xBD5B7DDFBD5B7DDEu64, 1, 0, 0]));
+        // Bitshifts
+        let shl = add << 88;
+        assert_eq!(shl, U256([0u64, 0xDFBD5B7DDE000000, 0x1BD5B7D, 0]));
+        let shr = shl >> 40;
+        assert_eq!(shr, U256([0x7DDE000000000000u64, 0x0001BD5B7DDFBD5B, 0, 0]));
+        // Increment
+        let incr = shr + U256::from(1u64);
+        assert_eq!(incr, U256([0x7DDE000000000001u64, 0x0001BD5B7DDFBD5B, 0, 0]));
+        // Subtraction
+        let sub = incr - init;
+        assert_eq!(sub, U256([0x9F30411021524112u64, 0x0001BD5B7DDFBD5A, 0, 0]));
+        // Multiplication
+        let mult = sub.mul_u32(300);
+        assert_eq!(mult, U256([0x8C8C3EE70C644118u64, 0x0209E7378231E632, 0, 0]));
+        // Division
+        assert_eq!(U256::from(105u8) / U256::from(5u8), U256::from(21u8));
+        let div = mult / U256::from(300u16);
+        assert_eq!(div, U256([0x9F30411021524112u64, 0x0001BD5B7DDFBD5A, 0, 0]));
+        //// TODO: bit inversion
+    }
+
+    #[test]
+    pub fn uint256_extreme_bitshift_test() {
+        //// Shifting a u64 by 64 bits gives an undefined value, so make sure that
+        //// we're doing the Right Thing here
+        let init = U256::from(0xDEADBEEFDEADBEEFu64);
+
+        assert_eq!(init << 64, U256([0, 0xDEADBEEFDEADBEEF, 0, 0]));
+        let add = (init << 64) + init;
+        assert_eq!(add, U256([0xDEADBEEFDEADBEEF, 0xDEADBEEFDEADBEEF, 0, 0]));
+        assert_eq!(add >> 0, U256([0xDEADBEEFDEADBEEF, 0xDEADBEEFDEADBEEF, 0, 0]));
+        assert_eq!(add << 0, U256([0xDEADBEEFDEADBEEF, 0xDEADBEEFDEADBEEF, 0, 0]));
+        assert_eq!(add >> 64, U256([0xDEADBEEFDEADBEEF, 0, 0, 0]));
+        assert_eq!(add << 64, U256([0, 0xDEADBEEFDEADBEEF, 0xDEADBEEFDEADBEEF, 0]));
+    }
+}
+

src/vector.rs

@@ -0,0 +1,34 @@
+
+use std::ptr;
+
+pub trait InsertSlice<T> {
+    fn insert_slice(&mut self, index: usize, elements: &[T]);
+}
+
+/// based on `insert` function implementation from standard library
+impl<T> InsertSlice<T> for Vec<T> {
+    fn insert_slice(&mut self, index: usize, elements: &[T]) {
+        let e_len = elements.len();
+        if e_len == 0 {
+            return;
+        }
+
+        let len = self.len();
+        assert!(index <= len);
+
+        // space for the new element
+        self.reserve(e_len);
+
+        unsafe {
+            {
+                let p = self.as_mut_ptr().offset(index as isize);
+                let ep = elements.as_ptr().offset(0);
+                // shift everything by e_len, to make space
+                ptr::copy(p, p.offset(e_len as isize), len - index);
+                // write new element
+                ptr::copy(ep, p, e_len); 
+            }
+            self.set_len(len + e_len);
+        }
+    }
+}