rudp 0.2.1

State-wrapper for UdpSockets to implement RUDP protocol. Allows per-message selection of message guarantees on a spectrum from UDP-like to TCP-like.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94


use byteorder::{ReadBytesExt, WriteBytesExt, BigEndian};
use std::{
    self,
    io,
    cmp::Ordering,
};

pub const HALF: u32 = std::u32::MAX/2;

#[derive(Copy, Clone, Hash, PartialEq, Eq)]
pub struct ModOrd(u32);
impl ModOrd {
    pub const ZERO: Self = ModOrd(1);
    pub const BEFORE_ZERO: Self = ModOrd(0xFFFF_FFFF);
    pub const SPECIAL: Self = ModOrd(0);

    pub const BYTES: usize = 4;

    pub fn new_plus(self, num: u32) -> Self {
        assert!(!self.special());
    	ModOrd({
            let x = self.0.wrapping_add(num);
            if x < self.0 {
                // it wrapped around!
                x + 1
            } else {
                x
            }
        })
    }

    pub fn abs_difference(self, other: Self) -> u32 {
        if self.0 > other.0 {
            self.0-other.0
        } else {
            other.0-self.0
        }
    }

    pub fn new_minus(self, num: u32) -> Self {
        assert!(!self.special());
        ModOrd({
            let x = self.0.wrapping_sub(num);
            if x > self.0 {
                // it wrapped around!
                x + 1
            } else {
                x
            }
        })
    }
    pub fn read_from<R: io::Read>(mut r:R) -> Result<ModOrd, io::Error> {
    	r.read_u32::<BigEndian>().map(|x| ModOrd(x))
    }
    pub fn write_to<W: io::Write>(self, mut w:W) -> Result<(), io::Error> {
    	w.write_u32::<BigEndian>(self.0)
    }

    #[inline(always)]
    pub fn special(self) -> bool {
        self == Self::SPECIAL
    }
}

use std::fmt;

impl fmt::Debug for ModOrd {
    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        if self.0 == 0 {
            write!(f, "(special)")
        } else {
            write!(f, "{}~", self.0)
        }
    }
}

use std::cmp;

impl std::cmp::PartialOrd for ModOrd {
    fn partial_cmp(&self, rhs: &Self) -> Option<cmp::Ordering> {
        let (s1, s2) = (self.0, rhs.0);
        if self.special() || rhs.special() {
            None
        } else if s1 == s2 {
            Some(Ordering::Equal)
        } else if (s1 > s2 && s1 - s2 <= HALF) 
               || (s1 < s2 && s2 - s1  > HALF) {
            Some(Ordering::Greater)
        } else {
            Some(Ordering::Less)
        }
    }
}