garando_syntax2 0.1.0

Backport of libsyntax
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

#[inline]
/// encodes an integer using unsigned leb128 encoding and stores
/// the result using a callback function.
///
/// The callback `write` is called once for each position
/// that is to be written to with the byte to be encoded
/// at that position.
pub fn write_unsigned_leb128_to<W>(mut value: u128, mut write: W) -> usize
where
    W: FnMut(usize, u8),
{
    let mut position = 0;
    loop {
        let mut byte = (value & u128::from(0x7Fu64)) as u8;
        value >>= 7;
        if value != u128::from(0u64) {
            byte |= 0x80;
        }

        write(position, byte);
        position += 1;

        if value == u128::from(0u64) {
            break;
        }
    }

    position
}

#[inline]
/// encodes an integer using signed leb128 encoding and stores
/// the result using a callback function.
///
/// The callback `write` is called once for each position
/// that is to be written to with the byte to be encoded
/// at that position.
pub fn write_signed_leb128_to<W>(mut value: i128, mut write: W) -> usize
where
    W: FnMut(usize, u8),
{
    let mut position = 0;

    loop {
        let mut byte = (value as u8) & 0x7f;
        value >>= 7;
        let more = !(((value == i128::from(0)) && ((byte & 0x40) == 0))
            || ((value == i128::from(-1)) && ((byte & 0x40) != 0)));

        if more {
            byte |= 0x80; // Mark this byte to show that more bytes will follow.
        }

        write(position, byte);
        position += 1;

        if !more {
            break;
        }
    }
    position
}