variable_len_reader/asynchronous/
write_varint.rs

1macro_rules! write_varint_future {
2    ($primitive: ty, $future: ident) => {
3        write_varint_future!(f cfg(feature = "async_varint"), $primitive, $future, u8, WriteU8Raw);
4    };
5    (f $feature: meta, $primitive: ty, $future: ident, $internal: ty, $inner_future: ident) => {
6        #[$feature]
7        $crate::pin_project_lite::pin_project! {
8            #[cfg_attr(docsrs, doc($feature))]
9            #[derive(Debug)]
10            #[project(!Unpin)]
11            #[must_use = "futures do nothing unless you `.await` or poll them"]
12            pub struct $future<'a, W: ?Sized> {
13                value: $primitive,
14                position: usize,
15                ok: bool,
16                #[pin]
17                inner: $inner_future<'a, W>,
18            }
19        }
20        #[$feature]
21        impl<'a, W: ?Sized> WriterFuture<'a, W, $primitive> for $future<'a, W> {
22            fn new(writer: &'a mut W, buf: $primitive) -> Self {
23                let (value, current, position) = Self::_extra(buf, 0);
24                Self { value, position, ok: false, inner: $inner_future::new(writer, current) }
25            }
26            fn reset(self: Pin<&mut Self>, buf: $primitive) {
27                let me = self.project();
28                let (value, current, position) = Self::_extra(buf, 0);
29                *me.value = value;
30                *me.position = position;
31                *me.ok = false;
32                me.inner.reset(current);
33            }
34        }
35        #[$feature]
36        impl<'a, W: AsyncVariableWriter + Unpin + ?Sized> Future for $future<'a, W> {
37            type Output = ::core::result::Result<(), W::Error>;
38
39            fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
40                let mut me = self.project();
41                if *me.ok { return Poll::Ready(Ok(())); }
42                loop {
43                    ::core::task::ready!(me.inner.as_mut().poll(cx))?;
44                    if *me.value == 0 {
45                        *me.ok = true;
46                        return Poll::Ready(Ok(()));
47                    }
48                    let (value, current, position) = Self::_extra(*me.value, *me.position);
49                    *me.value = value;
50                    *me.position = position;
51                    me.inner.as_mut().reset(current);
52                }
53            }
54        }
55        #[$feature]
56        #[allow(arithmetic_overflow)] // Safety: only used internally.
57        impl<'a, W: ?Sized> $future<'a, W> {
58            fn _extra(value: $primitive, position: usize) -> ($primitive, $internal, usize) {
59                const NUM_BITS: $internal = <$internal>::MAX >> 1;
60                const SIGN_BIT: $internal = NUM_BITS + 1;
61                const POS_OFFSET: usize = (<$internal>::BITS - 1) as usize;
62                if (value & NUM_BITS as $primitive) != value {
63                    (value >> POS_OFFSET, ((value & (NUM_BITS as $primitive)) as $internal) | SIGN_BIT, position + POS_OFFSET)
64                } else {
65                    (0, value as $internal, position + POS_OFFSET)
66                }
67            }
68        }
69    };
70}
71macro_rules! write_varint_func {
72    ($primitive: ty, $future: ident, $func: ident) => {
73        write_varint_func!(f cfg(feature = "async_varint"), $primitive, $future, $func);
74    };
75    (f $feature: meta, $primitive: ty, $future: ident, $func: ident) => {
76        write_wrap_func!(f $feature, $primitive, $future, $func);
77    };
78}
79
80macro_rules! define_write_varint_future {
81    () => {
82        write_varint_future!(u16, WriteU16Varint);
83        write_varint_future!(u32, WriteU32Varint);
84        write_varint_future!(u64, WriteU64Varint);
85        write_varint_future!(u128, WriteU128Varint);
86    };
87}
88macro_rules! define_write_varint_func {
89    () => {
90        write_varint_func!(u16, WriteU16Varint, write_u16_varint);
91        write_varint_func!(u32, WriteU32Varint, write_u32_varint);
92        write_varint_func!(u64, WriteU64Varint, write_u64_varint);
93        write_varint_func!(u128, WriteU128Varint, write_u128_varint);
94    };
95}
96
97define_write_varint_future!();
98
99#[cfg(all(feature = "async_varint", not(feature = "async_raw")))]
100compile_error!("developer error: please check Cargo.toml");
variable_len_reader/asynchronous/write_varint.rs

variable_len_reader/asynchronous/
write_varint.rs
