fidl_next_codec/wire/
table.rs

1// Copyright 2024 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use core::mem::MaybeUninit;
6
7use munge::munge;
8
9use crate::{
10    DecodeError, Decoder, DecoderExt as _, Owned, Slot, WireEnvelope, WirePointer, WireU64,
11    ZeroPadding,
12};
13
14/// A FIDL table
15#[repr(C)]
16pub struct WireTable {
17    len: WireU64,
18    ptr: WirePointer<WireEnvelope>,
19}
20
21unsafe impl ZeroPadding for WireTable {
22    #[inline]
23    fn zero_padding(_: &mut MaybeUninit<Self>) {
24        // Wire tables have no padding
25    }
26}
27
28impl WireTable {
29    /// Encodes that a table contains `len` values in a slot.
30    #[inline]
31    pub fn encode_len(out: &mut MaybeUninit<Self>, len: usize) {
32        munge!(let Self { len: table_len, ptr } = out);
33        table_len.write(WireU64(len.try_into().unwrap()));
34        WirePointer::encode_present(ptr);
35    }
36
37    /// Decodes the fields of the table with a decoding function.
38    ///
39    /// The decoding function receives the ordinal of the field, its slot, and the decoder.
40    #[inline]
41    pub fn decode_with<D: Decoder + ?Sized>(
42        slot: Slot<'_, Self>,
43        mut decoder: &mut D,
44        f: impl Fn(i64, Slot<'_, WireEnvelope>, &mut D) -> Result<(), DecodeError>,
45    ) -> Result<(), DecodeError> {
46        munge!(let Self { len, mut ptr } = slot);
47
48        if WirePointer::is_encoded_present(ptr.as_mut())? {
49            let mut envelopes = decoder.take_slice_slot::<WireEnvelope>(**len as usize)?;
50            let envelopes_ptr = envelopes.as_mut_ptr().cast::<WireEnvelope>();
51
52            for i in 0..**len as usize {
53                let mut envelope = envelopes.index(i);
54                if !WireEnvelope::is_encoded_zero(envelope.as_mut()) {
55                    f((i + 1) as i64, envelope, decoder)?;
56                }
57            }
58
59            let envelopes = unsafe { Owned::new_unchecked(envelopes_ptr) };
60            WirePointer::set_decoded(ptr, envelopes.into_raw());
61        } else if **len != 0 {
62            return Err(DecodeError::InvalidOptionalSize(**len));
63        }
64
65        Ok(())
66    }
67
68    /// Returns a reference to the envelope for the given ordinal, if any.
69    #[inline]
70    pub fn get(&self, ordinal: usize) -> Option<&WireEnvelope> {
71        if ordinal == 0 || ordinal > *self.len as usize {
72            return None;
73        }
74
75        let envelope = unsafe { &*self.ptr.as_ptr().add(ordinal - 1) };
76        (!envelope.is_zero()).then_some(envelope)
77    }
78}
fidl_next_codec/wire/table.rs

fidl_next_codec/wire/
table.rs
