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 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186
use crate::{encode_section, encoding_size, ConstExpr, Encode, Section, SectionId};
/// An encoder for the data section.
///
/// Data sections are only supported for modules.
///
/// # Example
///
/// ```
/// use wasm_encoder::{
/// ConstExpr, DataSection, Instruction, MemorySection, MemoryType,
/// Module,
/// };
///
/// let mut memory = MemorySection::new();
/// memory.memory(MemoryType {
/// minimum: 1,
/// maximum: None,
/// memory64: false,
/// shared: false,
/// page_size_log2: None,
/// });
///
/// let mut data = DataSection::new();
/// let memory_index = 0;
/// let offset = ConstExpr::i32_const(42);
/// let segment_data = b"hello";
/// data.active(memory_index, &offset, segment_data.iter().copied());
///
/// let mut module = Module::new();
/// module
/// .section(&memory)
/// .section(&data);
///
/// let wasm_bytes = module.finish();
/// ```
#[derive(Clone, Default, Debug)]
pub struct DataSection {
bytes: Vec<u8>,
num_added: u32,
}
/// A segment in the data section.
#[derive(Clone, Debug)]
pub struct DataSegment<'a, D> {
/// This data segment's mode.
pub mode: DataSegmentMode<'a>,
/// This data segment's data.
pub data: D,
}
/// A data segment's mode.
#[derive(Clone, Debug)]
pub enum DataSegmentMode<'a> {
/// An active data segment.
Active {
/// The memory this segment applies to.
memory_index: u32,
/// The offset where this segment's data is initialized at.
offset: &'a ConstExpr,
},
/// A passive data segment.
///
/// Passive data segments are part of the bulk memory proposal.
Passive,
}
impl DataSection {
/// Create a new data section encoder.
pub fn new() -> Self {
Self::default()
}
/// The number of data segments in the section.
pub fn len(&self) -> u32 {
self.num_added
}
/// Determines if the section is empty.
pub fn is_empty(&self) -> bool {
self.num_added == 0
}
/// Define a data segment.
pub fn segment<D>(&mut self, segment: DataSegment<D>) -> &mut Self
where
D: IntoIterator<Item = u8>,
D::IntoIter: ExactSizeIterator,
{
match segment.mode {
DataSegmentMode::Passive => {
self.bytes.push(0x01);
}
DataSegmentMode::Active {
memory_index: 0,
offset,
} => {
self.bytes.push(0x00);
offset.encode(&mut self.bytes);
}
DataSegmentMode::Active {
memory_index,
offset,
} => {
self.bytes.push(0x02);
memory_index.encode(&mut self.bytes);
offset.encode(&mut self.bytes);
}
}
let data = segment.data.into_iter();
data.len().encode(&mut self.bytes);
self.bytes.extend(data);
self.num_added += 1;
self
}
/// Define an active data segment.
pub fn active<D>(&mut self, memory_index: u32, offset: &ConstExpr, data: D) -> &mut Self
where
D: IntoIterator<Item = u8>,
D::IntoIter: ExactSizeIterator,
{
self.segment(DataSegment {
mode: DataSegmentMode::Active {
memory_index,
offset,
},
data,
})
}
/// Define a passive data segment.
///
/// Passive data segments are part of the bulk memory proposal.
pub fn passive<D>(&mut self, data: D) -> &mut Self
where
D: IntoIterator<Item = u8>,
D::IntoIter: ExactSizeIterator,
{
self.segment(DataSegment {
mode: DataSegmentMode::Passive,
data,
})
}
/// Copy an already-encoded data segment into this data section.
pub fn raw(&mut self, already_encoded_data_segment: &[u8]) -> &mut Self {
self.bytes.extend_from_slice(already_encoded_data_segment);
self.num_added += 1;
self
}
}
impl Encode for DataSection {
fn encode(&self, sink: &mut Vec<u8>) {
encode_section(sink, self.num_added, &self.bytes);
}
}
impl Section for DataSection {
fn id(&self) -> u8 {
SectionId::Data.into()
}
}
/// An encoder for the data count section.
#[derive(Clone, Copy, Debug)]
pub struct DataCountSection {
/// The number of segments in the data section.
pub count: u32,
}
impl Encode for DataCountSection {
fn encode(&self, sink: &mut Vec<u8>) {
encoding_size(self.count).encode(sink);
self.count.encode(sink);
}
}
impl Section for DataCountSection {
fn id(&self) -> u8 {
SectionId::DataCount.into()
}
}