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/* Copyright 2018 Mozilla Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
use crate::{BinaryReader, ConstExpr, FromReader, GlobalType, Result, SectionLimited};
/// Represents a core WebAssembly global.
#[derive(Debug, Clone)]
pub struct Global<'a> {
/// The global's type.
pub ty: GlobalType,
/// The global's initialization expression.
pub init_expr: ConstExpr<'a>,
}
/// A reader for the global section of a WebAssembly module.
pub type GlobalSectionReader<'a> = SectionLimited<'a, Global<'a>>;
impl<'a> FromReader<'a> for Global<'a> {
fn from_reader(reader: &mut BinaryReader<'a>) -> Result<Self> {
let ty = reader.read()?;
let init_expr = reader.read()?;
Ok(Global { ty, init_expr })
}
}
impl<'a> FromReader<'a> for GlobalType {
fn from_reader(reader: &mut BinaryReader<'a>) -> Result<Self> {
let content_type = reader.read()?;
let flags = reader.read_u8()?;
if reader.shared_everything_threads() {
if flags > 0b11 {
bail!(reader.original_position() - 1, "malformed global flags")
}
} else {
if flags > 0b1 {
bail!(
reader.original_position() - 1,
"malformed mutability -- or shared globals \
require the shared-everything-threads proposal"
)
}
}
Ok(GlobalType {
content_type,
mutable: (flags & 0b01) > 0,
shared: (flags & 0b10) > 0,
})
}
}