Struct wasm_encoder::CodeSection[−][src]

pub struct CodeSection { /* fields omitted */ }

Expand description

An encoder for the code section.

Example

use wasm_encoder::{
    CodeSection, Function, FunctionSection, Instruction, Module,
    TypeSection, ValType
};

let mut types = TypeSection::new();
types.function(vec![], vec![ValType::I32]);

let mut functions = FunctionSection::new();
let type_index = 0;
functions.function(type_index);

let locals = vec![];
let mut func = Function::new(locals);
func.instruction(&Instruction::I32Const(42));
let mut code = CodeSection::new();
code.function(&func);

let mut module = Module::new();
module
    .section(&types)
    .section(&functions)
    .section(&code);

let wasm_bytes = module.finish();

Implementations

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impl CodeSection

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pub fn new() -> CodeSection

Create a new code section encoder.

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pub fn len(&self) -> u32

How many function bodies have been defined inside this section so far?

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pub fn function(&mut self, func: &Function) -> &mut Self

Write a function body into this code section.

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pub fn raw(&mut self, data: &[u8 ]) -> &mut Self

Add a raw byte slice into this code section as a function body.

The length prefix of the function body will be automatically prepended, and should not be included in the raw byte slice.

Example

You can use the raw method to copy an already-encoded function body into a new code section encoder:

//                  id, size, # entries, entry
let code_section = [10, 6,    1,         4, 0, 65, 0, 11];

// Parse the code section.
let mut reader = wasmparser::CodeSectionReader::new(&code_section, 0).unwrap();
let body = reader.read().unwrap();
let body_range = body.range();

// Add the body to a new code section encoder by copying bytes rather
// than re-parsing and re-encoding it.
let mut encoder = wasm_encoder::CodeSection::new();
encoder.raw(&code_section[body_range.start..body_range.end]);