asc-wasm

WebAssembly generation in AssemblyScript

The implementation has been carefully written to avoid any runtime support and allocations. All functions are inlined to make linking easier.

Usage

yarn add asc-wasm

import * as wasm from 'asc-wasm/assembly'

let ptr: u32 = 1234;

ptr += wasm.write_magic(ptr);
ptr += wasm.write_version(ptr);
...

APIs

All function return how many bytes they wrote.

• write_section_header(ptr: u32, id: u8, size: u32): u32

Write a section header at ptr.

• write_leb128_u32(ptr: u32, value: u32): u32

Write value as unsigned LEB128 at ptr.

• write_signed_leb128_u32(ptr: u32, value: u32): u32

Write value as signed LEB128 at ptr but value is unsigned.

• leb128_u32_byte_size(value: u32): u32

Calculate the encoded size of value as unsigned LEB128.

• write_vec5<T>(ptr: u32, arg1: T, arg2: T, arg3: T, arg4: T, arg5: T): u32

Write a Vec of constant length at ptr.

• write_magic(ptr: u32): u32

Write WebAssembly magic number at ptr.

• write_version(ptr: u32): u32

Write WebAssembly version at ptr.

• write_i32_const(ptr: u32, value: u32): u32

Write a i32.const instruction with value as immediate at ptr.

• write_end(ptr: u32): u32

Write the end instruction at ptr.