webassembly.toml

name = "WebAssembly"
entrypoint = "main.wat"
extensions = [
  "wat"
]
packages = [
]
setup = [
  "wget https://github.com/wasmerio/wasmer/releases/download/0.14.0/wasmer-linux-amd64.tar.gz -O /tmp/wasmer.tar.gz",
  "mkdir /usr/local/wasmer",
  "tar -xvf /tmp/wasmer.tar.gz -C /usr/local/wasmer --strip-components=1",
  "ln -s /usr/local/wasmer/wasmer /usr/local/bin/wasmer",
  "rm /tmp/wasmer.tar.gz"
]


[run]
command = [
  "wasmer",
  "run",
  "main.wat"
]

[tests]

  [tests.hello]
  code = """;; wat2wasm main.wat

(module $hello
    ;; Import the required fd_write WASI function which will write the given io vectors to stdout
    ;; The function signature for fd_write is:
    ;; (File Descriptor, *iovs, iovs_len, nwritten) -> Returns number of bytes written
    (import "wasi_unstable" "fd_write"
        (func $fd_write (param i32 i32 i32 i32) (result i32))
    )

    (memory 1)
    (export "memory" (memory 0))

    ;; Write 'hello world\\n' to memory at an offset of 8 bytes
    ;; Note the trailing newline which is required for the text to appear
    (data (i32.const 8) "Hello, World")

    (func $main (export "_start")
        ;; Creating a new io vector within linear memory
        (i32.store (i32.const 0) (i32.const 8))  ;; iov.iov_base - This is a pointer to the start of the 'hello world\\n' string
        (i32.store (i32.const 4) (i32.const 12))  ;; iov.iov_len - The length of the 'hello world\\n' string

        (call $fd_write
            (i32.const 1) ;; file_descriptor - 1 for stdout
            (i32.const 0) ;; *iovs - The pointer to the iov array, which is stored at memory location 0
            (i32.const 1) ;; iovs_len - We're printing 1 string stored in an iov - so one.
            (i32.const 20) ;; nwritten - A place in memory to store the number of bytes writen
        )
        drop ;; Discard the number of bytes written from the top the stack
    )
)
"""
  output = "Hello, World"