land/userland/src/lib/fileops.wast

(module
 ;; import functions from env
 (func $close  (import "env" "close")  (param i32)         (result i32))
 (func $open   (import "env" "open")   (param i32 i32)     (result i32))
 (func $write  (import "env" "write")  (param i32 i32 i32) (result i32))
 (func $read   (import "env" "read")   (param i32 i32 i32) (result i32))
 (func $istty  (import "env" "isatty") (param i32)         (result i32))
 (func $unlink (import "env" "unlink") (param i32)         (result i32))

 ;; memory
 (memory $mem 1)

 ;; constants
 (data (i32.const 200) "data")
 (data (i32.const 230) "Hello, world!\n")

 ;; functions
 (func $openFile (result i32)
       ;; open stdout
       (i32.const 200)
       (i32.const 42)
       (call $open))

 (func $writeHelloWorld (param $fd i32)
       ;; write hello world
       (get_local $fd)
       (i32.const 230)
       (i32.const 14)
       (call $write)
       (drop))

 (func $readHello (param $fd i32)
       ;; read hello world
       (get_local $fd)
       (i32.const 255)
       (i32.const 14)
       (call $read)
       (drop))

 (func $removeFile
       (i32.const 200)
       (call $unlink)
       (drop))

 (func $main (result i32)
       (local $fd i32)

       ;; set $fd to the file descriptor
       (call $openFile)
       (set_local $fd)

       (get_local $fd)
       (call $writeHelloWorld)
       ;; close file
       (get_local $fd)
       (call $close)

       ;; set $fd to the new file descriptor
       (call $openFile)
       (set_local $fd)

       ;; read Hello, World
       (get_local $fd)
       (call $readHello)

       ;; istty
       (get_local $fd)
       (call $istty)
       (drop)

       ;; close file again
       (get_local $fd)
       (call $close)

       ;; unlink filename
       (call $removeFile)

       ;; return 0
       (i32.const 0)
       (set_local $fd)
       (drop))

 (export "main" (func $main)))