Working hello world

.gitignore

@@ -1,3 +1,2 @@
-intermediate.wat
-output.wasmu
-src
+./intermediate.wat
+./output.wasmu

build.sh

@@ -31,4 +31,13 @@ echo "$EPILOGUE" >> $INTERMEDIATE
 
 # test file
 wasmer compile -o ./output.wasmu $INTERMEDIATE
-
+result=$?
+
+if [ 0 -ne $result ]; then
+  echo "Build failed, printing generated wasm:"
+  cat $INTERMEDIATE
+  exit $?
+else
+  echo "Build succeeded, running:"
+  wasmer run ./output.wasmu
+fi

src/entrypoint.wat

@@ -1,19 +1,11 @@
+(data $hello (i32.const 20) "Hello world.\0A")
+(import "wasi_unstable" "proc_exit" (func $proc_exit (param i32)))
 (func $start (export "_start") (result i32)
-  i32.const 5
-  i32.const 4
-  call $test
-
-  i32.load $memory i32.const 0
+  i32.const 20 ;; location
+  i32.const 13 ;; length
+  call $print
 
   call $proc_exit
-  
   unreachable
 )
 
-(import "wasi_unstable" "proc_exit" (func $proc_exit (param i32))) 
-
-(func $test (param $a i32) (param $b i32) (result i32)
-  local.get $a
-  local.get $b
-  i32.add
-)

src/io.wat

@@ -0,0 +1,27 @@
+;; Currently using a hard-coded struct at location 0
+(import "wasi_unstable" "fd_write" (func $fd_write (param $file_descriptor i32) (param $io_vectors i32) (param $io_vecnum i32) (param $num_written_ptr i32) (result i32)))
+
+(func $print (param $location i32) (param $length i32) (result i32)
+  ;; create struct at location 0
+  i32.const 0
+  local.get $location
+  i32.store
+
+  i32.const 4
+  local.get $length
+  i32.store
+
+  ;; file descriptor
+  i32.const 1
+
+  ;; iovs array pointer
+  i32.const 0
+
+  ;; iovs array length
+  i32.const 1
+
+  ;; where to write length written
+  i32.const 200
+
+  call $fd_write
+)