fix: fix branching and count-vowels

runtime/src/main/java/com/dylibso/chicory/runtime/Machine.java

@@ -161,12 +161,12 @@ void eval(List<Instruction> code) throws ChicoryException {
                         }
                     case END:
                         {
-                            frame.blockDepth--;
                             // if this is the last end, then we're done with
                             // the function
                             if (frame.blockDepth == 0) {
                                 break loop;
                             }
+                            frame.blockDepth--;
                             break;
                         }
                     case LOCAL_GET:

runtime/src/test/java/com/dylibso/chicory/runtime/ModuleTest.java

@@ -163,17 +163,19 @@ public void shouldSupportGlobals() {
         assertEquals(42, result.asInt());
     }
 
-    //        @Test
-    //        public void shouldCountVowels() {
-    //            var instance =
-    // Module.build("src/test/resources/wasm/count_vowels.rs.wasm").instantiate();
-    //            var countVowels = instance.getExport("count_vowels");
-    ////            var memory = instance.getMemory();
-    ////            memory.put(0, "Hello World!");
-    ////            var result = countVowels.apply(Value.i32(0));
-    //            var result = countVowels.apply();
-    //            assertEquals(3, result.asInt());
-    //        }
+    @Test
+    public void shouldCountVowels() {
+        var instance = Module.build("src/test/resources/wasm/count_vowels.rs.wasm").instantiate();
+        var alloc = instance.getExport("alloc");
+        var countVowels = instance.getExport("count_vowels");
+        var memory = instance.getMemory();
+        var message = "Hello, World!";
+        var len = message.getBytes().length;
+        var ptr = alloc.apply(Value.i32(len)).asInt();
+        memory.put(ptr, message);
+        var result = countVowels.apply(Value.i32(ptr), Value.i32(len));
+        assertEquals(3, result.asInt());
+    }
 
     @Test
     public void shouldRunBasicCProgram() {

runtime/src/test/resources/wasm/count_vowels.rs

@@ -1,8 +1,27 @@
 const VOWELS: &[char] = &['a', 'A', 'e', 'E', 'i', 'I', 'o', 'O', 'u', 'U'];
 
+use std::mem;
+use std::slice;
+use std::str;
+
+#[no_mangle]
+pub extern "C" fn alloc(len: i32) -> *const u8 {
+    let mut buf = Vec::with_capacity(len as usize);
+    let ptr = buf.as_mut_ptr();
+    // tell Rust not to clean this up
+    mem::forget(buf);
+    ptr
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn dealloc(ptr: &mut u8) {
+    let _ = Vec::from_raw_parts(ptr, 0, 1024);
+}
+
 #[no_mangle]
-pub extern fn count_vowels() -> i32 {
-    let s = String::from("Hello World!");
+pub extern fn count_vowels(ptr: i32, len: i32) -> i32 {
+    let bytes = unsafe { slice::from_raw_parts(ptr as *const u8, len as usize) };
+    let s = str::from_utf8(bytes).unwrap();
     let mut count: i32 = 0;
     for ch in s.chars() {
         if VOWELS.contains(&ch) {