docs: string example

Signed-off-by: Henry Gressmann <mail@henrygressmann.de>

3 files changed, 39 insertions, 11 deletions

diff --git a/examples/rust/src/hello.rs b/examples/rust/src/hello.rs
index 34f3c7f..6bb6d97 100644
--- a/examples/rust/src/hello.rs
+++ b/examples/rust/src/hello.rs
@@ -1,18 +1,28 @@
-#![no_std]
 #![no_main]
 
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    core::arch::wasm32::unreachable()
-}
-
 #[link(wasm_import_module = "env")]
 extern "C" {
-    fn printi32(x: i32);
+    fn print_utf8(location: i32, len: i32);
+}
+
+const ARG: &[u8] = &[0u8; 100];
+
+#[no_mangle]
+pub unsafe extern "C" fn arg_ptr() -> i32 {
+    ARG.as_ptr() as i32
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn add_and_print(lh: i32, rh: i32) {
-    printi32(lh + rh);
+pub unsafe extern "C" fn arg_size() -> i32 {
+    ARG.len() as i32
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn hello(len: i32) {
+    let arg = core::str::from_utf8(&ARG[0..len as usize]).unwrap();
+    let res = format!("Hello, {}!", arg).as_bytes().to_vec();
+
+    let len = res.len() as i32;
+    let ptr = res.leak().as_ptr() as i32;
+    print_utf8(ptr, len);
 }
diff --git a/examples/rust/src/print.rs b/examples/rust/src/print.rs
new file mode 100644
index 0000000..34f3c7f
--- /dev/null
+++ b/examples/rust/src/print.rs
@@ -0,0 +1,18 @@
+#![no_std]
+#![no_main]
+
+#[cfg(not(test))]
+#[panic_handler]
+fn panic(_info: &core::panic::PanicInfo) -> ! {
+    core::arch::wasm32::unreachable()
+}
+
+#[link(wasm_import_module = "env")]
+extern "C" {
+    fn printi32(x: i32);
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn add_and_print(lh: i32, rh: i32) {
+    printi32(lh + rh);
+}
diff --git a/examples/rust/src/tinywasm.rs b/examples/rust/src/tinywasm.rs
index 0fb9261..08c8135 100644
--- a/examples/rust/src/tinywasm.rs
+++ b/examples/rust/src/tinywasm.rs
@@ -12,7 +12,7 @@ pub extern "C" fn hello() {
 }
 
 fn run() -> tinywasm::Result<()> {
-    let module = tinywasm::Module::parse_bytes(include_bytes!("../out/hello.wasm"))?;
+    let module = tinywasm::Module::parse_bytes(include_bytes!("../out/print.wasm"))?;
     let mut store = tinywasm::Store::default();
     let mut imports = tinywasm::Imports::new();