From 970da5376491712089e46b4ff4d27291a02bfa18 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Wed, 28 Jun 2023 20:30:54 +0100
Subject: Get hello-world example working on WASM

---
 runtime/src/shed.c | 27 +++++++++++++++++++++++++++
 runtime/src/shed.h |  8 +++++++-
 2 files changed, 34 insertions(+), 1 deletion(-)

(limited to 'runtime/src')

diff --git a/runtime/src/shed.c b/runtime/src/shed.c
index cf5af0bd..2b69eeae 100644
--- a/runtime/src/shed.c
+++ b/runtime/src/shed.c
@@ -24,6 +24,33 @@ void* shed__runtime__alloc(uint32_t size) {
     return wasm_memory_grow((size + PAGE_SIZE - 1) / PAGE_SIZE);
 }
 
+typedef struct __wasi_ciovec_t {
+    uint8_t * buf;
+    size_t buf_len;
+} __wasi_ciovec_t;
+
+uint16_t wasi_fd_write(uint32_t fd, __wasi_ciovec_t* iovs_ptr, uint32_t iovs_len, uint32_t *nwritten)
+    __attribute__((
+        __import_module__("wasi_snapshot_preview1"),
+        __import_name__("fd_write"),
+    ));
+
+ShedObject shed__runtime__print(ShedClosurePointer closurePointer, ShedString value) {
+    uint32_t stdout = 1;
+    __wasi_ciovec_t iov = {.buf = value->data, .buf_len = value->length};
+    uint32_t iovs_len = 1;
+    uint32_t nwritten;
+    wasi_fd_write(stdout, &iov, iovs_len, &nwritten);
+    return shed_unit;
+}
+
+// TODO: Work out a good way to access the variable directly from our generated
+// WASM (or perhaps just expose this as a builtin module and use the import
+// machinery)?
+ShedObject shed__runtime__print_closure__get() {
+    return (ShedObject) &shed__runtime__print_closure;
+}
+
 #else
 
 void* shed__runtime__alloc(uint64_t size) {
diff --git a/runtime/src/shed.h b/runtime/src/shed.h
index 1fd8f44d..313dd3bf 100644
--- a/runtime/src/shed.h
+++ b/runtime/src/shed.h
@@ -3,12 +3,18 @@
 
 #include <stdint.h>
 
+#ifdef __WASM__
+typedef uint32_t ShedObject;
+typedef uint32_t StringLength;
+#else
 typedef uint64_t ShedObject;
+typedef uint64_t StringLength;
+#endif
 
 extern ShedObject const shed_unit;
 
 struct ShedString {
-    uint64_t length;
+    StringLength length;
     uint8_t data[];
 };
 
-- 
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