Eable post-MVP feature wasm-c-api (#315)

samples/wasm-c-api/src/callback.c

@@ -0,0 +1,168 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+
+#include "wasm_c_api.h"
+
+#define own
+
+// Print a Wasm value
+void wasm_val_print(wasm_val_t val) {
+  switch (val.kind) {
+    case WASM_I32: {
+      printf("%" PRIu32, val.of.i32);
+    } break;
+    case WASM_I64: {
+      printf("%" PRIu64, val.of.i64);
+    } break;
+    case WASM_F32: {
+      printf("%f", val.of.f32);
+    } break;
+    case WASM_F64: {
+      printf("%g", val.of.f64);
+    } break;
+    case WASM_ANYREF:
+    case WASM_FUNCREF: {
+      if (val.of.ref == NULL) {
+        printf("null");
+      } else {
+        printf("ref(%p)", val.of.ref);
+      }
+    } break;
+  }
+}
+
+// A function to be called from Wasm code.
+own wasm_trap_t* print_callback(
+  const wasm_val_t args[], wasm_val_t results[]
+) {
+  printf("Calling back...\n> ");
+  wasm_val_print(args[0]);
+  printf("\n");
+
+  wasm_val_copy(&results[0], &args[0]);
+  return NULL;
+}
+
+
+// A function closure.
+own wasm_trap_t* closure_callback(
+  void* env, const wasm_val_t args[], wasm_val_t results[]
+) {
+  int i = *(int*)env;
+  printf("Calling back closure...\n");
+  printf("> %d\n", i);
+
+  results[0].kind = WASM_I32;
+  results[0].of.i32 = (int32_t)i;
+  return NULL;
+}
+
+
+int main(int argc, const char* argv[]) {
+  // Initialize.
+  printf("Initializing...\n");
+  wasm_engine_t* engine = wasm_engine_new();
+  wasm_store_t* store = wasm_store_new(engine);
+
+  // Load binary.
+  printf("Loading binary...\n");
+  FILE* file = fopen("callback.wasm", "rb");
+  if (!file) {
+    printf("> Error loading module!\n");
+    return 1;
+  }
+  fseek(file, 0L, SEEK_END);
+  size_t file_size = ftell(file);
+  fseek(file, 0L, SEEK_SET);
+  wasm_byte_vec_t binary;
+  wasm_byte_vec_new_uninitialized(&binary, file_size);
+  if (fread(binary.data, file_size, 1, file) != 1) {
+    printf("> Error loading module!\n");
+    return 1;
+  }
+  fclose(file);
+
+  // Compile.
+  printf("Compiling module...\n");
+  own wasm_module_t* module = wasm_module_new(store, &binary);
+  if (!module) {
+    printf("> Error compiling module!\n");
+    return 1;
+  }
+
+  wasm_byte_vec_delete(&binary);
+
+  // Create external print functions.
+  printf("Creating callback...\n");
+  own wasm_functype_t* print_type = wasm_functype_new_1_1(wasm_valtype_new_i32(), wasm_valtype_new_i32());
+  own wasm_func_t* print_func = wasm_func_new(store, print_type, print_callback);
+
+  int i = 42;
+  own wasm_functype_t* closure_type = wasm_functype_new_0_1(wasm_valtype_new_i32());
+  own wasm_func_t* closure_func = wasm_func_new_with_env(store, closure_type, closure_callback, &i, NULL);
+
+  wasm_functype_delete(print_type);
+  wasm_functype_delete(closure_type);
+
+  // Instantiate.
+  printf("Instantiating module...\n");
+  const wasm_extern_t* imports[] = {
+    wasm_func_as_extern(print_func), wasm_func_as_extern(closure_func)
+  };
+  own wasm_instance_t* instance =
+    wasm_instance_new(store, module, imports, NULL);
+  if (!instance) {
+    printf("> Error instantiating module!\n");
+    return 1;
+  }
+
+  wasm_func_delete(print_func);
+  wasm_func_delete(closure_func);
+
+  // Extract export.
+  printf("Extracting export...\n");
+  own wasm_extern_vec_t exports;
+  wasm_instance_exports(instance, &exports);
+  if (exports.size == 0) {
+    printf("> Error accessing exports!\n");
+    return 1;
+  }
+  const wasm_func_t* run_func = wasm_extern_as_func(exports.data[0]);
+  if (run_func == NULL) {
+    printf("> Error accessing export!\n");
+    return 1;
+  }
+
+  wasm_module_delete(module);
+  wasm_instance_delete(instance);
+
+  // Call.
+  printf("Calling export...\n");
+  wasm_val_t args[2];
+  args[0].kind = WASM_I32;
+  args[0].of.i32 = 3;
+  args[1].kind = WASM_I32;
+  args[1].of.i32 = 4;
+  wasm_val_t results[1];
+  if (wasm_func_call(run_func, args, results)) {
+    printf("> Error calling function!\n");
+    return 1;
+  }
+
+  wasm_extern_vec_delete(&exports);
+
+  // Print result.
+  printf("Printing result...\n");
+  printf("> %u\n", results[0].of.i32);
+
+  // Shut down.
+  printf("Shutting down...\n");
+  wasm_store_delete(store);
+  wasm_engine_delete(engine);
+
+  // All done.
+  printf("Done.\n");
+  return 0;
+}