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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include "wasm.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_EXTERNREF:
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_vec_t* args, wasm_val_vec_t* results
) {
printf("Calling back...\n> ");
wasm_val_print(args->data[0]);
printf("\n");
wasm_val_copy(&results->data[0], &args->data[0]);
return NULL;
}
// A function closure.
own wasm_trap_t* closure_callback(
void* env, const wasm_val_vec_t* args, wasm_val_vec_t* results
) {
int i = *(int*)env;
printf("Calling back closure...\n");
printf("> %d\n", i);
results->data[0].kind = WASM_I32;
results->data[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");
wasm_extern_t* externs[] = {
wasm_func_as_extern(print_func), wasm_func_as_extern(closure_func)
};
wasm_extern_vec_t imports = WASM_ARRAY_VEC(externs);
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 as[2] = { WASM_I32_VAL(3), WASM_I32_VAL(4) };
wasm_val_t rs[1] = { WASM_INIT_VAL };
wasm_val_vec_t args = WASM_ARRAY_VEC(as);
wasm_val_vec_t results = WASM_ARRAY_VEC(rs);
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", rs[0].of.i32);
// Shut down.
printf("Shutting down...\n");
wasm_store_delete(store);
wasm_engine_delete(engine);
// All done.
printf("Done.\n");
return 0;
}
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