1 /* 2 Example of instantiating of the WebAssembly module and invoking its exported 3 function. 4 5 You can compile and run this example on Linux with: 6 7 cargo build --release -p wasmtime 8 cc examples/multi.c \ 9 -I crates/c-api/include \ 10 -I crates/c-api/wasm-c-api/include \ 11 target/release/libwasmtime.a \ 12 -lpthread -ldl -lm \ 13 -o multi 14 ./multi 15 16 Note that on Windows and macOS the command will be similar, but you'll need 17 to tweak the `-lpthread` and such annotations. 18 19 Also note that this example was taken from 20 https://github.com/WebAssembly/wasm-c-api/blob/master/example/multi.c 21 originally 22 */ 23 24 #include <stdio.h> 25 #include <stdlib.h> 26 #include <string.h> 27 #include <inttypes.h> 28 #include <wasm.h> 29 #include <wasmtime.h> 30 31 // A function to be called from Wasm code. 32 wasm_trap_t* callback( 33 const wasm_val_t args[], wasm_val_t results[] 34 ) { 35 printf("Calling back...\n"); 36 printf("> %"PRIu32" %"PRIu64"\n", args[0].of.i32, args[1].of.i64); 37 printf("\n"); 38 39 wasm_val_copy(&results[0], &args[1]); 40 wasm_val_copy(&results[1], &args[0]); 41 return NULL; 42 } 43 44 45 // A function closure. 46 wasm_trap_t* closure_callback( 47 void* env, const wasm_val_t args[], wasm_val_t results[] 48 ) { 49 int i = *(int*)env; 50 printf("Calling back closure...\n"); 51 printf("> %d\n", i); 52 53 results[0].kind = WASM_I32; 54 results[0].of.i32 = (int32_t)i; 55 return NULL; 56 } 57 58 59 int main(int argc, const char* argv[]) { 60 // Initialize. 61 printf("Initializing...\n"); 62 wasm_config_t *config = wasm_config_new(); 63 assert(config != NULL); 64 wasmtime_config_wasm_multi_value_set(config, true); 65 wasm_engine_t* engine = wasm_engine_new_with_config(config); 66 wasm_store_t* store = wasm_store_new(engine); 67 68 // Load our input file to parse it next 69 FILE* file = fopen("examples/multi.wat", "r"); 70 if (!file) { 71 printf("> Error loading file!\n"); 72 return 1; 73 } 74 fseek(file, 0L, SEEK_END); 75 size_t file_size = ftell(file); 76 fseek(file, 0L, SEEK_SET); 77 wasm_byte_vec_t wat; 78 wasm_byte_vec_new_uninitialized(&wat, file_size); 79 if (fread(wat.data, file_size, 1, file) != 1) { 80 printf("> Error loading module!\n"); 81 return 1; 82 } 83 fclose(file); 84 85 // Parse the wat into the binary wasm format 86 wasm_byte_vec_t binary, error; 87 if (wasmtime_wat2wasm(engine, &wat, &binary, &error) == 0) { 88 fprintf(stderr, "failed to parse wat %.*s\n", (int) error.size, error.data); 89 return 1; 90 } 91 wasm_byte_vec_delete(&wat); 92 93 // Compile. 94 printf("Compiling module...\n"); 95 wasm_module_t* module = wasm_module_new(store, &binary); 96 if (!module) { 97 printf("> Error compiling module!\n"); 98 return 1; 99 } 100 101 wasm_byte_vec_delete(&binary); 102 103 // Create external print functions. 104 printf("Creating callback...\n"); 105 wasm_functype_t* callback_type = wasm_functype_new_2_2( 106 wasm_valtype_new_i32(), 107 wasm_valtype_new_i64(), 108 wasm_valtype_new_i64(), 109 wasm_valtype_new_i32() 110 ); 111 wasm_func_t* callback_func = 112 wasm_func_new(store, callback_type, callback); 113 114 wasm_functype_delete(callback_type); 115 116 // Instantiate. 117 printf("Instantiating module...\n"); 118 const wasm_extern_t* imports[] = {wasm_func_as_extern(callback_func)}; 119 wasm_instance_t* instance = 120 wasm_instance_new(store, module, imports, NULL); 121 if (!instance) { 122 printf("> Error instantiating module!\n"); 123 return 1; 124 } 125 126 wasm_func_delete(callback_func); 127 128 // Extract export. 129 printf("Extracting export...\n"); 130 wasm_extern_vec_t exports; 131 wasm_instance_exports(instance, &exports); 132 if (exports.size == 0) { 133 printf("> Error accessing exports!\n"); 134 return 1; 135 } 136 const wasm_func_t* run_func = wasm_extern_as_func(exports.data[0]); 137 if (run_func == NULL) { 138 printf("> Error accessing export!\n"); 139 return 1; 140 } 141 142 wasm_module_delete(module); 143 wasm_instance_delete(instance); 144 145 // Call. 146 printf("Calling export...\n"); 147 wasm_val_t args[4]; 148 args[0].kind = WASM_I32; 149 args[0].of.i32 = 1; 150 args[1].kind = WASM_I64; 151 args[1].of.i64 = 2; 152 wasm_val_t results[2]; 153 if (wasm_func_call(run_func, args, results)) { 154 printf("> Error calling function!\n"); 155 return 1; 156 } 157 158 wasm_extern_vec_delete(&exports); 159 160 // Print result. 161 printf("Printing result...\n"); 162 printf("> %"PRIu64" %"PRIu32"\n", 163 results[0].of.i64, results[1].of.i32); 164 165 assert(results[0].kind == WASM_I64); 166 assert(results[0].of.i64 == 2); 167 assert(results[1].kind == WASM_I32); 168 assert(results[1].of.i32 == 1); 169 170 // Shut down. 171 printf("Shutting down...\n"); 172 wasm_store_delete(store); 173 wasm_engine_delete(engine); 174 175 // All done. 176 printf("Done.\n"); 177 return 0; 178 } 179 180