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118 lines
3.0 KiB
118 lines
3.0 KiB
/*
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Example of instantiating of the WebAssembly module and invoking its exported
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function.
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You can compile and run this example on Linux with:
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cargo build --release -p wasmtime
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cc examples/gcd.c \
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-I crates/c-api/include \
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-I crates/c-api/wasm-c-api/include \
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target/release/libwasmtime.a \
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-lpthread -ldl -lm \
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-o gcd
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./gcd
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Note that on Windows and macOS the command will be similar, but you'll need
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to tweak the `-lpthread` and such annotations.
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*/
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <wasm.h>
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#include <wasmtime.h>
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static void print_trap(wasm_trap_t *trap);
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int main() {
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int ret = 0;
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// Set up our context
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wasm_engine_t *engine = wasm_engine_new();
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assert(engine != NULL);
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wasm_store_t *store = wasm_store_new(engine);
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assert(store != NULL);
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// Load our input file to parse it next
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FILE* file = fopen("examples/gcd.wat", "r");
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if (!file) {
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printf("> Error loading file!\n");
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return 1;
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}
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fseek(file, 0L, SEEK_END);
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size_t file_size = ftell(file);
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fseek(file, 0L, SEEK_SET);
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wasm_byte_vec_t wat;
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wasm_byte_vec_new_uninitialized(&wat, file_size);
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if (fread(wat.data, file_size, 1, file) != 1) {
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printf("> Error loading module!\n");
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return 1;
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}
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fclose(file);
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// Parse the wat into the binary wasm format
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wasm_byte_vec_t wasm, error;
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if (wasmtime_wat2wasm(&wat, &wasm, &error) == 0) {
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fprintf(stderr, "failed to parse wat %.*s\n", (int) error.size, error.data);
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goto free_store;
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}
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wasm_byte_vec_delete(&wat);
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// Compile and instantiate our module
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wasm_module_t *module = wasm_module_new(store, &wasm);
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wasm_byte_vec_delete(&wasm);
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assert(module != NULL);
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wasm_trap_t *trap = NULL;
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wasm_instance_t *instance = wasm_instance_new(store, module, NULL, &trap);
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if (instance == NULL) {
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print_trap(trap);
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goto free_module;
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}
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// Lookup our `gcd` export function
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wasm_extern_vec_t externs;
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wasm_instance_exports(instance, &externs);
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assert(externs.size == 1);
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wasm_func_t *gcd = wasm_extern_as_func(externs.data[0]);
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assert(gcd != NULL);
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// And call it!
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int a = 6;
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int b = 27;
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wasm_val_t params[2];
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wasm_val_t results[1];
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params[0].kind = WASM_I32;
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params[0].of.i32 = a;
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params[1].kind = WASM_I32;
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params[1].of.i32 = b;
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trap = wasm_func_call(gcd, params, results);
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if (trap != NULL) {
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print_trap(trap);
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goto free_instance;
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}
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assert(results[0].kind == WASM_I32);
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printf("gcd(%d, %d) = %d\n", a, b, results[0].of.i32);
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// Clean up after ourselves at this point
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ret = 0;
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free_instance:
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wasm_extern_vec_delete(&externs);
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wasm_instance_delete(instance);
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free_module:
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wasm_module_delete(module);
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free_store:
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wasm_store_delete(store);
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wasm_engine_delete(engine);
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return ret;
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}
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static void print_trap(wasm_trap_t *trap) {
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assert(trap != NULL);
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wasm_message_t message;
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wasm_trap_message(trap, &message);
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fprintf(stderr, "failed to instantiate module %.*s\n", (int) message.size, message.data);
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wasm_byte_vec_delete(&message);
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wasm_trap_delete(trap);
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}
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