TOC

.c编译成.wasm

  1. 第一个工具: wasmcc
    安装
    curl https://raw.githubusercontent.com/wasienv/wasienv/master/install.sh | sh
    https://github.com/wasienv/wasienv
    其中安装完成之后会包含很多个工具,wasirun可以运行wasm代码
$ wasirun hello.wasm  
Hello wasi  
  1. emscripten
    https://segmentfault.com/a/1190000014208777
git clone https://github.com/juj/emsdk.git  
cd emsdk  
emsdk update  
emsdk install latest  
emsdk activate latest  
//如果没有出现emcc命令:  
source ./emsdk_env.sh  

编译命令:emcc hello.c -s WASM=1 -o hello.wasm

c代码调用wasm代码

https://docs.wasmer.io/integrations/c/setup
环境设置:

# Extract the contents to a dir  
mkdir wasmer-c-api  
tar -C wasmer-c-api -zxvf wasmer-c-api*.tar.gz  
  
export WASMER_C_API=`pwd`/wasmer-c-api  
  
# Update LD_LIBRARY_PATH to link against the libwasmer.so in the examples  
export LD_LIBRARY_PATH=`pwd`/wasmer-c-api/lib/:$LD_LIBRARY_PATH  

编译命令:

静态链接:gcc test.c -I${WASMER_C_API}/include -L${WASMER_C_API}/lib -lwasmer -o test  
动态链接:gcc -static main.c -I${WASMER_C_API}/include -L${WASMER_C_API}/lib -lwasmer -lpthread -lm -ldl -o main  
  1. 例子
    在这里有很多wasi使用的例子
    https://docs.wasmer.io/integrations/c/setup
    但是没看见直接运行整个wasm代码的(例子是调用wasm函数的)
// wasm部分  
#include<stdio.h>  
  
int main()  
{  
char s[20] = {0};  
scanf("%s", s);  
puts(s);  
return 0;  
}  
// c部分  
#include <stdio.h>  
#include "wasmer.h"  
#include <assert.h>  
#include <stdint.h>  
  
// Function to print the most recent error string from Wasmer if we have them  
void print_wasmer_error()  
{  
int error_len = wasmer_last_error_length();  
char *error_str = malloc(error_len);  
wasmer_last_error_message(error_str, error_len);  
printf("Error: `%s`\n", error_str);  
}  
  
int main()  
{  
FILE *file = fopen("hello.wasm", "r");  
assert(file != NULL);  
fseek(file, 0, SEEK_END);  
long len = ftell(file);  
uint8_t *bytes = (uint8_t*)malloc(len);  
fseek(file, 0, SEEK_SET);  
fread(bytes, 1, len, file);  
fclose(file);  
  
wasmer_module_t *module = NULL;  
wasmer_result_t compile_result = wasmer_compile(&module, bytes, len);  
if (compile_result != WASMER_OK)  
{  
    print_wasmer_error();  
    return -1;  
}  
wasmer_import_object_t *wasi_import_obj = wasmer_wasi_generate_default_import_object();  
  
// find out what version of WASI the module is  
Version wasi_version = wasmer_wasi_get_version(module);  
// char* progname = "ProgramName";  
// wasmer_byte_array args[] = { { .bytes = progname; .bytes_len = sizeof(progname); } };  
wasmer_import_object_t * import_object = wasmer_wasi_generate_import_object_for_version(wasi_version, 0, 1, NULL, 0, NULL, 0, NULL, 0);  
  
// Instantiate a WebAssembly Instance from Wasm bytes and imports  
wasmer_instance_t *instance = NULL;  
// clock_gettime(CLOCK_REALTIME, &start);  
wasmer_result_t instantiate_result = wasmer_module_import_instantiate(&instance, module, import_object);  
  
if(instantiate_result != WASMER_OK)  
{  
    print_wasmer_error();  
    return -1;  
}  
wasmer_value_t arguments[] = {0};  
wasmer_value_t results[] = {0};  
// Call the `sum` function with the prepared arguments and the return value.  
wasmer_result_t call_result = wasmer_instance_call(instance, "_start", arguments, 0, results, 1);  
int response_value = results[0].value.I32;   
printf("%d\n", response_value);  
wasmer_instance_destroy(instance);  
return 0;  
}  

调用_start函数相当于运行整个wasm代码