-
-
-
-Build WAMR Core
-=========================
-Please follow below instructions to build WAMR core on different platforms.
-
-Linux
--------------------------
-Firstly please install library dependencies of lib gcc.
-Use below installation commands for Ubuntu Linux:
-``` Bash
-sudo apt install lib32gcc-5-dev
-sudo apt-get install g++-multilib
-```
-After installing dependencies, build the source code:
-``` Bash
-cd products/linux/
-mkdir build
-cd build
-cmake ..
-make
-```
-Zephyr
--------------------------
-You need download Zephyr source code first and embeded WAMR into it.
-``` Bash
-git clone https://github.com/zephyrproject-rtos/zephyr.git
-cd zephyr/samples/
-cp -a 
-
-
-A typical WAMR APIs usage is as below:
-``` C
- wasm_module_t module;
- wasm_module_inst_t inst;
- wasm_function_inst_t func;
- wasm_exec_env_t env;
- wasm_runtime_init();
- module = wasm_runtime_load(buffer, size, err, err_size);
- inst = wasm_runtime_instantiate(module, 0, err, err_size);
- func = wasm_runtime_lookup_function(inst, "fib", "(i32i32");
- env = wasm_runtime_create_exec_env(stack_size);
-
- if (!wasm_runtime_call_wasm(inst, env, func, 1, argv_buf) ) {
- wasm_runtime_clear_exception(inst);
- }
-
- wasm_runtime_destory_exec_env(env);
- wasm_runtime_deinstantiate(inst);
- wasm_runtime_unload(module);
- wasm_runtime_destroy();
-```
-
-
-WASM application library
-========================
-In general, there are 3 kinds of APIs for programming the WASM application:
-- Built-in APIs: WAMR has already provided a minimal API set for developers.
-- 3rd party APIs: Programmer can download include any 3rd party C source code, and added into their own WASM app source tree.
-- Platform native APIs: The board vendors define these APIs during their making board firmware. They are provided WASM application to invoke like built-in and 3rd party APIs. In this way board vendors extend APIs which can make programmers develop more complicated WASM apps.
-
-
-Built-in application library
----------------
-Built-in APIs include Libc APIs, Base library, Extension library reference.
-
-**Libc APIs**-It is the minimal Libc APIs like memory allocation and string copy etc. -The header files is ```lib/app-libs/libc/lib-base.h```. The API set is listed as below: -``` C -void *malloc(size_t size); -void *calloc(size_t n, size_t size); -void free(void *ptr); -int memcmp(const void *s1, const void *s2, size_t n); -void *memcpy(void *dest, const void *src, size_t n); -void *memmove(void *dest, const void *src, size_t n); -void *memset(void *s, int c, size_t n); -int putchar(int c); -int snprintf(char *str, size_t size, const char *format, ...); -int sprintf(char *str, const char *format, ...); -char *strchr(const char *s, int c); -int strcmp(const char *s1, const char *s2); -char *strcpy(char *dest, const char *src); -size_t strlen(const char *s); -int strncmp(const char * str1, const char * str2, size_t n); -char *strncpy(char *dest, const char *src, unsigned long n); -``` - -**Base library**
-The basic support like communication, timers etc is already available. The header files is ```lib/app-libs/base/wasm-app.h```, it includes request and response APIs, event pub/sub APIs and timer APIs. Please be noted that they may not work if you have no corresponding framework to work with them. -The API set is listed as below: -``` C -typedef void(*request_handler_f)(request_t *) ; -typedef void(*response_handler_f)(response_t *, void *) ; - -// Request APIs -bool api_register_resource_handler(const char *url, request_handler_f); -void api_send_request(request_t * request, response_handler_f response_handler, void * user_data); -void api_response_send(response_t *response); - -// event AP -bool api_publish_event(const char *url, int fmt, void *payload, int payload_len); -bool api_subscribe_event(const char * url, request_handler_f handler); - -struct user_timer; -typedef struct user_timer * user_timer_t; - -// Timer APIs -user_timer_t api_timer_create(int interval, bool is_period, bool auto_start, void(*on_user_timer_update)(user_timer_t -)); -void api_timer_cancel(user_timer_t timer); -void api_timer_restart(user_timer_t timer, int interval); -``` - -**Library extension reference**
-Currently we provide the sensor APIs as one library extension sample. The header file ```lib/app-libs/extension/sensor/sensor.h```, the API set is listed as below: -``` C -sensor_t sensor_open(const char* name, int index, - void(*on_sensor_event)(sensor_t, attr_container_t *, void *), - void *user_data); -bool sensor_config(sensor_t sensor, int interval, int bit_cfg, int delay); -bool sensor_config_with_attr_container(sensor_t sensor, attr_container_t *cfg); -bool sensor_close(sensor_t sensor); -``` - -The mechanism of exporting Native API to WASM application -======================================================= - -The basic working flow for WASM application calling into the native API is described as following diagram. -
-
-
-WAMR provides the macro `EXPORT_WASM_API` to enable users to export native API to WASM application. WAMR implemented a base API for timer and messaging by using `EXPORT_WASM_API`. They can be reference point of extending your own library.
-``` C
-static NativeSymbol extended_native_symbol_defs[] = {
- EXPORT_WASM_API(wasm_register_resource),
- EXPORT_WASM_API(wasm_response_send),
- EXPORT_WASM_API(wasm_post_request),
- EXPORT_WASM_API(wasm_sub_event),
- EXPORT_WASM_API(wasm_create_timer),
- EXPORT_WASM_API(wasm_timer_set_interval),
- EXPORT_WASM_API(wasm_timer_cancel),
- EXPORT_WASM_API(wasm_timer_restart)
-};
-```
-
-
- **Security attention:** The WebAssembly application is supposed to access its own memory space, the integrator should carefully design the native function to ensure the memory safe. The native API to be exporte to WASM application must follow the rules:
-- Only use 32 bits number for parameters
-- Don’t passing data structure pointer (do data serialization instead)
-- Do the pointer address conversion in native API
-- Don’t passing function pointer as callback
-
-Below is a sample of library extension. All invoke across WASM world and native world must be serialized and de-serialized, and native world must do boundary check for every incoming address from WASM world.
-
-
-
-Exporting native API steps
-==========================
-
-WAMR implemented a framework for developers to export APIs. The procedure to expose the platform APIs in three steps:
-
-**Step 1. Create a header file**-Declare the APIs for WASM application source project to include. - -**Step 2. Create a source file**
-Export the platform APIs, for example in ``` products/linux/ext-lib-export.c ``` -``` C -#include "lib-export.h" - -static NativeSymbol extended_native_symbol_defs[] = -{ -}; - -#include "ext-lib-export.h" -``` - -**Step 3. Register new APIs**
-Use macro EXPORT_WASM_API and EXPORT_WASM_API2 to add exported APIs into the array of ```extended_native_symbol_defs```. -The pre-defined MACRO `EXPORT_WASM_API` should be used to declare a function export: -``` c -#define EXPORT_WASM_API(symbol) {#symbol, symbol} -``` - -Below code example shows how to extend the library to support `customeized()`: -``` C -//lib-export-impl.c -void customized() -{ - // your code -} - - -// lib-export-dec.h -#ifndef _LIB_EXPORT_DEC_H_ -#define _LIB_EXPORT_DEC_H_ -#ifdef __cplusplus -extern "C" { -#endif - -void customized(); - -#ifdef __cplusplus -} -#endif -#endif - - -// ext-lib-export.c -#include "lib-export.h" -#include "lib-export-dec.h" - -static NativeSymbol extended_native_symbol_defs[] = -{ - EXPORT_WASM_API(customized) -}; - -#include "ext-lib-export.h" -``` -Use extended library ------------------------- -In the application source project, it includes the WAMR built-in APIs header file and platform extension header files. -Assume the board vendor extend the library which added a API called customized(). The WASM application would be like this: -``` C -#include