在二郎山运行C code座 [英] Run C Code Block in Erlang
问题描述
如何从二郎运行C code座? (或呼叫的Erlang C函数?)
How to Run C Code Block from Erlang? ( Or Call a C function from erlang? )
推荐答案
这是创建驱动程序
首先,你需要创建的C / C ++文件来做到这一点。
Firstly you'll need to create the C/C++ files to do it.
他们将需要包括
#include "erl_driver.h"
#include "ei.h"
然后,你需要设置驱动器映射
Then you'll need to set up the driver mapping
/* mapping of the drivers functions */
static ErlDrvEntry driver_entry = {
NULL, /* init */
startup_function_name, /* startup */
shutdown_function_name, /* shutdown */
NULL, /* output */
NULL, /* ready_input */
NULL, /* ready_output */
driver_name, /* the name of the driver */
NULL, /* finish */
NULL, /* handle */
NULL, /* control */
NULL, /* timeout */
outputv_function_name, /* outputv */
NULL, /* ready_async */
NULL, /* flush */
NULL, /* call */
NULL, /* event */
ERL_DRV_EXTENDED_MARKER, /* ERL_DRV_EXTENDED_MARKER */
ERL_DRV_EXTENDED_MAJOR_VERSION, /* ERL_DRV_EXTENDED_MAJOR_VERSION */
ERL_DRV_EXTENDED_MAJOR_VERSION, /* ERL_DRV_EXTENDED_MINOR_VERSION */
ERL_DRV_FLAG_USE_PORT_LOCKING /* ERL_DRV_FLAGs */
};
DRIVER_INIT(driver_name){
return &driver_entry;
}
请注意:如果你想运行C ++ code而不是C的你需要
Note: if you are trying to run C++ code instead of C you'll need
extern "C" {
DRIVER_INIT(driver_name){
return &driver_entry;
}
}
和则需要施放任何文字字符串(字符*)
And you will need to cast any literal string with (char *)
然后,它是很好的定义将包含端口信息的结构
Then it's good to define a struct that'll contain the port information
typedef struct
{
ErlDrvPort port;
} port_data;
最后,你要设置的所有功能。
Lastly, you'll want to set up all the functions
static ErlDrvData startup_function_name(ErlDrvPort port, char *doc)
{
/* Plus any other start up methods you need */
port_data* d = (port_data*)driver_alloc(sizeof(port_data));
d->port = port;
return (ErlDrvData)d;
}
/* Plus any other shutdown methods you need */
static void shutdown_function_name(ErlDrvData handle)
{
driver_free((char*)handle);
}
static void outputv_function_name(ErlDrvData handle, ErlIOVec *ev)
{
port_data* d = (port_data*)handle;
char* inputstring = ev->binv[1]->orig_bytes;
ErlDrvTermData spec[] = {
ERL_DRV_ATOM, driver_mk_atom("ok"),
ERL_DRV_BUF2BINARY, inputstring, strlen(inputstring)
ERL_DRV_TUPLE, 2
};
driver_send_term(d->port,driver_caller(d->port),spec,sizeof(spec)/sizeof(spec[0]));
}
您会想编译这个C / C ++ code到一个共享对象,并与ERL接口链接它
You'll want to compile this C/C++ code into a shared object and link it with the erl interface
g++ -fpic -rdynamic -shared file_name -lerl_interface -lei
现在从二郎,你会想要做的几件事情:
你需要加载驱动程序
Now from erlang you'll want to do a couple things: You'll need to load the driver
erl_ddll:load_driver("./location/of/driver", driver_name).
然后你就会打开一个端口给司机
Then you'll open a port to the driver
Port = open_port({spawn, driver_name}, [binary]).
和最后你可以发送数据到端口
And lastly you can sent data to the port
port_command(Port, <<"String to Echo Back"),
receive
{ok, String} -> io:format("Received ~p back from the driver")
end.
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