Rcpp:从 Rcpp 中的包调用 C 函数 [英] Rcpp: Call C function from a package within Rcpp

问题描述

我想用 Rcpp 编写一个 C++ 函数，该函数使用包 hypred 中的 C 函数，该包位于 CRAN 这里.

I would like to write a C++ function with Rcpp that uses a C function found in the package hypred, which is on CRAN here.

我阅读了在 Rcpp 中使用其他包中的 C 函数，但不明白这是否适用于我，如果适用，该怎么做.

I read using C function from other package in Rcpp, but don't understand if this applies for me and if it would apply, what to do.

所需的函数位于源文件 /src/hypredRoutines.c 中，名为 meiosisFUNAllChr.

The desired function is in the the source file /src/hypredRoutines.c and is called meiosisFUNAllChr.

到目前为止我根据这个 SO 问题做了什么这里 是:

What I so far did based on this SO question here is:

1. 我将函数 meiosisFUNAllChr 与其余代码分开，并将其放在一个名为 meiosisFUNAllChr.c 的新文件中.

2. 我创建了一个名为 meiosisFUNAllChr.h 的头文件，其中包含:

1. I separated the function meiosisFUNAllChr from the rest of the code and placed it in a new file called meiosisFUNAllChr.c.

2. I created a header file called meiosisFUNAllChr.h containing:

#ifndef MEIOSISFUNALLCHR_H
#define MEIOSISFUNALLCHR_H
void meiosisFUNallChr (...);
#endif 

编译它

Compiled it with

gcc -c -o meiosisFUNAllChr.o meiosisFUNAllChr.c

创建了一个虚拟的 c++ 函数

Created a dummy c++ function

#include <Rcpp.h>
using namespace Rcpp;

extern "C" {
 #include "meiosisFUNallChr.h"
}

// [[Rcpp::export]]
int timesTwo(int x) {
 return x * 2;
}

此时用sourceCpp编译是不行的.你能告诉我如何让它工作吗?

At this point, compiling with sourceCpp does not work. Can you show me how to get it working?

非常感谢！

编辑

使用 sourceCpp 编译给了我:

Compiling with sourceCpp gives me:

meiosisFUNallChr.h: file or directory not found

推荐答案

hypred 注册了它的两个函数，在 R 级别你可以这样弄一个你想要的:

hypred registers its two functions, at the R level you can get hold of the one you want like this:

xp <- getDLLRegisteredRoutines( getLoadedDLLs()[["hypred"]] )[[".C"]][["meiosisFUNallChr"]]$address

我相信你可以像这样在 C++ 中访问函数指针:

I believe you can then access the function pointer in C++ like this:

DL_FUNC meiosisFUNallChr = reinterpret_cast<DL_FUNC>( R_ExternalPtrAddr(xp) ) ;

但是您最好与软件包作者协商他​​们实施 这个方案 如果你能证明你真的需要直接调用 C 函数.

But you'd be better off negotiating with the package authors that they implement this scheme if you can make a case that you really need to be calling the C function directly.

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