c - 使用 Fiddle 将 RUBY 数组传递给 C DLL

Question

首先，我知道我的问题与下面发布的问题类似。 How to deal with array pointers in ruby Fiddle

但这个问题确实没有答案。我的问题是用 ruby​​ 编写一个函数，它将接受一个 ruby​​ float 组作为输入并返回一个可以在 C DLL 中处理的 Fiddle::Pointer。这是它

# transform an ruby array of double to Fiddle::Pointer and processed as double* in C DLL
# @param [Array] array the ruby array, e.g. [1.0, 2.0, 3.0]
# @return [Fiddle::Pointer] fiddle pointer that could be processed as double * in C
def double_array_to_ptr(array)
  length = array.length
  ptr = Fiddle::Pointer.malloc(length * Fiddle::SIZEOF_DOUBLE)

  # initialize the ptr with numbers in array
  for i in 0..length-1
    # how to initialize the ptr
    # maybe ptr[start, length] would help, I have tried but no success

  end
  return ptr
end

C 函数可能看起来像这样

/**
 * \brief       H2OSetGlobalOffset set the global offset of data
 * \param[in]   H2OProjectH project project manager, this one has been initialized
 * \param[in]   double * offset offset data, the buffer is initilized in ruby 
*/
H2O_EXPORT void H2OSetGlobalOffset(H2OProjectH project, double* offset);

该函数已经用Fiddle::Importer 包装了，这与上一个问题相同。所以问题是如何在 ruby​​ 代码中初始化 Fiddle::Pointer。

谢谢!

Answer 1

arr = [1.0, 2.0, 3.0]
ptr = Fiddle::Pointer[arr.pack('E*')]

E* 是小端字节序，

从这个 Ruby forum link 得到以上内容

有关不同数据类型的打包和解包的更多信息 check this post