讓我們說,這是你希望在你的Ruby腳本利用圖書館,稱之爲my_c_lib.c
:
#include <stdlib.h>
double *my_function(double array[], int size)
{
int i = 0;
double *new_array = malloc(sizeof(double) * size);
for (i = 0; i < size; i++) {
new_array[i] = array[i] * 2;
}
return new_array;
}
你可以編譯它,像這樣:
$ gcc -Wall -c my_c_lib.c -o my_c_lib.o
$ gcc -shared -o my_c_lib.so my_c_lib.o
現在,它已經準備好(my_c_lib.rb
):
require 'ffi'
module MyModule
extend FFI::Library
# Assuming the library files are in the same directory as this script
ffi_lib "./my_c_lib.so"
attach_function :my_function, [:pointer, :int], :pointer
end
array = [4, 6, 4]
size = array.size
offset = 0
# Create the pointer to the array
pointer = FFI::MemoryPointer.new :double, size
# Fill the memory location with your data
pointer.put_array_of_double offset, array
# Call the function ... it returns an FFI::Pointer
result_pointer = MyModule.my_function(pointer, size)
# Get the array and put it in `result_array` for use
result_array = result_pointer.read_array_of_double(size)
# Print it out!
p result_array
這裏是結果運行該腳本的:
$ ruby my_c_lib.rb
[8.0, 12.0, 8.0]
內存管理筆記...從文檔https://github.com/ffi/ffi/wiki/Pointers:
的FFI :: MemoryPointer類分配具有自動垃圾回收作爲甜味劑本機內存。當MemoryPointer超出範圍時,內存將作爲垃圾收集過程的一部分釋放。
因此,您不應該直接致電pointer.free
。此外,只是爲了檢查是否有手動免費result_pointer
,我打印提取陣列後調用result_pointer.free
,得到了這樣的警告
warning: calling free on non allocated pointer #<FFI::Pointer address=0x007fd32b611ec0>
所以看起來你不必手動自由result_pointer
無論是。