gistfile3.txt

#!/usr/bin/env ruby

require 'rubygems'
require 'ffi'

module E
        extend FFI::Library
        ffi_lib 'libsample.dylib'

        class SampleStruct < FFI::Struct
                layout \
                        :i,     :int,
                        :tab,   [:int, 5]


        end
end

a = [1, 2, 3, 4, 5]

ptr_1 = FFI::MemoryPointer.new :pointer, E::SampleStruct.size
ptr_2 = FFI::MemoryPointer.new :pointer, E::SampleStruct.size

s1 = E::SampleStruct.new(ptr_1)
s2 = E::SampleStruct.new(ptr_2)

s1[:tab].to_ptr.write_array_of_int(a)
s2[:tab].to_ptr.write_array_of_int(a.reverse)

s1[:tab].to_ptr.read_array_of_int(5).each do |p|
        puts p
end

s2[:tab].to_ptr.read_array_of_int(5).each do |p|
        puts p
end

Makefile

CC=gcc
CFLAGS=-Wall -g -ansi -pedantic
OUT=sample

sample:
        $(CC) $(CFLAGS) -c sample.c
        $(CC) $(CFLAGS) -o $(OUT) sample.o

sample.o:
        $(CC) $(CFLAGS) -c sample.c -fPIC -o sample.o

libsample.dylib: sample.o
        $(CC) $(CFLAGS) -dynamiclib -shared -soname,[email protected] -o $@ sample.o 

lib: libsample.dylib

run:    sample
        ./sample

clean:
        rm -rf $(OUT) *.o *.dylib

sample.c

#include "sample.h"

/* this does nottin */

sample.h

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>

typedef struct {
        int i;
        int tab[5];
} SampleStruct;