Cast a struct of ints to an array of ints

Question

I am using a library that has a function that takes an array of structs. That struct and function has the following layout:

struct TwoInt32s
{
  int32_t a;
         


        

Answer 1

You could allocate structures but treat their members as a sort of virtual array:

struct TwoInt32s *buffer = malloc(len * sizeof *buffer);

#define BUFFER(i) (*((i)%2 ? &buffer[(i)/2].b : &buffer[(i)/2].a))

/* fill in the buffer, e.g. */
for (int i = 0; i < len * 2; i++)
    BUFFER(i) = i;

Unfortunately, neither GCC nor Clang currently "get" this code.