C 8byte hello world

#include <unistd.h>

struct b5
{
    unsigned int i0 : 5;
    unsigned int i1 : 5;
    unsigned int i2 : 5;
    unsigned int i3 : 5;
    unsigned int i4 : 5;
    unsigned int i5 : 5;
} const stream[] = { {0x4, 0x1, 0x8, 0x8, 0xB, 0x14}, {0x13, 0xB, 0xE, 0x8, 0x0, 0x15} };

#define B5AT_1(o, index) (o.i##index)
#define B5AT_2(o, i, dex) dex == i ? B5AT_1(o, i) :
#define B5AT_3(o, i) B5AT_2(o, 0, i)B5AT_2(o, 1, i)B5AT_2(o, 2, i)B5AT_2(o, 3, i)B5AT_2(o, 4, i)B5AT_2(o, 5, i)0
#define B5AT(o, i) (B5AT_3(o, i))

unsigned char b5ToCh(const struct b5 arr, const unsigned char index)
{
    unsigned char ch = B5AT(arr, index);
    switch( ch )
    {
        case 0x14: return ' ';
        case 0x15: return '\n';
        default: return ch + 'd';
    }
    return '\0';
}

#undef B5AT
#undef B5AT_1
#undef B5AT_2
#undef B5AT_3

#define ARR_FOR(type, it, arr) for( type * it = arr ; it != arr + sizeof( arr ) / sizeof ( type ) ; it ++ )

int main() {
    char ch;
    ARR_FOR(struct b5, it, stream) for(int i = 0; i < 6; i++) ch = b5ToCh(*it, i), write(STDOUT_FILENO, &ch, 1);
    return 0;
}

#undef ARR_FOR