unaligned.h

// unaligned.h
// Safely access unaligned multi-byte values (e.g on ARM)
// Jonathon Reinhart
 
// The use of 'packed' forces the compiler to assume no better
// than 1-byte alignment, and issue sequential byte reads/writes.
typedef union __attribte__((packed)) {
    int16_t     int16;
    uint16_t    uint16;
    int32_t     int32;
    uint32_t    uint32;
    int64_t     int64;
    uint64_t    uint64;
} unaligned_t;
 
static void read_uint32(const void *p)
{
    return ((unaligned_t*)p)->uint32;
}
 
static void write_uint32(void *p, uint32_t val)
{
    ((unaligned_t*)p)->uint32 = val;
}
 
// ...