Memory Alignment

Why Alignment?

• CPU accesses aligned data faster
• Misaligned may trap (SIGBUS)
• SIMD requires 16/32/64-byte alignment

The Alignment Formula

aligned = (addr + alignment - 1) & ~(alignment - 1);

// Example: align 0x1004 to 16 bytes
// (0x1004 + 15) & ~15
// = 0x1013 & 0xFFF0
// = 0x1010

aligned_alloc Strategy

1. Allocate extra: size + alignment + ptr_size
2. Find aligned address in that space
3. Store original pointer before it
4. Return aligned address

Freeing

void aligned_free(void *ptr) {
    void *original = ((void**)ptr)[-1];
    free(original);
}