memmove.c

#define SYSCLIB_DISABLE_BUILTINS
#include <sysclib.h>
#include <stdint.h>
 
#ifdef __GNUC__
typedef __attribute__((__may_alias__)) size_t WT;
#define WS (sizeof(WT))
#endif
 
void *memmove(void *dest, const void *src, size_t n)
{
    char *d = dest;
    const char *s = src;
 
    if (d==s) return d;
    // cppcheck-suppress signConversion
    if ((uintptr_t)s-(uintptr_t)d-n <= -2*n) return memcpy(d, s, n);
 
    if (d<s) {
#ifdef __GNUC__
        if ((uintptr_t)s % WS == (uintptr_t)d % WS) {
            while ((uintptr_t)d % WS) {
                if (!n--) return dest;
                *d++ = *s++;
            }
            for (; n>=WS; n-=WS, d+=WS, s+=WS) *(WT *)d = *(WT *)s;
        }
#endif
        for (; n; n--) *d++ = *s++;
    } else {
#ifdef __GNUC__
        if ((uintptr_t)s % WS == (uintptr_t)d % WS) {
            while ((uintptr_t)(d+n) % WS) {
                if (!n--) return dest;
                d[n] = s[n];
            }
            while (n>=WS) n-=WS, *(WT *)(d+n) = *(WT *)(s+n);
        }
#endif
        while (n) n--, d[n] = s[n];
    }
 
    return dest;
}