ref: 094fc8b15f98807833143e29f1f7d36a1ca4b28c
dir: /sys/src/cmd/python/Python/memmove.c/
/* A perhaps slow but I hope correct implementation of memmove */ extern char *memcpy(char *, char *, int); char * memmove(char *dst, char *src, int n) { char *realdst = dst; if (n <= 0) return dst; if (src >= dst+n || dst >= src+n) return memcpy(dst, src, n); if (src > dst) { while (--n >= 0) *dst++ = *src++; } else if (src < dst) { src += n; dst += n; while (--n >= 0) *--dst = *--src; } return realdst; }