libowfat/byte/byte_copyr.c

#include "byte.h"

/* byte_copyr copies in[len-1] to out[len-1], in[len-2] to out[len-2],
 * ... and in[0] to out[0] */
void byte_copyr(void* out, size_t len, const void* in) {
  register char* s=(char*)out+len;
  register const char* t=in;
  register const char* u=t+len;
  for (;;) {
    if (t>=u) break; --u; --s; *s=*u;
    if (t>=u) break; --u; --s; *s=*u;
    if (t>=u) break; --u; --s; *s=*u;
    if (t>=u) break; --u; --s; *s=*u;
  }
}