- char *from = afrom, *to = ato;
-
- if (size <= 0 || from == to)
- return;
-
- /* If the source and destination don't overlap, then bcopy can
- handle it. If they do overlap, but the destination is lower in
- memory than the source, we'll assume bcopy can handle that. */
- if (to < from || from + size <= to)
- bcopy (from, to, size);
-
- /* Otherwise, we'll copy from the end. */
- else
- {
- register char *endf = from + size;
- register char *endt = to + size;
-
- /* If TO - FROM is large, then we should break the copy into
- nonoverlapping chunks of TO - FROM bytes each. However, if
- TO - FROM is small, then the bcopy function call overhead
- makes this not worth it. The crossover point could be about
- anywhere. Since I don't think the obvious copy loop is too
- bad, I'm trying to err in its favor. */
- if (to - from < 64)
- {
- do
- *--endt = *--endf;
- while (endf != from);
- }
- else
- {
- for (;;)
- {
- endt -= (to - from);
- endf -= (to - from);
-
- if (endt < to)
- break;
-
- bcopy (endf, endt, to - from);
- }