Re: [RFC, 2.6] a simple FIFO implementation

[Peter Chubb]

>>>>> "Andrew" == Andrew Morton <akpm@xxxxxxxx> writes:


Andrew> All the struct needs is `head', `tail' and
Andrew> `number_of_bytes_at_buf', all unsigned.

Andrew> add(char c) {
Andrew>       p-> buf[p->head++ % p->number_of_bytes_at_buf] = c;
Andrew> }

This depends on how expensive % is.  On IA64, something like this:

     add(char c) {
	     int i = p->head == p->len ? p->head++ : 0;
	     p->buf[i] = c;
     }

is cheaper, as % generates a subroutine call to __modsi3.  It also is
shorter =-- 12 bundles as opposed to 15.
     


-- 
Dr Peter Chubb  http://www.gelato.unsw.edu.au  peterc AT gelato.unsw.edu.au
The technical we do immediately,  the political takes *forever*
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