CYAPA_BUFSIZE
#define CYAPA_BUFMASK (CYAPA_BUFSIZE - 1)
char buf[CYAPA_BUFSIZE];
n = CYAPA_BUFSIZE - (fifo->rindex & CYAPA_BUFMASK);
if (n > (CYAPA_BUFSIZE - (fifo->rindex & CYAPA_BUFMASK))) {
if (fifo->windex - fifo->rindex < CYAPA_BUFSIZE) {
n = CYAPA_BUFSIZE - (fifo->windex & CYAPA_BUFMASK);
if (n > (size_t)(CYAPA_BUFSIZE - (fifo->windex - fifo->rindex)))
n = (size_t)(CYAPA_BUFSIZE - (fifo->windex - fifo->rindex));