HISTCOUNTER
p->lowpc = rounddown(lowpc, HISTFRACTION * sizeof(HISTCOUNTER));
p->highpc = roundup(highpc, HISTFRACTION * sizeof(HISTCOUNTER));
HISTFRACTION * sizeof(HISTCOUNTER));
HISTFRACTION * sizeof(HISTCOUNTER));
#define MAXARCS ((1 << (unsigned int)(8 * sizeof(HISTCOUNTER))) - 2)