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#include "listnav.h"
#include "util.h"
#include <string.h>
void
listnav_init(struct listnav *nav)
{
memset(nav, 0, sizeof(struct listnav));
}
void
listnav_update_bounds(struct listnav *nav, int min, int max)
{
ASSERT(max >= min);
nav->min = min;
nav->max = max;
listnav_update_wlen(nav, MIN(nav->wlen, nav->max - nav->min));
}
void
listnav_update_wlen(struct listnav *nav, int wlen)
{
ASSERT(wlen >= 0);
nav->wlen = MIN(wlen, nav->max - nav->min);
if (nav->wmin < nav->min)
nav->wmin = nav->min;
if (nav->wmin + nav->wlen > nav->max)
nav->wmin = nav->max - nav->wlen;
nav->wmax = nav->wmin + nav->wlen;
nav->sel = MAX(MIN(nav->sel, nav->wmax - 1), nav->wmin);
}
void
listnav_update_sel(struct listnav *nav, int sel)
{
nav->sel = MAX(MIN(sel, nav->max - 1), nav->min);
if (nav->sel >= nav->wmax) {
nav->wmax = nav->sel + 1;
nav->wmin = MAX(nav->min, nav->wmax - nav->wlen);
} else if (nav->sel < nav->wmin) {
nav->wmin = nav->sel;
nav->wmax = MIN(nav->wmin + nav->wlen, nav->max);
}
}
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