void autoiso() {
ev_t limit;
ec_t ec = EC_ZERO;
ev_t ev = EV_ZERO;
iso_t newiso;
switch (DPData.ae) {
case AE_MODE_M:
if (DPData.tv_val != TV_VAL_BULB) {
// M mode: set ISO to match exposure
ec = - (status.measured_ec - persist.ev_comp);
// Normalize an apply new ISO
if (ec != EC_ZERO) {
if (settings.autoiso_relaxed)
ec = (ec - 1) / 3;
newiso = DPData.iso + ec;
newiso = CLAMP(newiso, settings.autoiso_miniso, settings.autoiso_maxiso);
newiso = EV_ROUND(newiso);
send_to_intercom(IC_SET_ISO, newiso);
}
}
return;
case AE_MODE_P:
case AE_MODE_AV:
// P / Av mode: raise ISO if shutter time is lower than limit
ev = status.measured_tv;
limit = settings.autoiso_mintv;
break;
case AE_MODE_TV:
// Tv mode: raise ISO if apperture is larger than lens' max plus offset
ev = status.measured_av;
limit = DPData.avo + settings.autoiso_maxav;
break;
default:
return;
}
// Decide whether we need to change current ISO
if (ev != EC_ZERO) {
if (ev < limit)
ec = (limit - ev) + EV_CODE(1, 0);
else if (ev >= limit + EV_CODE(1, 0))
ec = (limit - ev);
}
// Normalize an apply new ISO
if (ec != EC_ZERO) {
newiso = DPData.iso + ec;
newiso = CLAMP(newiso, settings.autoiso_miniso, settings.autoiso_maxiso);
newiso = EV_TRUNC(newiso);
send_to_intercom(IC_SET_ISO, newiso);
}
}
iso_t iso_roll(iso_t iso) {
int step = (1 << settings.digital_iso_step);
int mask = 0x100 - step;
iso = iso & mask;
iso = EV_CODE(EV_VAL(iso), (EV_SUB(iso) + step) % 8);
return MIN(iso, ISO_EXT);
}
void viewfinder_change_evc(ec_t ev_comp) {
persist.ev_comp = CLAMP(ev_comp, EV_CODE(-2, 0), EV_CODE(2,0));
enqueue_action(persist_write);
}
ev_t ev_time(int s) {
return EV_CODE(7, 0) - 8.0f * float_log(s) / float_log(2);
}
iso_t iso_prev(iso_t iso) {
iso = EV_CODE(EV_VAL(iso) - 1, 0);
return MAX(iso, ISO_MIN);
}
iso_t iso_next(iso_t iso) {
iso = EV_CODE(EV_VAL(iso) + 1, 0);
return MIN(iso, ISO_MAX);
}
