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/*
* Copyright © 2012 Keith Packard <keithp@keithp.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*/
#include <ao.h>
/*
* The provided 'calibration' value is
* that needed to tune the radio to precisely 434550kHz.
* The relation between value and freq is linear, so
* to get the value for an arbitrary frequency:
*
* target_value target_freq
* ------------ = ------------
* cal_value cal_freq
*
* cal_value * target_freq
* target_value = -----------------------
* cal_freq
*/
int32_t ao_freq_to_set(int32_t target_freq, int32_t cal_value)
{
int64_t prod = (int64_t) target_freq * (int64_t) cal_value;
/* Round to nearest */
int32_t target_value = (prod + (434550 / 2)) / 434550;
return target_value;
}
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