/****************************************************************************
*
* Copyright (C) 2012 PX4 Development Team. All rights reserved.
* Author: @author Lorenz Meier <lm@inf.ethz.ch>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name PX4 nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
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****************************************************************************/
/**
* @file conversions.c
* Implementation of commonly used conversions.
*/
#include <nuttx/config.h>
#include <float.h>
#include "conversions.h"
#define air_gas_constant 8.31432f
#define air_density_sea_level 1.225f
#define absolute_null_kelvin 273.15f
int16_t
int16_t_from_bytes(uint8_t bytes[])
{
union {
uint8_t b[2];
int16_t w;
} u;
u.b[1] = bytes[0];
u.b[0] = bytes[1];
return u.w;
}
float get_air_density(float static_pressure, float temperature_celsius)
{
return static_pressure/(air_gas_constant * (temperature_celsius + absolute_null_kelvin));
}
