src/main/common/maths.h

   1 /*
   2  * This file is part of Cleanflight.
   3  *
   4  * Cleanflight is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * Cleanflight is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with Cleanflight.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #pragma once
  19
  20 #include <stdint.h>
  21 #include <stdbool.h>
  22
  23 #ifndef sq
  24 #define sq(x) ((x)*(x))
  25 #endif
  26
  27 // Undefine this for use libc sinf/cosf. Keep this defined to use fast sin/cos approximations
  28 #define FAST_MATH             // order 9 approximation
  29 //#define VERY_FAST_MATH      // order 7 approximation
  30
  31 // Use floating point M_PI instead explicitly.
  32 #define M_PIf       3.14159265358979323846f
  33 #define M_LN2f      0.69314718055994530942f
  34 #define M_Ef        2.71828182845904523536f
  35
  36 #define RAD    (M_PIf / 180.0f)
  37
  38 #define DEGREES_TO_CENTIDEGREES(angle) ((angle) * 100)
  39 #define CENTIDEGREES_TO_DEGREES(angle) ((angle) / 100)
  40
  41 #define CENTIDEGREES_TO_DECIDEGREES(angle) ((angle) / 10)
  42 #define DECIDEGREES_TO_CENTIDEGREES(angle) ((angle) * 10)
  43
  44 #define DEGREES_TO_DECIDEGREES(angle) ((angle) * 10)
  45 #define DECIDEGREES_TO_DEGREES(angle) ((angle) / 10)
  46
  47 #define DEGREES_PER_DEKADEGREE 10
  48 #define DEGREES_TO_DEKADEGREES(angle) ((angle) / DEGREES_PER_DEKADEGREE)
  49 #define DEKADEGREES_TO_DEGREES(angle) ((angle) * DEGREES_PER_DEKADEGREE)
  50
  51 #define DEGREES_TO_RADIANS(angle) ((angle) * RAD)
  52 #define RADIANS_TO_DEGREES(angle) ((angle) / RAD)
  53 #define DECIDEGREES_TO_RADIANS(angle) (((angle) / 10.0f) * RAD)
  54 #define RADIANS_TO_DECIDEGREES(angle) (((angle) * 10.0f) / RAD)
  55
  56 #define RADIANS_TO_CENTIDEGREES(angle) (((angle) * 100.0f) / RAD)
  57 #define CENTIDEGREES_TO_RADIANS(angle) (((angle) / 100.0f) * RAD)
  58
  59 #define CENTIMETERS_TO_CENTIFEET(cm)            (cm / 0.3048)
  60 #define CENTIMETERS_TO_FEET(cm)                 (cm / 30.48)
  61 #define CENTIMETERS_TO_METERS(cm)               (cm / 100)
  62
  63 #define METERS_TO_CENTIMETERS(m)                (m * 100)
  64
  65 #define CMSEC_TO_CENTIMPH(cms)      (cms * 2.2369363)
  66 #define CMSEC_TO_CENTIKPH(cms)      (cms * 3.6)
  67 #define CMSEC_TO_CENTIKNOTS(cms)    (cms * 1.943845)
  68
  69 #define C_TO_KELVIN(temp) (temp + 273.15f)
  70
  71 // Standard Sea Level values
  72 // Ref:https://en.wikipedia.org/wiki/Standard_sea_level
  73 #define SSL_AIR_DENSITY         1.225f // kg/m^3
  74 #define SSL_AIR_PRESSURE 101325.01576f // Pascal
  75 #define SSL_AIR_TEMPERATURE    288.15f // K
  76
  77 // copied from https://code.google.com/p/cxutil/source/browse/include/cxutil/utility.h#70
  78 #define _CHOOSE2(binoper, lexpr, lvar, rexpr, rvar)         \
  79     ( __extension__ ({                                      \
  80             __typeof__(lexpr) lvar = (lexpr);               \
  81             __typeof__(rexpr) rvar = (rexpr);               \
  82             lvar binoper rvar ? lvar : rvar;                \
  83         }))
  84 #define _CHOOSE_VAR2(prefix, unique) prefix##unique
  85 #define _CHOOSE_VAR(prefix, unique) _CHOOSE_VAR2(prefix, unique)
  86 #define _CHOOSE(binoper, lexpr, rexpr)                   \
  87     _CHOOSE2(                                            \
  88         binoper,                                         \
  89         lexpr, _CHOOSE_VAR(_left, __COUNTER__),          \
  90         rexpr, _CHOOSE_VAR(_right, __COUNTER__)          \
  91         )
  92 #define MIN(a, b) _CHOOSE(<, a, b)
  93 #define MAX(a, b) _CHOOSE(>, a, b)
  94
  95 #define _ABS_II(x, var)                           \
  96     ( __extension__ ({                            \
  97         __typeof__(x) var = (x);                  \
  98         var < 0 ? -var : var;                     \
  99     }))
 100 #define _ABS_I(x, var) _ABS_II(x, var)
 101 #define ABS(x) _ABS_I(x, _CHOOSE_VAR(_abs, __COUNTER__))
 102
 103 #define power3(x) ((x)*(x)*(x))
 104
 105 // Floating point Euler angles.
 106 typedef struct fp_angles {
 107     float roll;
 108     float pitch;
 109     float yaw;
 110 } fp_angles_def;
 111
 112 typedef union {
 113     float raw[3];
 114     fp_angles_def angles;
 115 } fp_angles_t;
 116
 117 typedef struct stdev_s
 118 {
 119     float m_oldM, m_newM, m_oldS, m_newS;
 120     int m_n;
 121 } stdev_t;
 122
 123 typedef struct filterWithBufferSample_s {
 124     float value;
 125     uint32_t timestamp;
 126 } filterWithBufferSample_t;
 127
 128 typedef struct filterWithBufferState_s {
 129     uint16_t filter_size;
 130     uint16_t sample_index;
 131     filterWithBufferSample_t * samples;
 132 } filterWithBufferState_t;
 133
 134 typedef struct {
 135     float XtY[4];
 136     float XtX[4][4];
 137 } sensorCalibrationState_t;
 138
 139 void sensorCalibrationResetState(sensorCalibrationState_t * state);
 140 void sensorCalibrationPushSampleForOffsetCalculation(sensorCalibrationState_t * state, int32_t sample[3]);
 141 void sensorCalibrationPushSampleForScaleCalculation(sensorCalibrationState_t * state, int axis, int32_t sample[3], int target);
 142 bool sensorCalibrationSolveForOffset(sensorCalibrationState_t * state, float result[3]);
 143 bool sensorCalibrationSolveForScale(sensorCalibrationState_t * state, float result[3]);
 144
 145 int gcd(int num, int denom);
 146 int32_t applyDeadband(int32_t value, int32_t deadband);
 147 int32_t applyDeadbandRescaled(int32_t value, int32_t deadband, int32_t min, int32_t max);
 148
 149 int32_t constrain(int32_t amt, int32_t low, int32_t high);
 150 float constrainf(float amt, float low, float high);
 151
 152 void devClear(stdev_t *dev);
 153 void devPush(stdev_t *dev, float x);
 154 float devVariance(stdev_t *dev);
 155 float devStandardDeviation(stdev_t *dev);
 156 float degreesToRadians(int16_t degrees);
 157
 158 int scaleRange(int x, int srcMin, int srcMax, int destMin, int destMax);
 159 float scaleRangef(float x, float srcMin, float srcMax, float destMin, float destMax);
 160
 161 int32_t wrap_18000(int32_t angle);
 162 int32_t wrap_36000(int32_t angle);
 163
 164 int32_t quickMedianFilter3(int32_t * v);
 165 int32_t quickMedianFilter5(int32_t * v);
 166 int32_t quickMedianFilter7(int32_t * v);
 167 int32_t quickMedianFilter9(int32_t * v);
 168
 169 int16_t quickMedianFilter3_16(int16_t * v);
 170 int16_t quickMedianFilter5_16(int16_t * v);
 171
 172 #if defined(FAST_MATH) || defined(VERY_FAST_MATH)
 173 float sin_approx(float x);
 174 float cos_approx(float x);
 175 float atan2_approx(float y, float x);
 176 float acos_approx(float x);
 177 #define tan_approx(x)       (sin_approx(x) / cos_approx(x))
 178 #define asin_approx(x)      (M_PIf / 2 - acos_approx(x))
 179 #else
 180 #define asin_approx(x)      asinf(x)
 181 #define sin_approx(x)       sinf(x)
 182 #define cos_approx(x)       cosf(x)
 183 #define atan2_approx(y,x)   atan2f(y,x)
 184 #define acos_approx(x)      acosf(x)
 185 #define tan_approx(x)       tanf(x)
 186 #endif
 187
 188 void arraySubInt32(int32_t *dest, int32_t *array1, int32_t *array2, int count);
 189
 190 float bellCurve(const float x, const float curveWidth);
 191 float fast_fsqrtf(const double value);
 192 float calc_length_pythagorean_2D(const float firstElement, const float secondElement);
 193 float calc_length_pythagorean_3D(const float firstElement, const float secondElement, const float thirdElement);