Rev 2248 | Details | Compare with Previous | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 2248 | - | 1 | /************************************************************************************************************************************** |
| 2 | * File: mymath.c |
||
| 3 | * |
||
| 4 | * Purpose: mathematic functions |
||
| 5 | * |
||
| 6 | * Functions: int16_t c_sin_8192(int16_t angle) |
||
| 7 | * int16_t c_cos_8192(int16_t angle) |
||
| 8 | * int16_t c_atan2(int16_t y, int16_t x) |
||
| 9 | * uint32_t c_sqrt(uint32_t a) |
||
| 10 | * |
||
| 11 | * hardware: Flight Ctrl V1.3 |
||
| 12 | * |
||
| 13 | * Created: Feb 2013 |
||
| 14 | * |
||
| 15 | *************************************************************************************************************************************/ |
||
| 16 | #include "mymath.h" |
||
| 17 | |||
| 18 | #include <stdlib.h> |
||
| 19 | #include <avr/pgmspace.h> |
||
| 20 | |||
| 21 | |||
| 22 | |||
| 23 | const uint16_t pgm_sinlookup[91] PROGMEM = {0, 143, 286, 429, 571, 714, 856, 998, 1140, 1282, 1423, 1563, 1703, 1843, 1982, 2120, 2258, 2395, 2531, 2667, 2802, 2936, 3069, 3201, 3332, 3462, 3591, 3719, 3846, 3972, 4096, 4219, 4341, 4462, 4581, 4699, 4815, 4930, 5043, 5155, 5266, 5374, 5482, 5587, 5691, 5793, 5893, 5991, 6088, 6183, 6275, 6366, 6455, 6542, 6627, 6710, 6791, 6870, 6947, 7022, 7094, 7165, 7233, 7299, 7363, 7424, 7484, 7541, 7595, 7648, 7698, 7746, 7791, 7834, 7875, 7913, 7949, 7982, 8013, 8041, 8068, 8091, 8112, 8131, 8147, 8161, 8172, 8181, 8187, 8191, 8192}; |
||
| 24 | |||
| 25 | //---------------------------------------------------------------------------------------------------------------------------------- |
||
| 26 | // Sinus with argument in degree at an angular resolution of 1 degree and a discretisation of 13 bit. |
||
| 27 | //---------------------------------------------------------------------------------------------------------------------------------- |
||
| 28 | int16_t c_sin_8192(int16_t angle) |
||
| 29 | { |
||
| 30 | int8_t m,n; |
||
| 31 | int16_t sinus; |
||
| 32 | |||
| 33 | // avoid negative angles |
||
| 34 | if (angle < 0) |
||
| 35 | { |
||
| 36 | m = -1; |
||
| 37 | angle = abs(angle); |
||
| 38 | } |
||
| 39 | else m = +1; |
||
| 40 | |||
| 41 | // fold angle to intervall 0 to 359 |
||
| 42 | angle %= 360; |
||
| 43 | |||
| 44 | // check quadrant |
||
| 45 | if (angle <= 90) n=1; // first quadrant |
||
| 46 | else if ((angle > 90) && (angle <= 180)) {angle = 180 - angle; n = 1;} // second quadrant |
||
| 47 | else if ((angle > 180) && (angle <= 270)) {angle = angle - 180; n = -1;} // third quadrant |
||
| 48 | else {angle = 360 - angle; n = -1;} //fourth quadrant |
||
| 49 | // get lookup value |
||
| 50 | sinus = pgm_read_word(&pgm_sinlookup[angle]); |
||
| 51 | // calculate sinus value |
||
| 52 | return (sinus * m * n); |
||
| 53 | } |
||
| 54 | // ---------------------------------------------------------------------------------------------------------------------------------- |
||
| 55 | |||
| 56 | |||
| 57 | //---------------------------------------------------------------------------------------------------------------------------------- |
||
| 58 | // Cosinus with argument in degree at an angular resolution of 1 degree and a discretisation of 13 bit. |
||
| 59 | //---------------------------------------------------------------------------------------------------------------------------------- |
||
| 60 | int16_t c_cos_8192(int16_t angle) |
||
| 61 | { |
||
| 62 | return (c_sin_8192(90 - angle)); |
||
| 63 | } |
||
| 64 | // ---------------------------------------------------------------------------------------------------------------------------------- |
||
| 65 | |||
| 66 | |||
| 67 | |||
| 68 | const uint8_t pgm_atanlookup[346] PROGMEM = {0,1,2,3,4,4,5,6,7,8,9,10,11,11,12,13,14,15,16,17,17,18,19,20,21,21,22,23,24,24,25,26,27,27,28,29,29,30,31,31,32,33,33,34,35,35,36,36,37,37,38,39,39,40,40,41,41,42,42,43,43,44,44,45,45,45,46,46,47,47,48,48,48,49,49,50,50,50,51,51,51,52,52,52,53,53,53,54,54,54,55,55,55,55,56,56,56,57,57,57,57,58,58,58,58,59,59,59,59,60,60,60,60,60,61,61,61,61,62,62,62,62,62,63,63,63,63,63,63,64,64,64,64,64,64,65,65,65,65,65,65,66,66,66,66,66,66,66,67,67,67,67,67,67,67,68,68,68,68,68,68,68,68,69,69,69,69,69,69,69,69,69,70,70,70,70,70,70,70,70,70,71,71,71,71,71,71,71,71,71,71,71,72,72,72,72,72,72,72,72,72,72,72,73,73,73,73,73,73,73,73,73,73,73,73,73,73,74,74,74,74,74,74,74,74,74,74,74,74,74,74,75,75,75,75,75,75,75,75,75,75,75,75,75,75,75,75,75,76,76,76,76,76,76,76,76,76,76,76,76,76,76,76,76,76,76,76,77,77,77,77,77,77,77,77,77,77,77,77,77,77,77,77,77,77,77,77,77,77,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79,79}; |
||
| 69 | |||
| 70 | //---------------------------------------------------------------------------------------------------------------------------------- |
||
| 71 | // arcustangens returns degree in a range of +/. 180 deg |
||
| 72 | //---------------------------------------------------------------------------------------------------------------------------------- |
||
| 73 | int16_t c_atan2(int16_t y, int16_t x) |
||
| 74 | { |
||
| 75 | int16_t index, angle; |
||
| 76 | int8_t m; |
||
| 77 | |||
| 78 | if (!x && !y) return 0; //atan2(0, 0) is undefined |
||
| 79 | |||
| 80 | if (y < 0) m = -1; |
||
| 81 | else m = 1; |
||
| 82 | |||
| 83 | if (!x) return (90 * m); // atan2(y,0) = +/- 90 deg |
||
| 84 | |||
| 85 | index = (int16_t)(((int32_t)y * 64) / x);// calculate index for lookup table |
||
| 86 | if (index < 0) index = -index; |
||
| 87 | |||
| 88 | if (index < 346) angle = pgm_read_byte(&pgm_atanlookup[index]); // lookup for 0 deg to 79 deg |
||
| 89 | else if (index > 7334) angle = 90; // limit is 90 deg |
||
| 90 | else if (index > 2444) angle = 89; // 89 deg to 80 deg is mapped via intervalls |
||
| 91 | else if (index > 1465) angle = 88; |
||
| 92 | else if (index > 1046) angle = 87; |
||
| 93 | else if (index > 813) angle = 86; |
||
| 94 | else if (index > 664) angle = 85; |
||
| 95 | else if (index > 561) angle = 84; |
||
| 96 | else if (index > 486) angle = 83; |
||
| 97 | else if (index > 428) angle = 82; |
||
| 98 | else if (index > 382) angle = 81; |
||
| 99 | else angle = 80; // (index>345) |
||
| 100 | |||
| 101 | if (x > 0) return (angle * m); // 1st and 4th quadrant |
||
| 102 | else if ((x < 0) && (m > 0)) return (180 - angle); // 2nd quadrant |
||
| 103 | else return (angle - 180); // ( (x < 0) && (y < 0)) 3rd quadrant |
||
| 104 | } |
||
| 105 | // ---------------------------------------------------------------------------------------------------------------------------------- |
||
| 106 | |||
| 107 | |||
| 108 | //---------------------------------------------------------------------------------------------------------------------------------- |
||
| 109 | // Integer square root |
||
| 110 | //---------------------------------------------------------------------------------------------------------------------------------- |
||
| 111 | uint32_t c_sqrt(uint32_t a) |
||
| 112 | { |
||
| 113 | uint32_t rem = 0; |
||
| 114 | uint32_t root = 0; |
||
| 115 | uint8_t i; |
||
| 116 | |||
| 117 | for(i = 0; i < 16; i++) |
||
| 118 | { |
||
| 119 | root <<= 1; |
||
| 120 | rem = ((rem << 2) + (a >> 30)); |
||
| 121 | a <<= 2; |
||
| 122 | root++; |
||
| 123 | if(root <= rem) |
||
| 124 | { |
||
| 125 | rem -= root; |
||
| 126 | root++; |
||
| 127 | } |
||
| 128 | else root--; |
||
| 129 | } |
||
| 130 | return (root >> 1); |
||
| 131 | } |
||
| 132 | // ---------------------------------------------------------------------------------------------------------------------------------- |
||
| 133 | |||
| 134 | // *** EOF: ************************************************************************************************************************ |