| 提交 | 用户 | age | ||
| bfc108 | 1 | /* ---------------------------------------------------------------------- |
| Q | 2 | * Copyright (C) 2010-2014 ARM Limited. All rights reserved. |
| 3 | * | |
| 4 | * $Date: 19. March 2015 | |
| 5 | * $Revision: V.1.4.5 | |
| 6 | * | |
| 7 | * Project: CMSIS DSP Library | |
| 8 | * Title: arm_sin_cos_f32.c | |
| 9 | * | |
| 10 | * Description: Sine and Cosine calculation for floating-point values. | |
| 11 | * | |
| 12 | * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 | |
| 13 | * | |
| 14 | * Redistribution and use in source and binary forms, with or without | |
| 15 | * modification, are permitted provided that the following conditions | |
| 16 | * are met: | |
| 17 | * - Redistributions of source code must retain the above copyright | |
| 18 | * notice, this list of conditions and the following disclaimer. | |
| 19 | * - Redistributions in binary form must reproduce the above copyright | |
| 20 | * notice, this list of conditions and the following disclaimer in | |
| 21 | * the documentation and/or other materials provided with the | |
| 22 | * distribution. | |
| 23 | * - Neither the name of ARM LIMITED nor the names of its contributors | |
| 24 | * may be used to endorse or promote products derived from this | |
| 25 | * software without specific prior written permission. | |
| 26 | * | |
| 27 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| 28 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| 29 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS | |
| 30 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE | |
| 31 | * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, | |
| 32 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, | |
| 33 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
| 34 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER | |
| 35 | * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
| 36 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN | |
| 37 | * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
| 38 | * POSSIBILITY OF SUCH DAMAGE. | |
| 39 | * -------------------------------------------------------------------- */ | |
| 40 | ||
| 41 | #include "arm_math.h" | |
| 42 | #include "arm_common_tables.h" | |
| 43 | ||
| 44 | /** | |
| 45 | * @ingroup groupController | |
| 46 | */ | |
| 47 | ||
| 48 | /** | |
| 49 | * @defgroup SinCos Sine Cosine | |
| 50 | * | |
| 51 | * Computes the trigonometric sine and cosine values using a combination of table lookup | |
| 52 | * and linear interpolation. | |
| 53 | * There are separate functions for Q31 and floating-point data types. | |
| 54 | * The input to the floating-point version is in degrees while the | |
| 55 | * fixed-point Q31 have a scaled input with the range | |
| 56 | * [-1 0.9999] mapping to [-180 +180] degrees. | |
| 57 | * | |
| 58 | * The floating point function also allows values that are out of the usual range. When this happens, the function will | |
| 59 | * take extra time to adjust the input value to the range of [-180 180]. | |
| 60 | * | |
| 61 | * The implementation is based on table lookup using 360 values together with linear interpolation. | |
| 62 | * The steps used are: | |
| 63 | * -# Calculation of the nearest integer table index. | |
| 64 | * -# Compute the fractional portion (fract) of the input. | |
| 65 | * -# Fetch the value corresponding to \c index from sine table to \c y0 and also value from \c index+1 to \c y1. | |
| 66 | * -# Sine value is computed as <code> *psinVal = y0 + (fract * (y1 - y0))</code>. | |
| 67 | * -# Fetch the value corresponding to \c index from cosine table to \c y0 and also value from \c index+1 to \c y1. | |
| 68 | * -# Cosine value is computed as <code> *pcosVal = y0 + (fract * (y1 - y0))</code>. | |
| 69 | */ | |
| 70 | ||
| 71 | /** | |
| 72 | * @addtogroup SinCos | |
| 73 | * @{ | |
| 74 | */ | |
| 75 | ||
| 76 | /** | |
| 77 | * @brief Floating-point sin_cos function. | |
| 78 | * @param[in] theta input value in degrees | |
| 79 | * @param[out] *pSinVal points to the processed sine output. | |
| 80 | * @param[out] *pCosVal points to the processed cos output. | |
| 81 | * @return none. | |
| 82 | */ | |
| 83 | ||
| 84 | void arm_sin_cos_f32( | |
| 85 | float32_t theta, | |
| 86 | float32_t * pSinVal, | |
| 87 | float32_t * pCosVal) | |
| 88 | { | |
| 89 | float32_t fract, in; /* Temporary variables for input, output */ | |
| 90 | uint16_t indexS, indexC; /* Index variable */ | |
| 91 | float32_t f1, f2, d1, d2; /* Two nearest output values */ | |
| 92 | int32_t n; | |
| 93 | float32_t findex, Dn, Df, temp; | |
| 94 | ||
| 95 | /* input x is in degrees */ | |
| 96 | /* Scale the input, divide input by 360, for cosine add 0.25 (pi/2) to read sine table */ | |
| 97 | in = theta * 0.00277777777778f; | |
| 98 | ||
| 99 | /* Calculation of floor value of input */ | |
| 100 | n = (int32_t) in; | |
| 101 | ||
| 102 | /* Make negative values towards -infinity */ | |
| 103 | if(in < 0.0f) | |
| 104 | { | |
| 105 | n--; | |
| 106 | } | |
| 107 | /* Map input value to [0 1] */ | |
| 108 | in = in - (float32_t) n; | |
| 109 | ||
| 110 | /* Calculation of index of the table */ | |
| 111 | findex = (float32_t) FAST_MATH_TABLE_SIZE * in; | |
| 112 | indexS = ((uint16_t)findex) & 0x1ff; | |
| 113 | indexC = (indexS + (FAST_MATH_TABLE_SIZE / 4)) & 0x1ff; | |
| 114 | ||
| 115 | /* fractional value calculation */ | |
| 116 | fract = findex - (float32_t) indexS; | |
| 117 | ||
| 118 | /* Read two nearest values of input value from the cos & sin tables */ | |
| 119 | f1 = sinTable_f32[indexC+0]; | |
| 120 | f2 = sinTable_f32[indexC+1]; | |
| 121 | d1 = -sinTable_f32[indexS+0]; | |
| 122 | d2 = -sinTable_f32[indexS+1]; | |
| 123 | ||
| 124 | Dn = 0.0122718463030f; // delta between the two points (fixed), in this case 2*pi/FAST_MATH_TABLE_SIZE | |
| 125 | Df = f2 - f1; // delta between the values of the functions | |
| 126 | temp = Dn*(d1 + d2) - 2*Df; | |
| 127 | temp = fract*temp + (3*Df - (d2 + 2*d1)*Dn); | |
| 128 | temp = fract*temp + d1*Dn; | |
| 129 | ||
| 130 | /* Calculation of cosine value */ | |
| 131 | *pCosVal = fract*temp + f1; | |
| 132 | ||
| 133 | /* Read two nearest values of input value from the cos & sin tables */ | |
| 134 | f1 = sinTable_f32[indexS+0]; | |
| 135 | f2 = sinTable_f32[indexS+1]; | |
| 136 | d1 = sinTable_f32[indexC+0]; | |
| 137 | d2 = sinTable_f32[indexC+1]; | |
| 138 | ||
| 139 | Df = f2 - f1; // delta between the values of the functions | |
| 140 | temp = Dn*(d1 + d2) - 2*Df; | |
| 141 | temp = fract*temp + (3*Df - (d2 + 2*d1)*Dn); | |
| 142 | temp = fract*temp + d1*Dn; | |
| 143 | ||
| 144 | /* Calculation of sine value */ | |
| 145 | *pSinVal = fract*temp + f1; | |
| 146 | } | |
| 147 | /** | |
| 148 | * @} end of SinCos group | |
| 149 | */ | |
