lib/main/CMSIS/DSP/Source/ControllerFunctions/arm_sin_cos_f32.c

   1 /* ----------------------------------------------------------------------
   2  * Project:      CMSIS DSP Library
   3  * Title:        arm_sin_cos_f32.c
   4  * Description:  Sine and Cosine calculation for floating-point values
   5  *
   6  * $Date:        27. January 2017
   7  * $Revision:    V.1.5.1
   8  *
   9  * Target Processor: Cortex-M cores
  10  * -------------------------------------------------------------------- */
  11 /*
  12  * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
  13  *
  14  * SPDX-License-Identifier: Apache-2.0
  15  *
  16  * Licensed under the Apache License, Version 2.0 (the License); you may
  17  * not use this file except in compliance with the License.
  18  * You may obtain a copy of the License at
  19  *
  20  * www.apache.org/licenses/LICENSE-2.0
  21  *
  22  * Unless required by applicable law or agreed to in writing, software
  23  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
  24  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  25  * See the License for the specific language governing permissions and
  26  * limitations under the License.
  27  */
  28
  29 #include "arm_math.h"
  30 #include "arm_common_tables.h"
  31
  32 /**
  33  * @ingroup groupController
  34  */
  35
  36 /**
  37  * @defgroup SinCos Sine Cosine
  38  *
  39  * Computes the trigonometric sine and cosine values using a combination of table lookup
  40  * and linear interpolation.
  41  * There are separate functions for Q31 and floating-point data types.
  42  * The input to the floating-point version is in degrees while the
  43  * fixed-point Q31 have a scaled input with the range
  44  * [-1 0.9999] mapping to [-180 +180] degrees.
  45  *
  46  * The floating point function also allows values that are out of the usual range. When this happens, the function will
  47  * take extra time to adjust the input value to the range of [-180 180].
  48  *
  49  * The result is accurate to 5 digits after the decimal point.
  50  *
  51  * The implementation is based on table lookup using 360 values together with linear interpolation.
  52  * The steps used are:
  53  *  -# Calculation of the nearest integer table index.
  54  *  -# Compute the fractional portion (fract) of the input.
  55  *  -# Fetch the value corresponding to \c index from sine table to \c y0 and also value from \c index+1 to \c y1.
  56  *  -# Sine value is computed as <code> *psinVal = y0 + (fract * (y1 - y0))</code>.
  57  *  -# Fetch the value corresponding to \c index from cosine table to \c y0 and also value from \c index+1 to \c y1.
  58  *  -# Cosine value is computed as <code> *pcosVal = y0 + (fract * (y1 - y0))</code>.
  59  */
  60
  61  /**
  62  * @addtogroup SinCos
  63  * @{
  64  */
  65
  66 /**
  67  * @brief  Floating-point sin_cos function.
  68  * @param[in]  theta    input value in degrees
  69  * @param[out] *pSinVal points to the processed sine output.
  70  * @param[out] *pCosVal points to the processed cos output.
  71  * @return none.
  72  */
  73
  74 void arm_sin_cos_f32(
  75                       float32_t theta,
  76                       float32_t * pSinVal,
  77                       float32_t * pCosVal)
  78 {
  79     float32_t fract, in;                             /* Temporary variables for input, output */
  80     uint16_t indexS, indexC;                         /* Index variable */
  81     float32_t f1, f2, d1, d2;                        /* Two nearest output values */
  82     float32_t findex, Dn, Df, temp;
  83
  84     /* input x is in degrees */
  85     /* Scale the input, divide input by 360, for cosine add 0.25 (pi/2) to read sine table */
  86     in = theta * 0.00277777777778f;
  87
  88     if (in < 0.0f)
  89     {
  90         in = -in;
  91     }
  92
  93     in = in - (int32_t)in;
  94
  95     /* Calculation of index of the table */
  96     findex = (float32_t) FAST_MATH_TABLE_SIZE * in;
  97     indexS = ((uint16_t)findex) & 0x1ff;
  98     indexC = (indexS + (FAST_MATH_TABLE_SIZE / 4)) & 0x1ff;
  99
 100     /* fractional value calculation */
 101     fract = findex - (float32_t) indexS;
 102
 103     /* Read two nearest values of input value from the cos & sin tables */
 104     f1 = sinTable_f32[indexC+0];
 105     f2 = sinTable_f32[indexC+1];
 106     d1 = -sinTable_f32[indexS+0];
 107     d2 = -sinTable_f32[indexS+1];
 108
 109     temp = (1.0f - fract) * f1 + fract * f2;
 110
 111     Dn = 0.0122718463030f; // delta between the two points (fixed), in this case 2*pi/FAST_MATH_TABLE_SIZE
 112     Df = f2 - f1;          // delta between the values of the functions
 113
 114     temp = Dn *(d1 + d2) - 2 * Df;
 115     temp = fract * temp + (3 * Df - (d2 + 2 * d1) * Dn);
 116     temp = fract * temp + d1 * Dn;
 117
 118     /* Calculation of cosine value */
 119     *pCosVal = fract * temp + f1;
 120
 121     /* Read two nearest values of input value from the cos & sin tables */
 122     f1 = sinTable_f32[indexS+0];
 123     f2 = sinTable_f32[indexS+1];
 124     d1 = sinTable_f32[indexC+0];
 125     d2 = sinTable_f32[indexC+1];
 126
 127     temp = (1.0f - fract) * f1 + fract * f2;
 128
 129     Df = f2 - f1; // delta between the values of the functions
 130     temp = Dn*(d1 + d2) - 2*Df;
 131     temp = fract*temp + (3*Df - (d2 + 2*d1)*Dn);
 132     temp = fract*temp + d1*Dn;
 133
 134     /* Calculation of sine value */
 135     *pSinVal = fract*temp + f1;
 136
 137     if (theta < 0.0f)
 138     {
 139         *pSinVal = -*pSinVal;
 140     }
 141 }
 142 /**
 143  * @} end of SinCos group
 144  */