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