The CMSIS DSP 5 library
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functions/ControllerFunctions/arm_sin_cos_f32.c
- Committer:
- xorjoep
- Date:
- 2018-06-21
- Revision:
- 3:4098b9d3d571
- Parent:
- 1:24714b45cd1b
File content as of revision 3:4098b9d3d571:
/* ---------------------------------------------------------------------- * Project: CMSIS DSP Library * Title: arm_sin_cos_f32.c * Description: Sine and Cosine calculation for floating-point values * * $Date: 27. January 2017 * $Revision: V.1.5.1 * * Target Processor: Cortex-M cores * -------------------------------------------------------------------- */ /* * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved. * * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the License); you may * not use this file except in compliance with the License. * You may obtain a copy of the License at * * www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an AS IS BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include "arm_math.h" #include "arm_common_tables.h" /** * @ingroup groupController */ /** * @defgroup SinCos Sine Cosine * * Computes the trigonometric sine and cosine values using a combination of table lookup * and linear interpolation. * There are separate functions for Q31 and floating-point data types. * The input to the floating-point version is in degrees while the * fixed-point Q31 have a scaled input with the range * [-1 0.9999] mapping to [-180 +180] degrees. * * The floating point function also allows values that are out of the usual range. When this happens, the function will * take extra time to adjust the input value to the range of [-180 180]. * * The result is accurate to 5 digits after the decimal point. * * The implementation is based on table lookup using 360 values together with linear interpolation. * The steps used are: * -# Calculation of the nearest integer table index. * -# Compute the fractional portion (fract) of the input. * -# Fetch the value corresponding to \c index from sine table to \c y0 and also value from \c index+1 to \c y1. * -# Sine value is computed as <code> *psinVal = y0 + (fract * (y1 - y0))</code>. * -# Fetch the value corresponding to \c index from cosine table to \c y0 and also value from \c index+1 to \c y1. * -# Cosine value is computed as <code> *pcosVal = y0 + (fract * (y1 - y0))</code>. */ /** * @addtogroup SinCos * @{ */ /** * @brief Floating-point sin_cos function. * @param[in] theta input value in degrees * @param[out] *pSinVal points to the processed sine output. * @param[out] *pCosVal points to the processed cos output. * @return none. */ void arm_sin_cos_f32( float32_t theta, float32_t * pSinVal, float32_t * pCosVal) { float32_t fract, in; /* Temporary variables for input, output */ uint16_t indexS, indexC; /* Index variable */ float32_t f1, f2, d1, d2; /* Two nearest output values */ float32_t findex, Dn, Df, temp; /* input x is in degrees */ /* Scale the input, divide input by 360, for cosine add 0.25 (pi/2) to read sine table */ in = theta * 0.00277777777778f; if (in < 0.0f) { in = -in; } in = in - (int32_t)in; /* Calculation of index of the table */ findex = (float32_t) FAST_MATH_TABLE_SIZE * in; indexS = ((uint16_t)findex) & 0x1ff; indexC = (indexS + (FAST_MATH_TABLE_SIZE / 4)) & 0x1ff; /* fractional value calculation */ fract = findex - (float32_t) indexS; /* Read two nearest values of input value from the cos & sin tables */ f1 = sinTable_f32[indexC+0]; f2 = sinTable_f32[indexC+1]; d1 = -sinTable_f32[indexS+0]; d2 = -sinTable_f32[indexS+1]; temp = (1.0f - fract) * f1 + fract * f2; Dn = 0.0122718463030f; // delta between the two points (fixed), in this case 2*pi/FAST_MATH_TABLE_SIZE Df = f2 - f1; // delta between the values of the functions temp = Dn *(d1 + d2) - 2 * Df; temp = fract * temp + (3 * Df - (d2 + 2 * d1) * Dn); temp = fract * temp + d1 * Dn; /* Calculation of cosine value */ *pCosVal = fract * temp + f1; /* Read two nearest values of input value from the cos & sin tables */ f1 = sinTable_f32[indexS+0]; f2 = sinTable_f32[indexS+1]; d1 = sinTable_f32[indexC+0]; d2 = sinTable_f32[indexC+1]; temp = (1.0f - fract) * f1 + fract * f2; Df = f2 - f1; // delta between the values of the functions temp = Dn*(d1 + d2) - 2*Df; temp = fract*temp + (3*Df - (d2 + 2*d1)*Dn); temp = fract*temp + d1*Dn; /* Calculation of sine value */ *pSinVal = fract*temp + f1; if (theta < 0.0f) { *pSinVal = -*pSinVal; } } /** * @} end of SinCos group */