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Diffstat (limited to 'Drivers/CMSIS/DSP/Source/InterpolationFunctions/arm_linear_interp_f32.c')
| -rw-r--r-- | Drivers/CMSIS/DSP/Source/InterpolationFunctions/arm_linear_interp_f32.c | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/Drivers/CMSIS/DSP/Source/InterpolationFunctions/arm_linear_interp_f32.c b/Drivers/CMSIS/DSP/Source/InterpolationFunctions/arm_linear_interp_f32.c new file mode 100644 index 0000000..fc60bec --- /dev/null +++ b/Drivers/CMSIS/DSP/Source/InterpolationFunctions/arm_linear_interp_f32.c @@ -0,0 +1,125 @@ +/* ---------------------------------------------------------------------- + * Project: CMSIS DSP Library + * Title: arm_linear_interp_f32.c + * Description: Floating-point linear interpolation + * + * $Date: 23 April 2021 + * $Revision: V1.9.0 + * + * Target Processor: Cortex-M and Cortex-A cores + * -------------------------------------------------------------------- */ +/* + * Copyright (C) 2010-2021 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 "dsp/interpolation_functions.h" + +/** + @ingroup groupInterpolation + */ + +/** + * @defgroup LinearInterpolate Linear Interpolation + * + * Linear interpolation is a method of curve fitting using linear polynomials. + * Linear interpolation works by effectively drawing a straight line between two neighboring samples and returning the appropriate point along that line + * + * \par + * \image html LinearInterp.gif "Linear interpolation" + * + * \par + * A Linear Interpolate function calculates an output value(y), for the input(x) + * using linear interpolation of the input values x0, x1( nearest input values) and the output values y0 and y1(nearest output values) + * + * \par Algorithm: + * <pre> + * y = y0 + (x - x0) * ((y1 - y0)/(x1-x0)) + * where x0, x1 are nearest values of input x + * y0, y1 are nearest values to output y + * </pre> + * + * \par + * This set of functions implements Linear interpolation process + * for Q7, Q15, Q31, and floating-point data types. The functions operate on a single + * sample of data and each call to the function returns a single processed value. + * <code>S</code> points to an instance of the Linear Interpolate function data structure. + * <code>x</code> is the input sample value. The functions returns the output value. + * + * \par + * if x is outside of the table boundary, Linear interpolation returns first value of the table + * if x is below input range and returns last value of table if x is above range. + */ + +/** + * @addtogroup LinearInterpolate + * @{ + */ + + /** + * @brief Process function for the floating-point Linear Interpolation Function. + * @param[in,out] S is an instance of the floating-point Linear Interpolation structure + * @param[in] x input sample to process + * @return y processed output sample. + * + */ + float32_t arm_linear_interp_f32( + arm_linear_interp_instance_f32 * S, + float32_t x) + { + float32_t y; + float32_t x0, x1; /* Nearest input values */ + float32_t y0, y1; /* Nearest output values */ + float32_t xSpacing = S->xSpacing; /* spacing between input values */ + int32_t i; /* Index variable */ + float32_t *pYData = S->pYData; /* pointer to output table */ + + /* Calculation of index */ + i = (int32_t) ((x - S->x1) / xSpacing); + + if (i < 0) + { + /* Iniatilize output for below specified range as least output value of table */ + y = pYData[0]; + } + else if ((uint32_t)i >= (S->nValues - 1)) + { + /* Iniatilize output for above specified range as last output value of table */ + y = pYData[S->nValues - 1]; + } + else + { + /* Calculation of nearest input values */ + x0 = S->x1 + i * xSpacing; + x1 = S->x1 + (i + 1) * xSpacing; + + /* Read of nearest output values */ + y0 = pYData[i]; + y1 = pYData[i + 1]; + + /* Calculation of output */ + y = y0 + (x - x0) * ((y1 - y0) / (x1 - x0)); + + } + + /* returns output value */ + return (y); + } + + /** + * @} end of LinearInterpolate group + */ + |