/* ---------------------------------------------------------------------- * Project: CMSIS DSP Library * Title: arm_linear_interp_f16.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_f16.h" #if defined(ARM_FLOAT16_SUPPORTED) /** @ingroup groupInterpolation */ /** * @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. * */ float16_t arm_linear_interp_f16( const arm_linear_interp_instance_f16 * S, float16_t x) { float16_t y; float16_t x0, x1; /* Nearest input values */ float16_t y0, y1; /* Nearest output values */ float16_t xSpacing = S->xSpacing; /* spacing between input values */ int32_t i; /* Index variable */ const float16_t *pYData = S->pYData; /* pointer to output table */ /* Calculation of index */ i = (int32_t) (((_Float16)x - (_Float16)S->x1) / (_Float16)xSpacing); if (((_Float16)x < (_Float16)S->x1)) { /* 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 = (_Float16)S->x1 + (_Float16)i * (_Float16)xSpacing; x1 = (_Float16)S->x1 + (_Float16)(i + 1) * (_Float16)xSpacing; /* Read of nearest output values */ y0 = pYData[i]; y1 = pYData[i + 1]; /* Calculation of output */ y = (_Float16)y0 + ((_Float16)x - (_Float16)x0) * (((_Float16)y1 - (_Float16)y0) / ((_Float16)x1 - (_Float16)x0)); } /* returns output value */ return (y); } /** * @} end of LinearInterpolate group */ #endif /* #if defined(ARM_FLOAT16_SUPPORTED) */