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118 lines
3.2 KiB
C
118 lines
3.2 KiB
C
/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_bilinear_interp_f16.c
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* Description: Floating-point bilinear interpolation
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*
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* $Date: 23 April 2021
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* $Revision: V1.9.0
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*
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* Target Processor: Cortex-M and Cortex-A cores
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* -------------------------------------------------------------------- */
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/*
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* Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the License); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an AS IS BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "dsp/interpolation_functions_f16.h"
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#if defined(ARM_FLOAT16_SUPPORTED)
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/**
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@ingroup groupInterpolation
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*/
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/**
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* @addtogroup BilinearInterpolate
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* @{
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*/
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/**
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* @brief Floating-point bilinear interpolation.
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* @param[in,out] S points to an instance of the interpolation structure.
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* @param[in] X interpolation coordinate.
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* @param[in] Y interpolation coordinate.
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* @return out interpolated value.
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*/
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float16_t arm_bilinear_interp_f16(
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const arm_bilinear_interp_instance_f16 * S,
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float16_t X,
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float16_t Y)
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{
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float16_t out;
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float16_t f00, f01, f10, f11;
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const float16_t *pData = S->pData;
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int32_t xIndex, yIndex, index;
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float16_t xdiff, ydiff;
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float16_t b1, b2, b3, b4;
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xIndex = (int32_t) X;
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yIndex = (int32_t) Y;
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/* Care taken for table outside boundary */
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/* Returns zero output when values are outside table boundary */
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if (xIndex < 0 || xIndex > (S->numCols - 2) || yIndex < 0 || yIndex > (S->numRows - 2))
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{
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return (0);
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}
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/* Calculation of index for two nearest points in X-direction */
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index = (xIndex ) + (yIndex ) * S->numCols;
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/* Read two nearest points in X-direction */
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f00 = pData[index];
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f01 = pData[index + 1];
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/* Calculation of index for two nearest points in Y-direction */
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index = (xIndex ) + (yIndex+1) * S->numCols;
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/* Read two nearest points in Y-direction */
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f10 = pData[index];
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f11 = pData[index + 1];
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/* Calculation of intermediate values */
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b1 = f00;
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b2 = (_Float16)f01 - (_Float16)f00;
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b3 = (_Float16)f10 - (_Float16)f00;
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b4 = (_Float16)f00 - (_Float16)f01 - (_Float16)f10 + (_Float16)f11;
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/* Calculation of fractional part in X */
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xdiff = (_Float16)X - (_Float16)xIndex;
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/* Calculation of fractional part in Y */
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ydiff = (_Float16)Y - (_Float16)yIndex;
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/* Calculation of bi-linear interpolated output */
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out = (_Float16)b1 + (_Float16)b2 * (_Float16)xdiff +
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(_Float16)b3 * (_Float16)ydiff + (_Float16)b4 * (_Float16)xdiff * (_Float16)ydiff;
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/* return to application */
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return (out);
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}
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/**
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* @} end of BilinearInterpolate group
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*/
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#endif /* #if defined(ARM_FLOAT16_SUPPORTED) */
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