113 lines
3.4 KiB
C
113 lines
3.4 KiB
C
/**
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*******************************************************************************
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* @file OpenPDMFilter.h
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* @author CL
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* @version V1.0.0
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* @date 9-September-2015
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* @brief Header file for Open PDM audio software decoding Library.
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* This Library is used to decode and reconstruct the audio signal
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* produced by ST MEMS microphone (MP45Dxxx, MP34Dxxx).
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*******************************************************************************
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* @attention
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*
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* <h2><center>© COPYRIGHT 2018 STMicroelectronics</center></h2>
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may 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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* http://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,
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* WITHOUT 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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*/
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/* Define to prevent recursive inclusion -------------------------------------*/
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#ifndef __OPENPDMFILTER_H
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#define __OPENPDMFILTER_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Includes ------------------------------------------------------------------*/
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#include <stdint.h>
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/* Definitions ---------------------------------------------------------------*/
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/*
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* Enable to use a Look-Up Table to improve performances while using more FLASH
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* and RAM memory.
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* Note: Without Look-Up Table up to stereo@16KHz configuration is supported.
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*/
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#define USE_LUT
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#define SINCN 3
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#define DECIMATION_MAX 128 // can be 128 but this didn't work for me
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#define FILTER_GAIN 16
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#define HTONS(A) ((((uint16_t)(A) & 0xff00) >> 8) | \
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(((uint16_t)(A) & 0x00ff) << 8))
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#define RoundDiv(a, b) (((a) > 0) ? (((a) + (b) / 2) / (b)) : (((a) - (b) / 2) / (b)))
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#define SaturaLH(N, L, H) (((N) < (L)) ? (L) : (((N) > (H)) ? (H) : (N)))
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/* Types ---------------------------------------------------------------------*/
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typedef int32_t lut_t[256][DECIMATION_MAX / 8][SINCN];
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typedef struct
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{
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/* Public */
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uint16_t LP_HZ;
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uint16_t HP_HZ;
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uint16_t Fs;
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unsigned int nSamples;
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uint8_t In_MicChannels;
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uint8_t Out_MicChannels;
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uint8_t Decimation;
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uint8_t MaxVolume;
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/* Private */
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uint32_t Coef[SINCN];
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uint16_t FilterLen;
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int64_t OldOut, OldIn, OldZ;
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uint16_t LP_ALFA;
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uint16_t HP_ALFA;
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uint16_t bit[5];
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uint16_t byte;
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uint32_t div_const;
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int64_t sub_const;
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uint32_t sinc[DECIMATION_MAX * SINCN];
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uint32_t sinc1[DECIMATION_MAX];
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uint32_t sinc2[DECIMATION_MAX * 2];
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uint32_t coef[SINCN][DECIMATION_MAX];
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#ifdef USE_LUT
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lut_t lut;
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#endif
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} TPDMFilter_InitStruct;
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/* Exported functions ------------------------------------------------------- */
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void Open_PDM_Filter_Init(TPDMFilter_InitStruct *init_struct);
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int Open_PDM_Filter_64(uint8_t *data, int16_t *data_out, uint16_t mic_gain, TPDMFilter_InitStruct *init_struct);
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#if DECIMATION_MAX == 128
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int Open_PDM_Filter_128(uint8_t *data, int16_t *data_out, uint16_t mic_gain, TPDMFilter_InitStruct *init_struct);
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#endif
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#ifdef __cplusplus
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}
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#endif
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#endif // __OPENPDMFILTER_H
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/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
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