micropython · iabdalkader · Jan 20, 2022 · Jan 20, 2022
diff --git a/lib/openpdm/pdm_filter.c b/lib/openpdm/pdm_filter.c
@@ -0,0 +1,306 @@
+/**
+ *******************************************************************************
+ * @file    OpenPDMFilter.c
+ * @author  CL
+ * @version V1.0.0
+ * @date    9-September-2015
+ * @brief   Open PDM audio software decoding Library.
+ *          This Library is used to decode and reconstruct the audio signal
+ *          produced by ST MEMS microphone (MP45Dxxx, MP34Dxxx).
+ *******************************************************************************
+ * @attention
+ *
+ * <h2><center>&copy; COPYRIGHT 2018 STMicroelectronics</center></h2>
+ *
+ * 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
+ *
+ *  http://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.
+ *******************************************************************************
+ */
+
+
+/* Includes ------------------------------------------------------------------*/
+
+#include "pdm_filter.h"
+
+
+/* Variables -----------------------------------------------------------------*/
+
+uint32_t div_const = 0;
+int64_t sub_const = 0;
+uint32_t sinc[DECIMATION_MAX * SINCN];
+uint32_t sinc1[DECIMATION_MAX];
+uint32_t sinc2[DECIMATION_MAX * 2];
+uint32_t coef[SINCN][DECIMATION_MAX];
+#ifdef USE_LUT
+#include "pdm_filter_lut.c"
+#endif
+
+
+/* Functions -----------------------------------------------------------------*/
+
+#ifdef USE_LUT
+int32_t filter_table_mono_64(uint8_t *data, uint8_t sincn) {
+    return (int32_t)
+           pdm_lut64[data[0]][0][sincn] +
+           pdm_lut64[data[1]][1][sincn] +
+           pdm_lut64[data[2]][2][sincn] +
+           pdm_lut64[data[3]][3][sincn] +
+           pdm_lut64[data[4]][4][sincn] +
+           pdm_lut64[data[5]][5][sincn] +
+           pdm_lut64[data[6]][6][sincn] +
+           pdm_lut64[data[7]][7][sincn];
+}
+int32_t filter_table_stereo_64(uint8_t *data, uint8_t sincn) {
+    return (int32_t)
+           pdm_lut64[data[0]][0][sincn] +
+           pdm_lut64[data[2]][1][sincn] +
+           pdm_lut64[data[4]][2][sincn] +
+           pdm_lut64[data[6]][3][sincn] +
+           pdm_lut64[data[8]][4][sincn] +
+           pdm_lut64[data[10]][5][sincn] +
+           pdm_lut64[data[12]][6][sincn] +
+           pdm_lut64[data[14]][7][sincn];
+}
+int32_t filter_table_mono_128(uint8_t *data, uint8_t sincn) {
+    return (int32_t)
+           pdm_lut128[data[0]][0][sincn] +
+           pdm_lut128[data[1]][1][sincn] +
+           pdm_lut128[data[2]][2][sincn] +
+           pdm_lut128[data[3]][3][sincn] +
+           pdm_lut128[data[4]][4][sincn] +
+           pdm_lut128[data[5]][5][sincn] +
+           pdm_lut128[data[6]][6][sincn] +
+           pdm_lut128[data[7]][7][sincn] +
+           pdm_lut128[data[8]][8][sincn] +
+           pdm_lut128[data[9]][9][sincn] +
+           pdm_lut128[data[10]][10][sincn] +
+           pdm_lut128[data[11]][11][sincn] +
+           pdm_lut128[data[12]][12][sincn] +
+           pdm_lut128[data[13]][13][sincn] +
+           pdm_lut128[data[14]][14][sincn] +
+           pdm_lut128[data[15]][15][sincn];
+}
+int32_t filter_table_stereo_128(uint8_t *data, uint8_t sincn) {
+    return (int32_t)
+           pdm_lut128[data[0]][0][sincn] +
+           pdm_lut128[data[2]][1][sincn] +
+           pdm_lut128[data[4]][2][sincn] +
+           pdm_lut128[data[6]][3][sincn] +
+           pdm_lut128[data[8]][4][sincn] +
+           pdm_lut128[data[10]][5][sincn] +
+           pdm_lut128[data[12]][6][sincn] +
+           pdm_lut128[data[14]][7][sincn] +
+           pdm_lut128[data[16]][8][sincn] +
+           pdm_lut128[data[18]][9][sincn] +
+           pdm_lut128[data[20]][10][sincn] +
+           pdm_lut128[data[22]][11][sincn] +
+           pdm_lut128[data[24]][12][sincn] +
+           pdm_lut128[data[26]][13][sincn] +
+           pdm_lut128[data[28]][14][sincn] +
+           pdm_lut128[data[30]][15][sincn];
+}
+int32_t (*filter_tables_64[2])(uint8_t *data, uint8_t sincn) = {filter_table_mono_64, filter_table_stereo_64};
+int32_t (*filter_tables_128[2])(uint8_t *data, uint8_t sincn) = {filter_table_mono_128, filter_table_stereo_128};
+#else
+int32_t filter_table(uint8_t *data, uint8_t sincn, TPDMFilter_InitStruct *param) {
+    uint8_t c, i;
+    uint16_t data_index = 0;
+    uint32_t *coef_p = &coef[sincn][0];
+    int32_t F = 0;
+    uint8_t decimation = param->Decimation;
+    uint8_t channels = param->In_MicChannels;
+
+    for (i = 0; i < decimation; i += 8) {
+        c = data[data_index];
+        F += ((c >> 7)) * coef_p[i    ] +
+            ((c >> 6) & 0x01) * coef_p[i + 1] +
+            ((c >> 5) & 0x01) * coef_p[i + 2] +
+            ((c >> 4) & 0x01) * coef_p[i + 3] +
+            ((c >> 3) & 0x01) * coef_p[i + 4] +
+            ((c >> 2) & 0x01) * coef_p[i + 5] +
+            ((c >> 1) & 0x01) * coef_p[i + 6] +
+            ((c) & 0x01) * coef_p[i + 7];
+        data_index += channels;
+    }
+    return F;
+}
+#endif
+
+void convolve(uint32_t Signal[] /* SignalLen */, unsigned short SignalLen,
+    uint32_t Kernel[] /* KernelLen */, unsigned short KernelLen,
+    uint32_t Result[] /* SignalLen + KernelLen - 1 */) {
+    uint16_t n;
+
+    for (n = 0; n < SignalLen + KernelLen - 1; n++)
+    {
+        unsigned short kmin, kmax, k;
+
+        Result[n] = 0;
+
+        kmin = (n >= KernelLen - 1) ? n - (KernelLen - 1) : 0;
+        kmax = (n < SignalLen - 1) ? n : SignalLen - 1;
+
+        for (k = kmin; k <= kmax; k++) {
+            Result[n] += Signal[k] * Kernel[n - k];
+        }
+    }
+}
+
+void Open_PDM_Filter_Init(TPDMFilter_InitStruct *Param) {
+    uint16_t i, j;
+    int64_t sum = 0;
+
+    uint8_t decimation = Param->Decimation;
+
+    for (i = 0; i < SINCN; i++) {
+        Param->Coef[i] = 0;
+        Param->bit[i] = 0;
+    }
+    for (i = 0; i < decimation; i++) {
+        sinc1[i] = 1;
+    }
+
+    Param->OldOut = Param->OldIn = Param->OldZ = 0;
+    Param->LP_ALFA = (Param->LP_HZ != 0 ? (uint16_t)(Param->LP_HZ * 256 / (Param->LP_HZ + Param->Fs / (2 * 3.14159))) : 0);
+    Param->HP_ALFA = (Param->HP_HZ != 0 ? (uint16_t)(Param->Fs * 256 / (2 * 3.14159 * Param->HP_HZ + Param->Fs)) : 0);
+
+    Param->FilterLen = decimation * SINCN;
+    sinc[0] = 0;
+    sinc[decimation * SINCN - 1] = 0;
+    convolve(sinc1, decimation, sinc1, decimation, sinc2);
+    convolve(sinc2, decimation * 2 - 1, sinc1, decimation, &sinc[1]);
+    for (j = 0; j < SINCN; j++) {
+        for (i = 0; i < decimation; i++) {
+            coef[j][i] = sinc[j * decimation + i];
+            sum += sinc[j * decimation + i];
+        }
+    }
+
+    sub_const = sum >> 1;
+    div_const = sub_const * Param->MaxVolume / 32768 / Param->filterGain;
+    div_const = (div_const == 0 ? 1 : div_const);
+
+    #if 0 // USE_LUT
+    /* Look-Up Table. */
+    uint16_t c, d, s;
+    for (s = 0; s < SINCN; s++)
+    {
+        uint32_t *coef_p = &coef[s][0];
+        for (c = 0; c < 256; c++) {
+            for (d = 0; d < decimation / 8; d++) {
+                lut[c][d][s] = ((c >> 7)) * coef_p[d * 8    ] +
+                    ((c >> 6) & 0x01) * coef_p[d * 8 + 1] +
+                    ((c >> 5) & 0x01) * coef_p[d * 8 + 2] +
+                    ((c >> 4) & 0x01) * coef_p[d * 8 + 3] +
+                    ((c >> 3) & 0x01) * coef_p[d * 8 + 4] +
+                    ((c >> 2) & 0x01) * coef_p[d * 8 + 5] +
+                    ((c >> 1) & 0x01) * coef_p[d * 8 + 6] +
+                    ((c) & 0x01) * coef_p[d * 8 + 7];
+            }
+        }
+    }
+    #endif
+}
+
+void Open_PDM_Filter_64(uint8_t *data, int16_t *dataOut, uint16_t volume, TPDMFilter_InitStruct *Param) {
+    uint8_t i, data_out_index;
+    uint8_t channels = Param->In_MicChannels;
+    uint8_t data_inc = ((DECIMATION_MAX >> 4) * channels);
+    int64_t Z, Z0, Z1, Z2;
+    int64_t OldOut, OldIn, OldZ;
+
+    OldOut = Param->OldOut;
+    OldIn = Param->OldIn;
+    OldZ = Param->OldZ;
+
+    #ifdef USE_LUT
+    uint8_t j = channels - 1;
+    #endif
+
+    for (i = 0, data_out_index = 0; i < Param->nSamples; i++, data_out_index += channels) {
+        #ifdef USE_LUT
+        Z0 = filter_tables_64[j](data, 0);
+        Z1 = filter_tables_64[j](data, 1);
+        Z2 = filter_tables_64[j](data, 2);
+        #else
+        Z0 = filter_table(data, 0, Param);
+        Z1 = filter_table(data, 1, Param);
+        Z2 = filter_table(data, 2, Param);
+        #endif
+
+        Z = Param->Coef[1] + Z2 - sub_const;
+        Param->Coef[1] = Param->Coef[0] + Z1;
+        Param->Coef[0] = Z0;
+
+        OldOut = (Param->HP_ALFA * (OldOut + Z - OldIn)) >> 8;
+        OldIn = Z;
+        OldZ = ((256 - Param->LP_ALFA) * OldZ + Param->LP_ALFA * OldOut) >> 8;
+
+        Z = OldZ * volume;
+        Z = RoundDiv(Z, div_const);
+        Z = SaturaLH(Z, -32700, 32700);
+
+        dataOut[data_out_index] = Z;
+        data += data_inc;
+    }
+
+    Param->OldOut = OldOut;
+    Param->OldIn = OldIn;
+    Param->OldZ = OldZ;
+}
+
+void Open_PDM_Filter_128(uint8_t *data, int16_t *dataOut, uint16_t volume, TPDMFilter_InitStruct *Param) {
+    uint8_t i, data_out_index;
+    uint8_t channels = Param->In_MicChannels;
+    uint8_t data_inc = ((DECIMATION_MAX >> 3) * channels);
+    int64_t Z, Z0, Z1, Z2;
+    int64_t OldOut, OldIn, OldZ;
+
+    OldOut = Param->OldOut;
+    OldIn = Param->OldIn;
+    OldZ = Param->OldZ;
+
+    #ifdef USE_LUT
+    uint8_t j = channels - 1;
+    #endif
+
+    for (i = 0, data_out_index = 0; i < Param->nSamples; i++, data_out_index += channels) {
+        #ifdef USE_LUT
+        Z0 = filter_tables_128[j](data, 0);
+        Z1 = filter_tables_128[j](data, 1);
+        Z2 = filter_tables_128[j](data, 2);
+        #else
+        Z0 = filter_table(data, 0, Param);
+        Z1 = filter_table(data, 1, Param);
+        Z2 = filter_table(data, 2, Param);
+        #endif
+
+        Z = Param->Coef[1] + Z2 - sub_const;
+        Param->Coef[1] = Param->Coef[0] + Z1;
+        Param->Coef[0] = Z0;
+
+        OldOut = (Param->HP_ALFA * (OldOut + Z - OldIn)) >> 8;
+        OldIn = Z;
+        OldZ = ((256 - Param->LP_ALFA) * OldZ + Param->LP_ALFA * OldOut) >> 8;
+
+        Z = OldZ * volume;
+        Z = RoundDiv(Z, div_const);
+        Z = SaturaLH(Z, -32700, 32700);
+
+        dataOut[data_out_index] = Z;
+        data += data_inc;
+    }
+
+    Param->OldOut = OldOut;
+    Param->OldIn = OldIn;
+    Param->OldZ = OldZ;
+}