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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 | /* SPDX-License-Identifier: GPL-2.0-only */ /* * SpanDSP - a series of DSP components for telephony * * fir.h - General telephony FIR routines * * Written by Steve Underwood <steveu@coppice.org> * * Copyright (C) 2002 Steve Underwood * * All rights reserved. */ #if !defined(_FIR_H_) #define _FIR_H_ /* Ideas for improvement: 1/ Rewrite filter for dual MAC inner loop. The issue here is handling history sample offsets that are 16 bit aligned - the dual MAC needs 32 bit aligmnent. There are some good examples in libbfdsp. 2/ Use the hardware circular buffer facility tohalve memory usage. 3/ Consider using internal memory. Using less memory might also improve speed as cache misses will be reduced. A drop in MIPs and memory approaching 50% should be possible. The foreground and background filters currenlty use a total of about 10 MIPs/ch as measured with speedtest.c on a 256 TAP echo can. */ /* * 16 bit integer FIR descriptor. This defines the working state for a single * instance of an FIR filter using 16 bit integer coefficients. */ struct fir16_state_t { int taps; int curr_pos; const int16_t *coeffs; int16_t *history; }; /* * 32 bit integer FIR descriptor. This defines the working state for a single * instance of an FIR filter using 32 bit integer coefficients, and filtering * 16 bit integer data. */ struct fir32_state_t { int taps; int curr_pos; const int32_t *coeffs; int16_t *history; }; /* * Floating point FIR descriptor. This defines the working state for a single * instance of an FIR filter using floating point coefficients and data. */ struct fir_float_state_t { int taps; int curr_pos; const float *coeffs; float *history; }; static inline const int16_t *fir16_create(struct fir16_state_t *fir, const int16_t *coeffs, int taps) { fir->taps = taps; fir->curr_pos = taps - 1; fir->coeffs = coeffs; fir->history = kcalloc(taps, sizeof(int16_t), GFP_KERNEL); return fir->history; } static inline void fir16_flush(struct fir16_state_t *fir) { memset(fir->history, 0, fir->taps * sizeof(int16_t)); } static inline void fir16_free(struct fir16_state_t *fir) { kfree(fir->history); } static inline int16_t fir16(struct fir16_state_t *fir, int16_t sample) { int32_t y; int i; int offset1; int offset2; fir->history[fir->curr_pos] = sample; offset2 = fir->curr_pos; offset1 = fir->taps - offset2; y = 0; for (i = fir->taps - 1; i >= offset1; i--) y += fir->coeffs[i] * fir->history[i - offset1]; for (; i >= 0; i--) y += fir->coeffs[i] * fir->history[i + offset2]; if (fir->curr_pos <= 0) fir->curr_pos = fir->taps; fir->curr_pos--; return (int16_t) (y >> 15); } static inline const int16_t *fir32_create(struct fir32_state_t *fir, const int32_t *coeffs, int taps) { fir->taps = taps; fir->curr_pos = taps - 1; fir->coeffs = coeffs; fir->history = kcalloc(taps, sizeof(int16_t), GFP_KERNEL); return fir->history; } static inline void fir32_flush(struct fir32_state_t *fir) { memset(fir->history, 0, fir->taps * sizeof(int16_t)); } static inline void fir32_free(struct fir32_state_t *fir) { kfree(fir->history); } static inline int16_t fir32(struct fir32_state_t *fir, int16_t sample) { int i; int32_t y; int offset1; int offset2; fir->history[fir->curr_pos] = sample; offset2 = fir->curr_pos; offset1 = fir->taps - offset2; y = 0; for (i = fir->taps - 1; i >= offset1; i--) y += fir->coeffs[i] * fir->history[i - offset1]; for (; i >= 0; i--) y += fir->coeffs[i] * fir->history[i + offset2]; if (fir->curr_pos <= 0) fir->curr_pos = fir->taps; fir->curr_pos--; return (int16_t) (y >> 15); } #endif |