/* * 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. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2, as * published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #if !defined(_FIR_H_)#define _FIR_H_ /*   Blackfin NOTES & IDEAS:    A simple dot product function is used to implement the filter.  This performs   just one MAC/cycle which is inefficient but was easy to implement as a first   pass.  The current Blackfin code also uses an unrolled form of the filter   history to avoid 0 length hardware loop issues.  This is wasteful of   memory.    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;#if defined(__bfin__)	fir->history = kcalloc(2 * taps, sizeof(int16_t), GFP_KERNEL);#else	fir->history = kcalloc(taps, sizeof(int16_t), GFP_KERNEL);#endif	return fir->history;} static inline void fir16_flush(struct fir16_state_t *fir){#if defined(__bfin__)	memset(fir->history, 0, 2 * fir->taps * sizeof(int16_t));#else	memset(fir->history, 0, fir->taps * sizeof(int16_t));#endif} static inline void fir16_free(struct fir16_state_t *fir){	kfree(fir->history);} #ifdef __bfin__static inline int32_t dot_asm(short *x, short *y, int len){	int dot; 	len--; 	__asm__("I0 = %1;\n\t"		"I1 = %2;\n\t"		"A0 = 0;\n\t"		"R0.L = W[I0++] || R1.L = W[I1++];\n\t"		"LOOP dot%= LC0 = %3;\n\t"		"LOOP_BEGIN dot%=;\n\t"		"A0 += R0.L * R1.L (IS) || R0.L = W[I0++] || R1.L = W[I1++];\n\t"		"LOOP_END dot%=;\n\t"		"A0 += R0.L*R1.L (IS);\n\t"		"R0 = A0;\n\t"		"%0 = R0;\n\t"		: "=&d"(dot)		: "a"(x), "a"(y), "a"(len)		: "I0", "I1", "A1", "A0", "R0", "R1"	); 	return dot;}#endif static inline int16_t fir16(struct fir16_state_t *fir, int16_t sample){	int32_t y;#if defined(__bfin__)	fir->history[fir->curr_pos] = sample;	fir->history[fir->curr_pos + fir->taps] = sample;	y = dot_asm((int16_t *) fir->coeffs, &fir->history[fir->curr_pos],		    fir->taps);#else	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];#endif	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