1 /*
2 * SpanDSP - a series of DSP components for telephony
3 *
4 * fir.h - General telephony FIR routines
5 *
6 * Written by Steve Underwood <steveu@coppice.org>
7 *
8 * Copyright (C) 2002 Steve Underwood
9 *
10 * All rights reserved.
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2, as
14 * published by the Free Software Foundation.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 *
25 * $Id: fir.h,v 1.8 2006/10/24 13:45:28 steveu Exp $
26 */
27
28 /*! \page fir_page FIR filtering
29 \section fir_page_sec_1 What does it do?
30 ???.
31
32 \section fir_page_sec_2 How does it work?
33 ???.
34 */
35
36 #if !defined(_FIR_H_)
37 #define _FIR_H_
38
39 /*
40 Blackfin NOTES & IDEAS:
41
42 A simple dot product function is used to implement the filter. This performs
43 just one MAC/cycle which is inefficient but was easy to implement as a first
44 pass. The current Blackfin code also uses an unrolled form of the filter
45 history to avoid 0 length hardware loop issues. This is wasteful of
46 memory.
47
48 Ideas for improvement:
49
50 1/ Rewrite filter for dual MAC inner loop. The issue here is handling
51 history sample offsets that are 16 bit aligned - the dual MAC needs
52 32 bit aligmnent. There are some good examples in libbfdsp.
53
54 2/ Use the hardware circular buffer facility tohalve memory usage.
55
56 3/ Consider using internal memory.
57
58 Using less memory might also improve speed as cache misses will be
59 reduced. A drop in MIPs and memory approaching 50% should be
60 possible.
61
62 The foreground and background filters currenlty use a total of
63 about 10 MIPs/ch as measured with speedtest.c on a 256 TAP echo
64 can.
65 */
66
67 #if defined(USE_MMX) || defined(USE_SSE2)
68 #include "mmx.h"
69 #endif
70
71 /*!
72 16 bit integer FIR descriptor. This defines the working state for a single
73 instance of an FIR filter using 16 bit integer coefficients.
74 */
75 struct fir16_state_t {
76 int taps;
77 int curr_pos;
78 const int16_t *coeffs;
79 int16_t *history;
80 };
81
82 /*!
83 32 bit integer FIR descriptor. This defines the working state for a single
84 instance of an FIR filter using 32 bit integer coefficients, and filtering
85 16 bit integer data.
86 */
87 struct fir32_state_t {
88 int taps;
89 int curr_pos;
90 const int32_t *coeffs;
91 int16_t *history;
92 };
93
94 /*!
95 Floating point FIR descriptor. This defines the working state for a single
96 instance of an FIR filter using floating point coefficients and data.
97 */
98 struct fir_float_state_t {
99 int taps;
100 int curr_pos;
101 const float *coeffs;
102 float *history;
103 };
104
fir16_create(struct fir16_state_t * fir,const int16_t * coeffs,int taps)105 static __inline__ const int16_t *fir16_create(struct fir16_state_t *fir,
106 const int16_t * coeffs, int taps)
107 {
108 fir->taps = taps;
109 fir->curr_pos = taps - 1;
110 fir->coeffs = coeffs;
111 #if defined(USE_MMX) || defined(USE_SSE2) || defined(__bfin__)
112 fir->history = kcalloc(2 * taps, sizeof(int16_t), GFP_KERNEL);
113 #else
114 fir->history = kcalloc(taps, sizeof(int16_t), GFP_KERNEL);
115 #endif
116 return fir->history;
117 }
118
fir16_flush(struct fir16_state_t * fir)119 static __inline__ void fir16_flush(struct fir16_state_t *fir)
120 {
121 #if defined(USE_MMX) || defined(USE_SSE2) || defined(__bfin__)
122 memset(fir->history, 0, 2 * fir->taps * sizeof(int16_t));
123 #else
124 memset(fir->history, 0, fir->taps * sizeof(int16_t));
125 #endif
126 }
127
fir16_free(struct fir16_state_t * fir)128 static __inline__ void fir16_free(struct fir16_state_t *fir)
129 {
130 kfree(fir->history);
131 }
132
133 #ifdef __bfin__
dot_asm(short * x,short * y,int len)134 static inline int32_t dot_asm(short *x, short *y, int len)
135 {
136 int dot;
137
138 len--;
139
140 __asm__("I0 = %1;\n\t"
141 "I1 = %2;\n\t"
142 "A0 = 0;\n\t"
143 "R0.L = W[I0++] || R1.L = W[I1++];\n\t"
144 "LOOP dot%= LC0 = %3;\n\t"
145 "LOOP_BEGIN dot%=;\n\t"
146 "A0 += R0.L * R1.L (IS) || R0.L = W[I0++] || R1.L = W[I1++];\n\t"
147 "LOOP_END dot%=;\n\t"
148 "A0 += R0.L*R1.L (IS);\n\t"
149 "R0 = A0;\n\t"
150 "%0 = R0;\n\t"
151 :"=&d"(dot)
152 :"a"(x), "a"(y), "a"(len)
153 :"I0", "I1", "A1", "A0", "R0", "R1"
154 );
155
156 return dot;
157 }
158 #endif
159
fir16(struct fir16_state_t * fir,int16_t sample)160 static __inline__ int16_t fir16(struct fir16_state_t *fir, int16_t sample)
161 {
162 int32_t y;
163 #if defined(USE_MMX)
164 int i;
165 union mmx_t *mmx_coeffs;
166 union mmx_t *mmx_hist;
167
168 fir->history[fir->curr_pos] = sample;
169 fir->history[fir->curr_pos + fir->taps] = sample;
170
171 mmx_coeffs = (union mmx_t *)fir->coeffs;
172 mmx_hist = (union mmx_t *)&fir->history[fir->curr_pos];
173 i = fir->taps;
174 pxor_r2r(mm4, mm4);
175 /* 8 samples per iteration, so the filter must be a multiple of 8 long. */
176 while (i > 0) {
177 movq_m2r(mmx_coeffs[0], mm0);
178 movq_m2r(mmx_coeffs[1], mm2);
179 movq_m2r(mmx_hist[0], mm1);
180 movq_m2r(mmx_hist[1], mm3);
181 mmx_coeffs += 2;
182 mmx_hist += 2;
183 pmaddwd_r2r(mm1, mm0);
184 pmaddwd_r2r(mm3, mm2);
185 paddd_r2r(mm0, mm4);
186 paddd_r2r(mm2, mm4);
187 i -= 8;
188 }
189 movq_r2r(mm4, mm0);
190 psrlq_i2r(32, mm0);
191 paddd_r2r(mm0, mm4);
192 movd_r2m(mm4, y);
193 emms();
194 #elif defined(USE_SSE2)
195 int i;
196 union xmm_t *xmm_coeffs;
197 union xmm_t *xmm_hist;
198
199 fir->history[fir->curr_pos] = sample;
200 fir->history[fir->curr_pos + fir->taps] = sample;
201
202 xmm_coeffs = (union xmm_t *)fir->coeffs;
203 xmm_hist = (union xmm_t *)&fir->history[fir->curr_pos];
204 i = fir->taps;
205 pxor_r2r(xmm4, xmm4);
206 /* 16 samples per iteration, so the filter must be a multiple of 16 long. */
207 while (i > 0) {
208 movdqu_m2r(xmm_coeffs[0], xmm0);
209 movdqu_m2r(xmm_coeffs[1], xmm2);
210 movdqu_m2r(xmm_hist[0], xmm1);
211 movdqu_m2r(xmm_hist[1], xmm3);
212 xmm_coeffs += 2;
213 xmm_hist += 2;
214 pmaddwd_r2r(xmm1, xmm0);
215 pmaddwd_r2r(xmm3, xmm2);
216 paddd_r2r(xmm0, xmm4);
217 paddd_r2r(xmm2, xmm4);
218 i -= 16;
219 }
220 movdqa_r2r(xmm4, xmm0);
221 psrldq_i2r(8, xmm0);
222 paddd_r2r(xmm0, xmm4);
223 movdqa_r2r(xmm4, xmm0);
224 psrldq_i2r(4, xmm0);
225 paddd_r2r(xmm0, xmm4);
226 movd_r2m(xmm4, y);
227 #elif defined(__bfin__)
228 fir->history[fir->curr_pos] = sample;
229 fir->history[fir->curr_pos + fir->taps] = sample;
230 y = dot_asm((int16_t *) fir->coeffs, &fir->history[fir->curr_pos],
231 fir->taps);
232 #else
233 int i;
234 int offset1;
235 int offset2;
236
237 fir->history[fir->curr_pos] = sample;
238
239 offset2 = fir->curr_pos;
240 offset1 = fir->taps - offset2;
241 y = 0;
242 for (i = fir->taps - 1; i >= offset1; i--)
243 y += fir->coeffs[i] * fir->history[i - offset1];
244 for (; i >= 0; i--)
245 y += fir->coeffs[i] * fir->history[i + offset2];
246 #endif
247 if (fir->curr_pos <= 0)
248 fir->curr_pos = fir->taps;
249 fir->curr_pos--;
250 return (int16_t) (y >> 15);
251 }
252
fir32_create(struct fir32_state_t * fir,const int32_t * coeffs,int taps)253 static __inline__ const int16_t *fir32_create(struct fir32_state_t *fir,
254 const int32_t * coeffs, int taps)
255 {
256 fir->taps = taps;
257 fir->curr_pos = taps - 1;
258 fir->coeffs = coeffs;
259 fir->history = kcalloc(taps, sizeof(int16_t), GFP_KERNEL);
260 return fir->history;
261 }
262
fir32_flush(struct fir32_state_t * fir)263 static __inline__ void fir32_flush(struct fir32_state_t *fir)
264 {
265 memset(fir->history, 0, fir->taps * sizeof(int16_t));
266 }
267
fir32_free(struct fir32_state_t * fir)268 static __inline__ void fir32_free(struct fir32_state_t *fir)
269 {
270 kfree(fir->history);
271 }
272
fir32(struct fir32_state_t * fir,int16_t sample)273 static __inline__ int16_t fir32(struct fir32_state_t *fir, int16_t sample)
274 {
275 int i;
276 int32_t y;
277 int offset1;
278 int offset2;
279
280 fir->history[fir->curr_pos] = sample;
281 offset2 = fir->curr_pos;
282 offset1 = fir->taps - offset2;
283 y = 0;
284 for (i = fir->taps - 1; i >= offset1; i--)
285 y += fir->coeffs[i] * fir->history[i - offset1];
286 for (; i >= 0; i--)
287 y += fir->coeffs[i] * fir->history[i + offset2];
288 if (fir->curr_pos <= 0)
289 fir->curr_pos = fir->taps;
290 fir->curr_pos--;
291 return (int16_t) (y >> 15);
292 }
293
294 #endif
295 /*- End of file ------------------------------------------------------------*/
296