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comparison spandsp-0.0.3/spandsp-0.0.3/src/spandsp/fir.h @ 5:f762bf195c4b

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import spandsp-0.0.3
author Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date Fri, 25 Jun 2010 16:00:21 +0200
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4:26cd8f1ef0b1 5:f762bf195c4b
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 typedef struct
76 {
77 int taps;
78 int curr_pos;
79 const int16_t *coeffs;
80 int16_t *history;
81 } fir16_state_t;
82
83 /*!
84 32 bit integer FIR descriptor. This defines the working state for a single
85 instance of an FIR filter using 32 bit integer coefficients, and filtering
86 16 bit integer data.
87 */
88 typedef struct
89 {
90 int taps;
91 int curr_pos;
92 const int32_t *coeffs;
93 int16_t *history;
94 } fir32_state_t;
95
96 /*!
97 Floating point FIR descriptor. This defines the working state for a single
98 instance of an FIR filter using floating point coefficients and data.
99 */
100 typedef struct
101 {
102 int taps;
103 int curr_pos;
104 const float *coeffs;
105 float *history;
106 } fir_float_state_t;
107
108 #ifdef __cplusplus
109 extern "C" {
110 #endif
111
112 static __inline__ const int16_t *fir16_create(fir16_state_t *fir,
113 const int16_t *coeffs,
114 int taps)
115 {
116 fir->taps = taps;
117 fir->curr_pos = taps - 1;
118 fir->coeffs = coeffs;
119 #if defined(USE_MMX) || defined(USE_SSE2) || defined(__BLACKFIN_ASM__)
120 if ((fir->history = malloc(2*taps*sizeof(int16_t))))
121 memset(fir->history, 0, 2*taps*sizeof(int16_t));
122 #else
123 if ((fir->history = (int16_t *) malloc(taps*sizeof(int16_t))))
124 memset(fir->history, 0, taps*sizeof(int16_t));
125 #endif
126 return fir->history;
127 }
128 /*- End of function --------------------------------------------------------*/
129
130 static __inline__ void fir16_flush(fir16_state_t *fir)
131 {
132 #if defined(USE_MMX) || defined(USE_SSE2) || defined(__BLACKFIN_ASM__)
133 memset(fir->history, 0, 2*fir->taps*sizeof(int16_t));
134 #else
135 memset(fir->history, 0, fir->taps*sizeof(int16_t));
136 #endif
137 }
138 /*- End of function --------------------------------------------------------*/
139
140 static __inline__ void fir16_free(fir16_state_t *fir)
141 {
142 free(fir->history);
143 }
144 /*- End of function --------------------------------------------------------*/
145
146 #ifdef __BLACKFIN_ASM__
147 static inline int32_t dot_asm(short *x, short *y, int len)
148 {
149 int dot;
150
151 len--;
152
153 __asm__
154 (
155 "I0 = %1;\n\t"
156 "I1 = %2;\n\t"
157 "A0 = 0;\n\t"
158 "R0.L = W[I0++] || R1.L = W[I1++];\n\t"
159 "LOOP dot%= LC0 = %3;\n\t"
160 "LOOP_BEGIN dot%=;\n\t"
161 "A0 += R0.L * R1.L (IS) || R0.L = W[I0++] || R1.L = W[I1++];\n\t"
162 "LOOP_END dot%=;\n\t"
163 "A0 += R0.L*R1.L (IS);\n\t"
164 "R0 = A0;\n\t"
165 "%0 = R0;\n\t"
166 : "=&d" (dot)
167 : "a" (x), "a" (y), "a" (len)
168 : "I0", "I1", "A1", "A0", "R0", "R1"
169 );
170
171 return dot;
172 }
173 #endif
174 /*- End of function --------------------------------------------------------*/
175
176 static __inline__ int16_t fir16(fir16_state_t *fir, int16_t sample)
177 {
178 int32_t y;
179 #if defined(USE_MMX)
180 int i;
181 mmx_t *mmx_coeffs;
182 mmx_t *mmx_hist;
183
184 fir->history[fir->curr_pos] = sample;
185 fir->history[fir->curr_pos + fir->taps] = sample;
186
187 mmx_coeffs = (mmx_t *) fir->coeffs;
188 mmx_hist = (mmx_t *) &fir->history[fir->curr_pos];
189 i = fir->taps;
190 pxor_r2r(mm4, mm4);
191 /* 8 samples per iteration, so the filter must be a multiple of 8 long. */
192 while (i > 0)
193 {
194 movq_m2r(mmx_coeffs[0], mm0);
195 movq_m2r(mmx_coeffs[1], mm2);
196 movq_m2r(mmx_hist[0], mm1);
197 movq_m2r(mmx_hist[1], mm3);
198 mmx_coeffs += 2;
199 mmx_hist += 2;
200 pmaddwd_r2r(mm1, mm0);
201 pmaddwd_r2r(mm3, mm2);
202 paddd_r2r(mm0, mm4);
203 paddd_r2r(mm2, mm4);
204 i -= 8;
205 }
206 movq_r2r(mm4, mm0);
207 psrlq_i2r(32, mm0);
208 paddd_r2r(mm0, mm4);
209 movd_r2m(mm4, y);
210 emms();
211 #elif defined(USE_SSE2)
212 int i;
213 xmm_t *xmm_coeffs;
214 xmm_t *xmm_hist;
215
216 fir->history[fir->curr_pos] = sample;
217 fir->history[fir->curr_pos + fir->taps] = sample;
218
219 xmm_coeffs = (xmm_t *) fir->coeffs;
220 xmm_hist = (xmm_t *) &fir->history[fir->curr_pos];
221 i = fir->taps;
222 pxor_r2r(xmm4, xmm4);
223 /* 16 samples per iteration, so the filter must be a multiple of 16 long. */
224 while (i > 0)
225 {
226 movdqu_m2r(xmm_coeffs[0], xmm0);
227 movdqu_m2r(xmm_coeffs[1], xmm2);
228 movdqu_m2r(xmm_hist[0], xmm1);
229 movdqu_m2r(xmm_hist[1], xmm3);
230 xmm_coeffs += 2;
231 xmm_hist += 2;
232 pmaddwd_r2r(xmm1, xmm0);
233 pmaddwd_r2r(xmm3, xmm2);
234 paddd_r2r(xmm0, xmm4);
235 paddd_r2r(xmm2, xmm4);
236 i -= 16;
237 }
238 movdqa_r2r(xmm4, xmm0);
239 psrldq_i2r(8, xmm0);
240 paddd_r2r(xmm0, xmm4);
241 movdqa_r2r(xmm4, xmm0);
242 psrldq_i2r(4, xmm0);
243 paddd_r2r(xmm0, xmm4);
244 movd_r2m(xmm4, y);
245 #elif defined(__BLACKFIN_ASM__)
246 fir->history[fir->curr_pos] = sample;
247 fir->history[fir->curr_pos + fir->taps] = sample;
248 y = dot_asm((int16_t*)fir->coeffs, &fir->history[fir->curr_pos], fir->taps);
249 #else
250 int i;
251 int offset1;
252 int offset2;
253
254 fir->history[fir->curr_pos] = sample;
255
256 offset2 = fir->curr_pos;
257 offset1 = fir->taps - offset2;
258 y = 0;
259 for (i = fir->taps - 1; i >= offset1; i--)
260 y += fir->coeffs[i]*fir->history[i - offset1];
261 for ( ; i >= 0; i--)
262 y += fir->coeffs[i]*fir->history[i + offset2];
263 #endif
264 if (fir->curr_pos <= 0)
265 fir->curr_pos = fir->taps;
266 fir->curr_pos--;
267 return (int16_t) (y >> 15);
268 }
269 /*- End of function --------------------------------------------------------*/
270
271 static __inline__ const int16_t *fir32_create(fir32_state_t *fir,
272 const int32_t *coeffs,
273 int taps)
274 {
275 fir->taps = taps;
276 fir->curr_pos = taps - 1;
277 fir->coeffs = coeffs;
278 fir->history = (int16_t *) malloc(taps*sizeof(int16_t));
279 if (fir->history)
280 memset(fir->history, '\0', taps*sizeof(int16_t));
281 return fir->history;
282 }
283 /*- End of function --------------------------------------------------------*/
284
285 static __inline__ void fir32_flush(fir32_state_t *fir)
286 {
287 memset(fir->history, 0, fir->taps*sizeof(int16_t));
288 }
289 /*- End of function --------------------------------------------------------*/
290
291 static __inline__ void fir32_free(fir32_state_t *fir)
292 {
293 free(fir->history);
294 }
295 /*- End of function --------------------------------------------------------*/
296
297 static __inline__ int16_t fir32(fir32_state_t *fir, int16_t sample)
298 {
299 int i;
300 int32_t y;
301 int offset1;
302 int offset2;
303
304 fir->history[fir->curr_pos] = sample;
305 offset2 = fir->curr_pos;
306 offset1 = fir->taps - offset2;
307 y = 0;
308 for (i = fir->taps - 1; i >= offset1; i--)
309 y += fir->coeffs[i]*fir->history[i - offset1];
310 for ( ; i >= 0; i--)
311 y += fir->coeffs[i]*fir->history[i + offset2];
312 if (fir->curr_pos <= 0)
313 fir->curr_pos = fir->taps;
314 fir->curr_pos--;
315 return (int16_t) (y >> 15);
316 }
317 /*- End of function --------------------------------------------------------*/
318
319 #ifndef __KERNEL__
320 static __inline__ const float *fir_float_create(fir_float_state_t *fir,
321 const float *coeffs,
322 int taps)
323 {
324 fir->taps = taps;
325 fir->curr_pos = taps - 1;
326 fir->coeffs = coeffs;
327 fir->history = (float *) malloc(taps*sizeof(float));
328 if (fir->history)
329 memset(fir->history, '\0', taps*sizeof(float));
330 return fir->history;
331 }
332 /*- End of function --------------------------------------------------------*/
333
334 static __inline__ void fir_float_free(fir_float_state_t *fir)
335 {
336 free(fir->history);
337 }
338 /*- End of function --------------------------------------------------------*/
339
340 static __inline__ int16_t fir_float(fir_float_state_t *fir, int16_t sample)
341 {
342 int i;
343 float y;
344 int offset1;
345 int offset2;
346
347 fir->history[fir->curr_pos] = sample;
348
349 offset2 = fir->curr_pos;
350 offset1 = fir->taps - offset2;
351 y = 0;
352 for (i = fir->taps - 1; i >= offset1; i--)
353 y += fir->coeffs[i]*fir->history[i - offset1];
354 for ( ; i >= 0; i--)
355 y += fir->coeffs[i]*fir->history[i + offset2];
356 if (fir->curr_pos <= 0)
357 fir->curr_pos = fir->taps;
358 fir->curr_pos--;
359 return (int16_t) y;
360 }
361 /*- End of function --------------------------------------------------------*/
362 #endif
363
364 #ifdef __cplusplus
365 }
366 #endif
367
368 #endif
369 /*- End of file ------------------------------------------------------------*/

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