2 * SpanDSP - a series of DSP components for telephony
4 * fir.h - General telephony FIR routines
6 * Written by Steve Underwood <steveu@coppice.org>
8 * Copyright (C) 2002 Steve Underwood
10 * All rights reserved.
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.
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.
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.
25 * $Id: fir.h,v 1.8 2006/10/24 13:45:28 steveu Exp $
28 /*! \page fir_page FIR filtering
29 \section fir_page_sec_1 What does it do?
32 \section fir_page_sec_2 How does it work?
40 Blackfin NOTES & IDEAS:
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
48 Ideas for improvement:
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.
54 2/ Use the hardware circular buffer facility tohalve memory usage.
56 3/ Consider using internal memory.
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
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
67 #if defined(USE_MMX) || defined(USE_SSE2)
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.
79 const int16_t *coeffs
;
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
92 const int32_t *coeffs
;
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.
112 static __inline__
const int16_t *fir16_create(fir16_state_t
*fir
,
113 const int16_t *coeffs
,
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));
123 if ((fir
->history
= (int16_t *) malloc(taps
*sizeof(int16_t))))
124 memset(fir
->history
, 0, taps
*sizeof(int16_t));
128 /*- End of function --------------------------------------------------------*/
130 static __inline__
void fir16_flush(fir16_state_t
*fir
)
132 #if defined(USE_MMX) || defined(USE_SSE2) || defined(__BLACKFIN_ASM__)
133 memset(fir
->history
, 0, 2*fir
->taps
*sizeof(int16_t));
135 memset(fir
->history
, 0, fir
->taps
*sizeof(int16_t));
138 /*- End of function --------------------------------------------------------*/
140 static __inline__
void fir16_free(fir16_state_t
*fir
)
144 /*- End of function --------------------------------------------------------*/
146 #ifdef __BLACKFIN_ASM__
147 static inline int32_t dot_asm(short *x
, short *y
, int len
)
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"
167 : "a" (x
), "a" (y
), "a" (len
)
168 : "I0", "I1", "A1", "A0", "R0", "R1"
174 /*- End of function --------------------------------------------------------*/
176 static __inline__
int16_t fir16(fir16_state_t
*fir
, int16_t sample
)
184 fir
->history
[fir
->curr_pos
] = sample
;
185 fir
->history
[fir
->curr_pos
+ fir
->taps
] = sample
;
187 mmx_coeffs
= (mmx_t
*) fir
->coeffs
;
188 mmx_hist
= (mmx_t
*) &fir
->history
[fir
->curr_pos
];
191 /* 8 samples per iteration, so the filter must be a multiple of 8 long. */
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
);
200 pmaddwd_r2r(mm1
, mm0
);
201 pmaddwd_r2r(mm3
, mm2
);
211 #elif defined(USE_SSE2)
216 fir
->history
[fir
->curr_pos
] = sample
;
217 fir
->history
[fir
->curr_pos
+ fir
->taps
] = sample
;
219 xmm_coeffs
= (xmm_t
*) fir
->coeffs
;
220 xmm_hist
= (xmm_t
*) &fir
->history
[fir
->curr_pos
];
222 pxor_r2r(xmm4
, xmm4
);
223 /* 16 samples per iteration, so the filter must be a multiple of 16 long. */
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
);
232 pmaddwd_r2r(xmm1
, xmm0
);
233 pmaddwd_r2r(xmm3
, xmm2
);
234 paddd_r2r(xmm0
, xmm4
);
235 paddd_r2r(xmm2
, xmm4
);
238 movdqa_r2r(xmm4
, xmm0
);
240 paddd_r2r(xmm0
, xmm4
);
241 movdqa_r2r(xmm4
, xmm0
);
243 paddd_r2r(xmm0
, xmm4
);
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
);
254 fir
->history
[fir
->curr_pos
] = sample
;
256 offset2
= fir
->curr_pos
;
257 offset1
= fir
->taps
- offset2
;
259 for (i
= fir
->taps
- 1; i
>= offset1
; i
--)
260 y
+= fir
->coeffs
[i
]*fir
->history
[i
- offset1
];
262 y
+= fir
->coeffs
[i
]*fir
->history
[i
+ offset2
];
264 if (fir
->curr_pos
<= 0)
265 fir
->curr_pos
= fir
->taps
;
267 return (int16_t) (y
>> 15);
269 /*- End of function --------------------------------------------------------*/
271 static __inline__
const int16_t *fir32_create(fir32_state_t
*fir
,
272 const int32_t *coeffs
,
276 fir
->curr_pos
= taps
- 1;
277 fir
->coeffs
= coeffs
;
278 fir
->history
= (int16_t *) malloc(taps
*sizeof(int16_t));
280 memset(fir
->history
, '\0', taps
*sizeof(int16_t));
283 /*- End of function --------------------------------------------------------*/
285 static __inline__
void fir32_flush(fir32_state_t
*fir
)
287 memset(fir
->history
, 0, fir
->taps
*sizeof(int16_t));
289 /*- End of function --------------------------------------------------------*/
291 static __inline__
void fir32_free(fir32_state_t
*fir
)
295 /*- End of function --------------------------------------------------------*/
297 static __inline__
int16_t fir32(fir32_state_t
*fir
, int16_t sample
)
304 fir
->history
[fir
->curr_pos
] = sample
;
305 offset2
= fir
->curr_pos
;
306 offset1
= fir
->taps
- offset2
;
308 for (i
= fir
->taps
- 1; i
>= offset1
; i
--)
309 y
+= fir
->coeffs
[i
]*fir
->history
[i
- offset1
];
311 y
+= fir
->coeffs
[i
]*fir
->history
[i
+ offset2
];
312 if (fir
->curr_pos
<= 0)
313 fir
->curr_pos
= fir
->taps
;
315 return (int16_t) (y
>> 15);
317 /*- End of function --------------------------------------------------------*/
320 static __inline__
const float *fir_float_create(fir_float_state_t
*fir
,
325 fir
->curr_pos
= taps
- 1;
326 fir
->coeffs
= coeffs
;
327 fir
->history
= (float *) malloc(taps
*sizeof(float));
329 memset(fir
->history
, '\0', taps
*sizeof(float));
332 /*- End of function --------------------------------------------------------*/
334 static __inline__
void fir_float_free(fir_float_state_t
*fir
)
338 /*- End of function --------------------------------------------------------*/
340 static __inline__
int16_t fir_float(fir_float_state_t
*fir
, int16_t sample
)
347 fir
->history
[fir
->curr_pos
] = sample
;
349 offset2
= fir
->curr_pos
;
350 offset1
= fir
->taps
- offset2
;
352 for (i
= fir
->taps
- 1; i
>= offset1
; i
--)
353 y
+= fir
->coeffs
[i
]*fir
->history
[i
- offset1
];
355 y
+= fir
->coeffs
[i
]*fir
->history
[i
+ offset2
];
356 if (fir
->curr_pos
<= 0)
357 fir
->curr_pos
= fir
->taps
;
361 /*- End of function --------------------------------------------------------*/
369 /*- End of file ------------------------------------------------------------*/