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
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/>
<meta http-equiv="X-UA-Compatible" content="IE=9"/>
<title>Finite Impulse Response (FIR) Sparse Filters</title>
<title>CMSIS-DSP: Finite Impulse Response (FIR) Sparse Filters</title>
<link href="tabs.css" rel="stylesheet" type="text/css"/>
<link href="cmsis.css" rel="stylesheet" type="text/css" />
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript" src="dynsections.js"></script>
<script type="text/javascript" src="printComponentTabs.js"></script>
<link href="navtree.css" rel="stylesheet" type="text/css"/>
<script type="text/javascript" src="resize.js"></script>
<script type="text/javascript" src="navtree.js"></script>
<script type="text/javascript">
$(document).ready(initResizable);
$(window).load(resizeHeight);
</script>
<link href="search/search.css" rel="stylesheet" type="text/css"/>
<script type="text/javascript" src="search/search.js"></script>
<script type="text/javascript">
$(document).ready(function() { searchBox.OnSelectItem(0); });
</script>
</head>
<body>
<div id="top"><!-- do not remove this div, it is closed by doxygen! -->
<div id="titlearea">
<table cellspacing="0" cellpadding="0">
<tbody>
<tr style="height: 46px;">
<td id="projectlogo"><img alt="Logo" src="CMSIS_Logo_Final.png"/></td>
<td style="padding-left: 0.5em;">
<div id="projectname">CMSIS-DSP
 <span id="projectnumber">Version 1.7.0</span>
</div>
<div id="projectbrief">CMSIS DSP Software Library</div>
</td>
</tr>
</tbody>
</table>
</div>
<!-- end header part -->
<div id="CMSISnav" class="tabs1">
<ul class="tablist">
<script type="text/javascript">
<!--
writeComponentTabs.call(this);
//-->
</script>
</ul>
</div>
<!-- Generated by Doxygen 1.8.6 -->
<script type="text/javascript">
var searchBox = new SearchBox("searchBox", "search",false,'Search');
</script>
<div id="navrow1" class="tabs">
<ul class="tablist">
<li><a href="index.html"><span>Main Page</span></a></li>
<li><a href="pages.html"><span>Usage and Description</span></a></li>
<li><a href="modules.html"><span>Reference</span></a></li>
<li>
<div id="MSearchBox" class="MSearchBoxInactive">
<span class="left">
<img id="MSearchSelect" src="search/mag_sel.png"
onmouseover="return searchBox.OnSearchSelectShow()"
onmouseout="return searchBox.OnSearchSelectHide()"
alt=""/>
<input type="text" id="MSearchField" value="Search" accesskey="S"
onfocus="searchBox.OnSearchFieldFocus(true)"
onblur="searchBox.OnSearchFieldFocus(false)"
onkeyup="searchBox.OnSearchFieldChange(event)"/>
</span><span class="right">
<a id="MSearchClose" href="javascript:searchBox.CloseResultsWindow()"><img id="MSearchCloseImg" border="0" src="search/close.png" alt=""/></a>
</span>
</div>
</li>
</ul>
</div>
</div><!-- top -->
<div id="side-nav" class="ui-resizable side-nav-resizable">
<div id="nav-tree">
<div id="nav-tree-contents">
<div id="nav-sync" class="sync"></div>
</div>
</div>
<div id="splitbar" style="-moz-user-select:none;"
class="ui-resizable-handle">
</div>
</div>
<script type="text/javascript">
$(document).ready(function(){initNavTree('group__FIR__Sparse.html','');});
</script>
<div id="doc-content">
<!-- window showing the filter options -->
<div id="MSearchSelectWindow"
onmouseover="return searchBox.OnSearchSelectShow()"
onmouseout="return searchBox.OnSearchSelectHide()"
onkeydown="return searchBox.OnSearchSelectKey(event)">
<a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(0)"><span class="SelectionMark"> </span>All</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(1)"><span class="SelectionMark"> </span>Data Structures</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(2)"><span class="SelectionMark"> </span>Files</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(3)"><span class="SelectionMark"> </span>Functions</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(4)"><span class="SelectionMark"> </span>Variables</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(5)"><span class="SelectionMark"> </span>Typedefs</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(6)"><span class="SelectionMark"> </span>Enumerations</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(7)"><span class="SelectionMark"> </span>Enumerator</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(8)"><span class="SelectionMark"> </span>Macros</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(9)"><span class="SelectionMark"> </span>Groups</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(10)"><span class="SelectionMark"> </span>Pages</a></div>
<!-- iframe showing the search results (closed by default) -->
<div id="MSearchResultsWindow">
<iframe src="javascript:void(0)" frameborder="0"
name="MSearchResults" id="MSearchResults">
</iframe>
</div>
<div class="header">
<div class="summary">
<a href="#func-members">Functions</a> </div>
<div class="headertitle">
<div class="title">Finite Impulse Response (FIR) Sparse Filters<div class="ingroups"><a class="el" href="group__groupFilters.html">Filtering Functions</a></div></div> </div>
</div><!--header-->
<div class="contents">
<table class="memberdecls">
<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="func-members"></a>
Functions</h2></td></tr>
<tr class="memitem:gac6817bc86974b7121c3288fce25dbc5f"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__FIR__Sparse.html#gac6817bc86974b7121c3288fce25dbc5f">arm_fir_sparse_f32</a> (<a class="el" href="structarm__fir__sparse__instance__f32.html">arm_fir_sparse_instance_f32</a> *S, const <a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> *pSrc, <a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> *pDst, <a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> *pScratchIn, uint32_t <a class="el" href="arm__variance__example__f32_8c.html#ab6558f40a619c2502fbc24c880fd4fb0">blockSize</a>)</td></tr>
<tr class="memdesc:gac6817bc86974b7121c3288fce25dbc5f"><td class="mdescLeft"> </td><td class="mdescRight">Processing function for the floating-point sparse FIR filter. <a href="#gac6817bc86974b7121c3288fce25dbc5f">More...</a><br/></td></tr>
<tr class="separator:gac6817bc86974b7121c3288fce25dbc5f"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:ga967a0564d6d59f2b9e12f4a5b7a3f877"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__FIR__Sparse.html#ga967a0564d6d59f2b9e12f4a5b7a3f877">arm_fir_sparse_init_f32</a> (<a class="el" href="structarm__fir__sparse__instance__f32.html">arm_fir_sparse_instance_f32</a> *S, uint16_t numTaps, const <a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> *pCoeffs, <a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> *pState, int32_t *pTapDelay, uint16_t maxDelay, uint32_t <a class="el" href="arm__variance__example__f32_8c.html#ab6558f40a619c2502fbc24c880fd4fb0">blockSize</a>)</td></tr>
<tr class="memdesc:ga967a0564d6d59f2b9e12f4a5b7a3f877"><td class="mdescLeft"> </td><td class="mdescRight">Initialization function for the floating-point sparse FIR filter. <a href="#ga967a0564d6d59f2b9e12f4a5b7a3f877">More...</a><br/></td></tr>
<tr class="separator:ga967a0564d6d59f2b9e12f4a5b7a3f877"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:gad1c7f891760e91301aac7e3a48aca449"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__FIR__Sparse.html#gad1c7f891760e91301aac7e3a48aca449">arm_fir_sparse_init_q15</a> (<a class="el" href="structarm__fir__sparse__instance__q15.html">arm_fir_sparse_instance_q15</a> *S, uint16_t numTaps, const <a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> *pCoeffs, <a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> *pState, int32_t *pTapDelay, uint16_t maxDelay, uint32_t <a class="el" href="arm__variance__example__f32_8c.html#ab6558f40a619c2502fbc24c880fd4fb0">blockSize</a>)</td></tr>
<tr class="memdesc:gad1c7f891760e91301aac7e3a48aca449"><td class="mdescLeft"> </td><td class="mdescRight">Initialization function for the Q15 sparse FIR filter. <a href="#gad1c7f891760e91301aac7e3a48aca449">More...</a><br/></td></tr>
<tr class="separator:gad1c7f891760e91301aac7e3a48aca449"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:gade71e2e0432a0e6de36fa9f23b2c984c"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__FIR__Sparse.html#gade71e2e0432a0e6de36fa9f23b2c984c">arm_fir_sparse_init_q31</a> (<a class="el" href="structarm__fir__sparse__instance__q31.html">arm_fir_sparse_instance_q31</a> *S, uint16_t numTaps, const <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> *pCoeffs, <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> *pState, int32_t *pTapDelay, uint16_t maxDelay, uint32_t <a class="el" href="arm__variance__example__f32_8c.html#ab6558f40a619c2502fbc24c880fd4fb0">blockSize</a>)</td></tr>
<tr class="memdesc:gade71e2e0432a0e6de36fa9f23b2c984c"><td class="mdescLeft"> </td><td class="mdescRight">Initialization function for the Q31 sparse FIR filter. <a href="#gade71e2e0432a0e6de36fa9f23b2c984c">More...</a><br/></td></tr>
<tr class="separator:gade71e2e0432a0e6de36fa9f23b2c984c"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:ga5e74f8f4e4df85de5feb4e62125ff590"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__FIR__Sparse.html#ga5e74f8f4e4df85de5feb4e62125ff590">arm_fir_sparse_init_q7</a> (<a class="el" href="structarm__fir__sparse__instance__q7.html">arm_fir_sparse_instance_q7</a> *S, uint16_t numTaps, const <a class="el" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263">q7_t</a> *pCoeffs, <a class="el" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263">q7_t</a> *pState, int32_t *pTapDelay, uint16_t maxDelay, uint32_t <a class="el" href="arm__variance__example__f32_8c.html#ab6558f40a619c2502fbc24c880fd4fb0">blockSize</a>)</td></tr>
<tr class="memdesc:ga5e74f8f4e4df85de5feb4e62125ff590"><td class="mdescLeft"> </td><td class="mdescRight">Initialization function for the Q7 sparse FIR filter. <a href="#ga5e74f8f4e4df85de5feb4e62125ff590">More...</a><br/></td></tr>
<tr class="separator:ga5e74f8f4e4df85de5feb4e62125ff590"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:gac3e43b06bff38ac8e62e145f88e9dbc7"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__FIR__Sparse.html#gac3e43b06bff38ac8e62e145f88e9dbc7">arm_fir_sparse_q15</a> (<a class="el" href="structarm__fir__sparse__instance__q15.html">arm_fir_sparse_instance_q15</a> *S, const <a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> *pSrc, <a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> *pDst, <a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> *pScratchIn, <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> *pScratchOut, uint32_t <a class="el" href="arm__variance__example__f32_8c.html#ab6558f40a619c2502fbc24c880fd4fb0">blockSize</a>)</td></tr>
<tr class="memdesc:gac3e43b06bff38ac8e62e145f88e9dbc7"><td class="mdescLeft"> </td><td class="mdescRight">Processing function for the Q15 sparse FIR filter. <a href="#gac3e43b06bff38ac8e62e145f88e9dbc7">More...</a><br/></td></tr>
<tr class="separator:gac3e43b06bff38ac8e62e145f88e9dbc7"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:gaba9f7ef4acf293034af42baa2fd3df52"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__FIR__Sparse.html#gaba9f7ef4acf293034af42baa2fd3df52">arm_fir_sparse_q31</a> (<a class="el" href="structarm__fir__sparse__instance__q31.html">arm_fir_sparse_instance_q31</a> *S, const <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> *pSrc, <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> *pDst, <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> *pScratchIn, uint32_t <a class="el" href="arm__variance__example__f32_8c.html#ab6558f40a619c2502fbc24c880fd4fb0">blockSize</a>)</td></tr>
<tr class="memdesc:gaba9f7ef4acf293034af42baa2fd3df52"><td class="mdescLeft"> </td><td class="mdescRight">Processing function for the Q31 sparse FIR filter. <a href="#gaba9f7ef4acf293034af42baa2fd3df52">More...</a><br/></td></tr>
<tr class="separator:gaba9f7ef4acf293034af42baa2fd3df52"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:ga319b3d9032ba723a8efb819b9d2a3676"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__FIR__Sparse.html#ga319b3d9032ba723a8efb819b9d2a3676">arm_fir_sparse_q7</a> (<a class="el" href="structarm__fir__sparse__instance__q7.html">arm_fir_sparse_instance_q7</a> *S, const <a class="el" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263">q7_t</a> *pSrc, <a class="el" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263">q7_t</a> *pDst, <a class="el" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263">q7_t</a> *pScratchIn, <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> *pScratchOut, uint32_t <a class="el" href="arm__variance__example__f32_8c.html#ab6558f40a619c2502fbc24c880fd4fb0">blockSize</a>)</td></tr>
<tr class="memdesc:ga319b3d9032ba723a8efb819b9d2a3676"><td class="mdescLeft"> </td><td class="mdescRight">Processing function for the Q7 sparse FIR filter. <a href="#ga319b3d9032ba723a8efb819b9d2a3676">More...</a><br/></td></tr>
<tr class="separator:ga319b3d9032ba723a8efb819b9d2a3676"><td class="memSeparator" colspan="2"> </td></tr>
</table>
<a name="details" id="details"></a><h2 class="groupheader">Description</h2>
<p>This group of functions implements sparse FIR filters. Sparse FIR filters are equivalent to standard FIR filters except that most of the coefficients are equal to zero. Sparse filters are used for simulating reflections in communications and audio applications.</p>
<p>There are separate functions for Q7, Q15, Q31, and floating-point data types. The functions operate on blocks of input and output data and each call to the function processes <code>blockSize</code> samples through the filter. <code>pSrc</code> and <code>pDst</code> points to input and output arrays respectively containing <code>blockSize</code> values.</p>
<dl class="section user"><dt>Algorithm</dt><dd>The sparse filter instant structure contains an array of tap indices <code>pTapDelay</code> which specifies the locations of the non-zero coefficients. This is in addition to the coefficient array <code>b</code>. The implementation essentially skips the multiplications by zero and leads to an efficient realization. <pre>
y[n] = b[0] * x[n-pTapDelay[0]] + b[1] * x[n-pTapDelay[1]] + b[2] * x[n-pTapDelay[2]] + ...+ b[numTaps-1] * x[n-pTapDelay[numTaps-1]]
</pre> </dd></dl>
<dl class="section user"><dt></dt><dd><div class="image">
<img src="FIRSparse.gif" alt="FIRSparse.gif"/>
<div class="caption">
Sparse FIR filter. b[n] represents the filter coefficients</div></div>
</dd></dl>
<dl class="section user"><dt></dt><dd><code>pCoeffs</code> points to a coefficient array of size <code>numTaps</code>; <code>pTapDelay</code> points to an array of nonzero indices and is also of size <code>numTaps</code>; <code>pState</code> points to a state array of size <code>maxDelay + blockSize</code>, where <code>maxDelay</code> is the largest offset value that is ever used in the <code>pTapDelay</code> array. Some of the processing functions also require temporary working buffers.</dd></dl>
<dl class="section user"><dt>Instance Structure</dt><dd>The coefficients and state variables for a filter are stored together in an instance data structure. A separate instance structure must be defined for each filter. Coefficient and offset arrays may be shared among several instances while state variable arrays cannot be shared. There are separate instance structure declarations for each of the 4 supported data types.</dd></dl>
<dl class="section user"><dt>Initialization Functions</dt><dd>There is also an associated initialization function for each data type. The initialization function performs the following operations:<ul>
<li>Sets the values of the internal structure fields.</li>
<li>Zeros out the values in the state buffer. To do this manually without calling the init function, assign the follow subfields of the instance structure: numTaps, pCoeffs, pTapDelay, maxDelay, stateIndex, pState. Also set all of the values in pState to zero. </li>
</ul>
</dd></dl>
<dl class="section user"><dt></dt><dd>Use of the initialization function is optional. However, if the initialization function is used, then the instance structure cannot be placed into a const data section. To place an instance structure into a const data section, the instance structure must be manually initialized. Set the values in the state buffer to zeros before static initialization. The code below statically initializes each of the 4 different data type filter instance structures <pre>
<a class="el" href="structarm__fir__sparse__instance__f32.html" title="Instance structure for the floating-point sparse FIR filter. ">arm_fir_sparse_instance_f32</a> S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay};
<a class="el" href="structarm__fir__sparse__instance__q31.html" title="Instance structure for the Q31 sparse FIR filter. ">arm_fir_sparse_instance_q31</a> S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay};
<a class="el" href="structarm__fir__sparse__instance__q15.html" title="Instance structure for the Q15 sparse FIR filter. ">arm_fir_sparse_instance_q15</a> S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay};
<a class="el" href="structarm__fir__sparse__instance__q7.html" title="Instance structure for the Q7 sparse FIR filter. ">arm_fir_sparse_instance_q7</a> S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay};
</pre></dd></dl>
<dl class="section user"><dt>Fixed-Point Behavior</dt><dd>Care must be taken when using the fixed-point versions of the sparse FIR filter functions. In particular, the overflow and saturation behavior of the accumulator used in each function must be considered. Refer to the function specific documentation below for usage guidelines. </dd></dl>
<h2 class="groupheader">Function Documentation</h2>
<a class="anchor" id="gac6817bc86974b7121c3288fce25dbc5f"></a>
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname">void arm_fir_sparse_f32 </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structarm__fir__sparse__instance__f32.html">arm_fir_sparse_instance_f32</a> * </td>
<td class="paramname"><em>S</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const <a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> * </td>
<td class="paramname"><em>pSrc</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> * </td>
<td class="paramname"><em>pDst</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> * </td>
<td class="paramname"><em>pScratchIn</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint32_t </td>
<td class="paramname"><em>blockSize</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
</tr>
</table>
</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramdir">[in]</td><td class="paramname">S</td><td>points to an instance of the floating-point sparse FIR structure </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pSrc</td><td>points to the block of input data </td></tr>
<tr><td class="paramdir">[out]</td><td class="paramname">pDst</td><td>points to the block of output data </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pScratchIn</td><td>points to a temporary buffer of size blockSize </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">blockSize</td><td>number of input samples to process </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>none </dd></dl>
</div>
</div>
<a class="anchor" id="ga967a0564d6d59f2b9e12f4a5b7a3f877"></a>
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname">void arm_fir_sparse_init_f32 </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structarm__fir__sparse__instance__f32.html">arm_fir_sparse_instance_f32</a> * </td>
<td class="paramname"><em>S</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint16_t </td>
<td class="paramname"><em>numTaps</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const <a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> * </td>
<td class="paramname"><em>pCoeffs</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> * </td>
<td class="paramname"><em>pState</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">int32_t * </td>
<td class="paramname"><em>pTapDelay</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint16_t </td>
<td class="paramname"><em>maxDelay</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint32_t </td>
<td class="paramname"><em>blockSize</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
</tr>
</table>
</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramdir">[in,out]</td><td class="paramname">S</td><td>points to an instance of the floating-point sparse FIR structure </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">numTaps</td><td>number of nonzero coefficients in the filter </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pCoeffs</td><td>points to the array of filter coefficients </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pState</td><td>points to the state buffer </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pTapDelay</td><td>points to the array of offset times </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">maxDelay</td><td>maximum offset time supported </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">blockSize</td><td>number of samples that will be processed per block </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>none</dd></dl>
<dl class="section user"><dt>Details</dt><dd><code>pCoeffs</code> holds the filter coefficients and has length <code>numTaps</code>. <code>pState</code> holds the filter's state variables and must be of length <code>maxDelay + blockSize</code>, where <code>maxDelay</code> is the maximum number of delay line values. <code>blockSize</code> is the number of samples processed by the <code><a class="el" href="group__FIR__Sparse.html#gac6817bc86974b7121c3288fce25dbc5f" title="Processing function for the floating-point sparse FIR filter. ">arm_fir_sparse_f32()</a></code> function. </dd></dl>
</div>
</div>
<a class="anchor" id="gad1c7f891760e91301aac7e3a48aca449"></a>
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname">void arm_fir_sparse_init_q15 </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structarm__fir__sparse__instance__q15.html">arm_fir_sparse_instance_q15</a> * </td>
<td class="paramname"><em>S</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint16_t </td>
<td class="paramname"><em>numTaps</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const <a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> * </td>
<td class="paramname"><em>pCoeffs</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> * </td>
<td class="paramname"><em>pState</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">int32_t * </td>
<td class="paramname"><em>pTapDelay</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint16_t </td>
<td class="paramname"><em>maxDelay</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint32_t </td>
<td class="paramname"><em>blockSize</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
</tr>
</table>
</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramdir">[in,out]</td><td class="paramname">S</td><td>points to an instance of the Q15 sparse FIR structure </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">numTaps</td><td>number of nonzero coefficients in the filter </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pCoeffs</td><td>points to the array of filter coefficients </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pState</td><td>points to the state buffer </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pTapDelay</td><td>points to the array of offset times </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">maxDelay</td><td>maximum offset time supported </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">blockSize</td><td>number of samples that will be processed per block </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>none</dd></dl>
<dl class="section user"><dt>Details</dt><dd><code>pCoeffs</code> holds the filter coefficients and has length <code>numTaps</code>. <code>pState</code> holds the filter's state variables and must be of length <code>maxDelay + blockSize</code>, where <code>maxDelay</code> is the maximum number of delay line values. <code>blockSize</code> is the number of words processed by <code><a class="el" href="group__FIR__Sparse.html#gac3e43b06bff38ac8e62e145f88e9dbc7" title="Processing function for the Q15 sparse FIR filter. ">arm_fir_sparse_q15()</a></code> function. </dd></dl>
</div>
</div>
<a class="anchor" id="gade71e2e0432a0e6de36fa9f23b2c984c"></a>
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname">void arm_fir_sparse_init_q31 </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structarm__fir__sparse__instance__q31.html">arm_fir_sparse_instance_q31</a> * </td>
<td class="paramname"><em>S</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint16_t </td>
<td class="paramname"><em>numTaps</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> * </td>
<td class="paramname"><em>pCoeffs</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> * </td>
<td class="paramname"><em>pState</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">int32_t * </td>
<td class="paramname"><em>pTapDelay</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint16_t </td>
<td class="paramname"><em>maxDelay</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint32_t </td>
<td class="paramname"><em>blockSize</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
</tr>
</table>
</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramdir">[in,out]</td><td class="paramname">S</td><td>points to an instance of the Q31 sparse FIR structure </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">numTaps</td><td>number of nonzero coefficients in the filter </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pCoeffs</td><td>points to the array of filter coefficients </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pState</td><td>points to the state buffer </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pTapDelay</td><td>points to the array of offset times </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">maxDelay</td><td>maximum offset time supported </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">blockSize</td><td>number of samples that will be processed per block </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>none</dd></dl>
<dl class="section user"><dt>Details</dt><dd><code>pCoeffs</code> holds the filter coefficients and has length <code>numTaps</code>. <code>pState</code> holds the filter's state variables and must be of length <code>maxDelay + blockSize</code>, where <code>maxDelay</code> is the maximum number of delay line values. <code>blockSize</code> is the number of words processed by <code><a class="el" href="group__FIR__Sparse.html#gaba9f7ef4acf293034af42baa2fd3df52" title="Processing function for the Q31 sparse FIR filter. ">arm_fir_sparse_q31()</a></code> function. </dd></dl>
</div>
</div>
<a class="anchor" id="ga5e74f8f4e4df85de5feb4e62125ff590"></a>
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname">void arm_fir_sparse_init_q7 </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structarm__fir__sparse__instance__q7.html">arm_fir_sparse_instance_q7</a> * </td>
<td class="paramname"><em>S</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint16_t </td>
<td class="paramname"><em>numTaps</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const <a class="el" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263">q7_t</a> * </td>
<td class="paramname"><em>pCoeffs</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263">q7_t</a> * </td>
<td class="paramname"><em>pState</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">int32_t * </td>
<td class="paramname"><em>pTapDelay</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint16_t </td>
<td class="paramname"><em>maxDelay</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint32_t </td>
<td class="paramname"><em>blockSize</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
</tr>
</table>
</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramdir">[in,out]</td><td class="paramname">S</td><td>points to an instance of the Q7 sparse FIR structure </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">numTaps</td><td>number of nonzero coefficients in the filter </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pCoeffs</td><td>points to the array of filter coefficients </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pState</td><td>points to the state buffer </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pTapDelay</td><td>points to the array of offset times </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">maxDelay</td><td>maximum offset time supported </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">blockSize</td><td>number of samples that will be processed per block </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>none</dd></dl>
<dl class="section user"><dt>Details</dt><dd><code>pCoeffs</code> holds the filter coefficients and has length <code>numTaps</code>. <code>pState</code> holds the filter's state variables and must be of length <code>maxDelay + blockSize</code>, where <code>maxDelay</code> is the maximum number of delay line values. <code>blockSize</code> is the number of samples processed by the <code><a class="el" href="group__FIR__Sparse.html#ga319b3d9032ba723a8efb819b9d2a3676" title="Processing function for the Q7 sparse FIR filter. ">arm_fir_sparse_q7()</a></code> function. </dd></dl>
</div>
</div>
<a class="anchor" id="gac3e43b06bff38ac8e62e145f88e9dbc7"></a>
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname">void arm_fir_sparse_q15 </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structarm__fir__sparse__instance__q15.html">arm_fir_sparse_instance_q15</a> * </td>
<td class="paramname"><em>S</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const <a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> * </td>
<td class="paramname"><em>pSrc</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> * </td>
<td class="paramname"><em>pDst</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> * </td>
<td class="paramname"><em>pScratchIn</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> * </td>
<td class="paramname"><em>pScratchOut</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint32_t </td>
<td class="paramname"><em>blockSize</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
</tr>
</table>
</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramdir">[in]</td><td class="paramname">S</td><td>points to an instance of the Q15 sparse FIR structure </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pSrc</td><td>points to the block of input data </td></tr>
<tr><td class="paramdir">[out]</td><td class="paramname">pDst</td><td>points to the block of output data </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pScratchIn</td><td>points to a temporary buffer of size blockSize </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pScratchOut</td><td>points to a temporary buffer of size blockSize </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">blockSize</td><td>number of input samples to process per call </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>none</dd></dl>
<dl class="section user"><dt>Scaling and Overflow Behavior</dt><dd>The function is implemented using an internal 32-bit accumulator. The 1.15 x 1.15 multiplications yield a 2.30 result and these are added to a 2.30 accumulator. Thus the full precision of the multiplications is maintained but there is only a single guard bit in the accumulator. If the accumulator result overflows it will wrap around rather than saturate. After all multiply-accumulates are performed, the 2.30 accumulator is truncated to 2.15 format and then saturated to 1.15 format. In order to avoid overflows the input signal or coefficients must be scaled down by log2(numTaps) bits. </dd></dl>
</div>
</div>
<a class="anchor" id="gaba9f7ef4acf293034af42baa2fd3df52"></a>
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname">void arm_fir_sparse_q31 </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structarm__fir__sparse__instance__q31.html">arm_fir_sparse_instance_q31</a> * </td>
<td class="paramname"><em>S</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> * </td>
<td class="paramname"><em>pSrc</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> * </td>
<td class="paramname"><em>pDst</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> * </td>
<td class="paramname"><em>pScratchIn</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint32_t </td>
<td class="paramname"><em>blockSize</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
</tr>
</table>
</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramdir">[in]</td><td class="paramname">S</td><td>points to an instance of the Q31 sparse FIR structure </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pSrc</td><td>points to the block of input data </td></tr>
<tr><td class="paramdir">[out]</td><td class="paramname">pDst</td><td>points to the block of output data </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pScratchIn</td><td>points to a temporary buffer of size blockSize </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">blockSize</td><td>number of input samples to process </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>none</dd></dl>
<dl class="section user"><dt>Scaling and Overflow Behavior</dt><dd>The function is implemented using an internal 32-bit accumulator. The 1.31 x 1.31 multiplications are truncated to 2.30 format. This leads to loss of precision on the intermediate multiplications and provides only a single guard bit. If the accumulator result overflows, it wraps around rather than saturate. In order to avoid overflows the input signal or coefficients must be scaled down by log2(numTaps) bits. </dd></dl>
</div>
</div>
<a class="anchor" id="ga319b3d9032ba723a8efb819b9d2a3676"></a>
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname">void arm_fir_sparse_q7 </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structarm__fir__sparse__instance__q7.html">arm_fir_sparse_instance_q7</a> * </td>
<td class="paramname"><em>S</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const <a class="el" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263">q7_t</a> * </td>
<td class="paramname"><em>pSrc</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263">q7_t</a> * </td>
<td class="paramname"><em>pDst</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263">q7_t</a> * </td>
<td class="paramname"><em>pScratchIn</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> * </td>
<td class="paramname"><em>pScratchOut</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint32_t </td>
<td class="paramname"><em>blockSize</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
</tr>
</table>
</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramdir">[in]</td><td class="paramname">S</td><td>points to an instance of the Q7 sparse FIR structure </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pSrc</td><td>points to the block of input data </td></tr>
<tr><td class="paramdir">[out]</td><td class="paramname">pDst</td><td>points to the block of output data </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pScratchIn</td><td>points to a temporary buffer of size blockSize </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">pScratchOut</td><td>points to a temporary buffer of size blockSize </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">blockSize</td><td>number of input samples to process </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>none</dd></dl>
<dl class="section user"><dt>Scaling and Overflow Behavior</dt><dd>The function is implemented using a 32-bit internal accumulator. Both coefficients and state variables are represented in 1.7 format and multiplications yield a 2.14 result. The 2.14 intermediate results are accumulated in a 32-bit accumulator in 18.14 format. There is no risk of internal overflow with this approach and the full precision of intermediate multiplications is preserved. The accumulator is then converted to 18.7 format by discarding the low 7 bits. Finally, the result is truncated to 1.7 format. </dd></dl>
</div>
</div>
</div><!-- contents -->
</div><!-- doc-content -->
<!-- start footer part -->
<div id="nav-path" class="navpath"><!-- id is needed for treeview function! -->
<ul>
<li class="footer">Generated on Wed Jul 10 2019 15:20:40 for CMSIS-DSP Version 1.7.0 by Arm Ltd. All rights reserved.
<!--
<a href="http://www.doxygen.org/index.html">
<img class="footer" src="doxygen.png" alt="doxygen"/></a> 1.8.6
-->
</li>
</ul>
</div>
</body>
</html>
|
