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49 <div class="headertitle">
50 <h1>arm_fir_fast_q15.c</h1> </div>
52 <div class="contents">
53 <a href="arm__fir__fast__q15_8c.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/* ---------------------------------------------------------------------- </span>
54 <a name="l00002"></a>00002 <span class="comment">* Copyright (C) 2010 ARM Limited. All rights reserved. </span>
55 <a name="l00003"></a>00003 <span class="comment">* </span>
56 <a name="l00004"></a>00004 <span class="comment">* $Date: 15. July 2011 </span>
57 <a name="l00005"></a>00005 <span class="comment">* $Revision: V1.0.10 </span>
58 <a name="l00006"></a>00006 <span class="comment">* </span>
59 <a name="l00007"></a>00007 <span class="comment">* Project: CMSIS DSP Library </span>
60 <a name="l00008"></a>00008 <span class="comment">* Title: arm_fir_fast_q15.c </span>
61 <a name="l00009"></a>00009 <span class="comment">* </span>
62 <a name="l00010"></a>00010 <span class="comment">* Description: Q15 Fast FIR filter processing function. </span>
63 <a name="l00011"></a>00011 <span class="comment">* </span>
64 <a name="l00012"></a>00012 <span class="comment">* Target Processor: Cortex-M4/Cortex-M3</span>
65 <a name="l00013"></a>00013 <span class="comment">* </span>
66 <a name="l00014"></a>00014 <span class="comment">* Version 1.0.10 2011/7/15 </span>
67 <a name="l00015"></a>00015 <span class="comment">* Big Endian support added and Merged M0 and M3/M4 Source code. </span>
68 <a name="l00016"></a>00016 <span class="comment">* </span>
69 <a name="l00017"></a>00017 <span class="comment">* Version 1.0.3 2010/11/29 </span>
70 <a name="l00018"></a>00018 <span class="comment">* Re-organized the CMSIS folders and updated documentation. </span>
71 <a name="l00019"></a>00019 <span class="comment">* </span>
72 <a name="l00020"></a>00020 <span class="comment">* Version 1.0.2 2010/11/11 </span>
73 <a name="l00021"></a>00021 <span class="comment">* Documentation updated. </span>
74 <a name="l00022"></a>00022 <span class="comment">* </span>
75 <a name="l00023"></a>00023 <span class="comment">* Version 1.0.1 2010/10/05 </span>
76 <a name="l00024"></a>00024 <span class="comment">* Production release and review comments incorporated. </span>
77 <a name="l00025"></a>00025 <span class="comment">* </span>
78 <a name="l00026"></a>00026 <span class="comment">* Version 1.0.0 2010/09/20 </span>
79 <a name="l00027"></a>00027 <span class="comment">* Production release and review comments incorporated. </span>
80 <a name="l00028"></a>00028 <span class="comment">* </span>
81 <a name="l00029"></a>00029 <span class="comment">* Version 0.0.9 2010/08/16 </span>
82 <a name="l00030"></a>00030 <span class="comment">* Initial version </span>
83 <a name="l00031"></a>00031 <span class="comment">* </span>
84 <a name="l00032"></a>00032 <span class="comment">* -------------------------------------------------------------------- */</span>
85 <a name="l00033"></a>00033
86 <a name="l00034"></a>00034 <span class="preprocessor">#include "<a class="code" href="arm__math_8h.html">arm_math.h</a>"</span>
87 <a name="l00035"></a>00035
88 <a name="l00065"></a><a class="code" href="group___f_i_r.html#gac7d35e9472e49ccd88800f37f3476bd3">00065</a> <span class="keywordtype">void</span> <a class="code" href="group___f_i_r.html#gac7d35e9472e49ccd88800f37f3476bd3" title="Processing function for the fast Q15 FIR filter for Cortex-M3 and Cortex-M4.">arm_fir_fast_q15</a>(
89 <a name="l00066"></a>00066 <span class="keyword">const</span> <a class="code" href="structarm__fir__instance__q15.html" title="Instance structure for the Q15 FIR filter.">arm_fir_instance_q15</a> * S,
90 <a name="l00067"></a>00067 <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> * pSrc,
91 <a name="l00068"></a>00068 <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> * pDst,
92 <a name="l00069"></a>00069 uint32_t <a class="code" href="arm__fir__example__f32_8c.html#ab6558f40a619c2502fbc24c880fd4fb0">blockSize</a>)
93 <a name="l00070"></a>00070 {
94 <a name="l00071"></a>00071 <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> *pState = S-><a class="code" href="structarm__fir__instance__q15.html#aa8d25f44f45b6a6c4cf38c31569b8a01">pState</a>; <span class="comment">/* State pointer */</span>
95 <a name="l00072"></a>00072 <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> *pCoeffs = S-><a class="code" href="structarm__fir__instance__q15.html#a6d16db16a5f8f0db54938f2967244d9e">pCoeffs</a>; <span class="comment">/* Coefficient pointer */</span>
96 <a name="l00073"></a>00073 <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> *pStateCurnt; <span class="comment">/* Points to the current sample of the state */</span>
97 <a name="l00074"></a>00074 <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> *px1; <span class="comment">/* Temporary q15 pointer for state buffer */</span>
98 <a name="l00075"></a>00075 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *pb; <span class="comment">/* Temporary pointer for coefficient buffer */</span>
99 <a name="l00076"></a>00076 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *px2; <span class="comment">/* Temporary q31 pointer for SIMD state buffer accesses */</span>
100 <a name="l00077"></a>00077 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> x0, x1, x2, x3, c0; <span class="comment">/* Temporary variables to hold SIMD state and coefficient values */</span>
101 <a name="l00078"></a>00078 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> acc0, acc1, acc2, acc3; <span class="comment">/* Accumulators */</span>
102 <a name="l00079"></a>00079 uint32_t numTaps = S-><a class="code" href="structarm__fir__instance__q15.html#a0e46f93cf51bfb18b1be808be9c5bfc9">numTaps</a>; <span class="comment">/* Number of taps in the filter */</span>
103 <a name="l00080"></a>00080 uint32_t tapCnt, blkCnt; <span class="comment">/* Loop counters */</span>
104 <a name="l00081"></a>00081
105 <a name="l00082"></a>00082 <span class="comment">/* S->pState points to buffer which contains previous frame (numTaps - 1) samples */</span>
106 <a name="l00083"></a>00083 <span class="comment">/* pStateCurnt points to the location where the new input data should be written */</span>
107 <a name="l00084"></a>00084 pStateCurnt = &(S-><a class="code" href="structarm__fir__instance__q15.html#aa8d25f44f45b6a6c4cf38c31569b8a01">pState</a>[(numTaps - 1u)]);
108 <a name="l00085"></a>00085
109 <a name="l00086"></a>00086 <span class="comment">/* Apply loop unrolling and compute 4 output values simultaneously. </span>
110 <a name="l00087"></a>00087 <span class="comment"> * The variables acc0 ... acc3 hold output values that are being computed: </span>
111 <a name="l00088"></a>00088 <span class="comment"> * </span>
112 <a name="l00089"></a>00089 <span class="comment"> * acc0 = b[numTaps-1] * x[n-numTaps-1] + b[numTaps-2] * x[n-numTaps-2] + b[numTaps-3] * x[n-numTaps-3] +...+ b[0] * x[0] </span>
113 <a name="l00090"></a>00090 <span class="comment"> * acc1 = b[numTaps-1] * x[n-numTaps] + b[numTaps-2] * x[n-numTaps-1] + b[numTaps-3] * x[n-numTaps-2] +...+ b[0] * x[1] </span>
114 <a name="l00091"></a>00091 <span class="comment"> * acc2 = b[numTaps-1] * x[n-numTaps+1] + b[numTaps-2] * x[n-numTaps] + b[numTaps-3] * x[n-numTaps-1] +...+ b[0] * x[2] </span>
115 <a name="l00092"></a>00092 <span class="comment"> * acc3 = b[numTaps-1] * x[n-numTaps+2] + b[numTaps-2] * x[n-numTaps+1] + b[numTaps-3] * x[n-numTaps] +...+ b[0] * x[3] </span>
116 <a name="l00093"></a>00093 <span class="comment"> */</span>
117 <a name="l00094"></a>00094 blkCnt = blockSize >> 2;
118 <a name="l00095"></a>00095
119 <a name="l00096"></a>00096 <span class="comment">/* First part of the processing with loop unrolling. Compute 4 outputs at a time. </span>
120 <a name="l00097"></a>00097 <span class="comment"> ** a second loop below computes the remaining 1 to 3 samples. */</span>
121 <a name="l00098"></a>00098 <span class="keywordflow">while</span>(blkCnt > 0u)
122 <a name="l00099"></a>00099 {
123 <a name="l00100"></a>00100 <span class="comment">/* Copy four new input samples into the state buffer. </span>
124 <a name="l00101"></a>00101 <span class="comment"> ** Use 32-bit SIMD to move the 16-bit data. Only requires two copies. */</span>
125 <a name="l00102"></a>00102 *<a class="code" href="arm__math_8h.html#a9de2e0a5785be82866bcb96012282248" title="definition to read/write two 16 bit values.">__SIMD32</a>(pStateCurnt)++ = *<a class="code" href="arm__math_8h.html#a9de2e0a5785be82866bcb96012282248" title="definition to read/write two 16 bit values.">__SIMD32</a>(pSrc)++;
126 <a name="l00103"></a>00103 *<a class="code" href="arm__math_8h.html#a9de2e0a5785be82866bcb96012282248" title="definition to read/write two 16 bit values.">__SIMD32</a>(pStateCurnt)++ = *<a class="code" href="arm__math_8h.html#a9de2e0a5785be82866bcb96012282248" title="definition to read/write two 16 bit values.">__SIMD32</a>(pSrc)++;
127 <a name="l00104"></a>00104
128 <a name="l00105"></a>00105 <span class="comment">/* Set all accumulators to zero */</span>
129 <a name="l00106"></a>00106 acc0 = 0;
130 <a name="l00107"></a>00107 acc1 = 0;
131 <a name="l00108"></a>00108 acc2 = 0;
132 <a name="l00109"></a>00109 acc3 = 0;
133 <a name="l00110"></a>00110
134 <a name="l00111"></a>00111 <span class="comment">/* Initialize state pointer of type q15 */</span>
135 <a name="l00112"></a>00112 px1 = pState;
136 <a name="l00113"></a>00113
137 <a name="l00114"></a>00114 <span class="comment">/* Initialize coeff pointer of type q31 */</span>
138 <a name="l00115"></a>00115 pb = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *) (pCoeffs);
139 <a name="l00116"></a>00116
140 <a name="l00117"></a>00117 <span class="comment">/* Read the first two samples from the state buffer: x[n-N], x[n-N-1] */</span>
141 <a name="l00118"></a>00118 x0 = *(<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *) (px1++);
142 <a name="l00119"></a>00119
143 <a name="l00120"></a>00120 <span class="comment">/* Read the third and forth samples from the state buffer: x[n-N-1], x[n-N-2] */</span>
144 <a name="l00121"></a>00121 x1 = *(<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *) (px1++);
145 <a name="l00122"></a>00122
146 <a name="l00123"></a>00123 <span class="comment">/* Loop over the number of taps. Unroll by a factor of 4. </span>
147 <a name="l00124"></a>00124 <span class="comment"> ** Repeat until we've computed numTaps-4 coefficients. */</span>
148 <a name="l00125"></a>00125 tapCnt = numTaps >> 2;
149 <a name="l00126"></a>00126 <span class="keywordflow">do</span>
150 <a name="l00127"></a>00127 {
151 <a name="l00128"></a>00128 <span class="comment">/* Read the first two coefficients using SIMD: b[N] and b[N-1] coefficients */</span>
152 <a name="l00129"></a>00129 c0 = *(pb++);
153 <a name="l00130"></a>00130
154 <a name="l00131"></a>00131 <span class="comment">/* acc0 += b[N] * x[n-N] + b[N-1] * x[n-N-1] */</span>
155 <a name="l00132"></a>00132 acc0 = __SMLAD(x0, c0, acc0);
156 <a name="l00133"></a>00133
157 <a name="l00134"></a>00134 <span class="comment">/* acc1 += b[N] * x[n-N-1] + b[N-1] * x[n-N-2] */</span>
158 <a name="l00135"></a>00135 acc1 = __SMLAD(x1, c0, acc1);
159 <a name="l00136"></a>00136
160 <a name="l00137"></a>00137 <span class="comment">/* Read state x[n-N-2], x[n-N-3] */</span>
161 <a name="l00138"></a>00138 x2 = *(<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *) (px1++);
162 <a name="l00139"></a>00139
163 <a name="l00140"></a>00140 <span class="comment">/* Read state x[n-N-3], x[n-N-4] */</span>
164 <a name="l00141"></a>00141 x3 = *(<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *) (px1++);
165 <a name="l00142"></a>00142
166 <a name="l00143"></a>00143 <span class="comment">/* acc2 += b[N] * x[n-N-2] + b[N-1] * x[n-N-3] */</span>
167 <a name="l00144"></a>00144 acc2 = __SMLAD(x2, c0, acc2);
168 <a name="l00145"></a>00145
169 <a name="l00146"></a>00146 <span class="comment">/* acc3 += b[N] * x[n-N-3] + b[N-1] * x[n-N-4] */</span>
170 <a name="l00147"></a>00147 acc3 = __SMLAD(x3, c0, acc3);
171 <a name="l00148"></a>00148
172 <a name="l00149"></a>00149 <span class="comment">/* Read coefficients b[N-2], b[N-3] */</span>
173 <a name="l00150"></a>00150 c0 = *(pb++);
174 <a name="l00151"></a>00151
175 <a name="l00152"></a>00152 <span class="comment">/* acc0 += b[N-2] * x[n-N-2] + b[N-3] * x[n-N-3] */</span>
176 <a name="l00153"></a>00153 acc0 = __SMLAD(x2, c0, acc0);
177 <a name="l00154"></a>00154
178 <a name="l00155"></a>00155 <span class="comment">/* acc1 += b[N-2] * x[n-N-3] + b[N-3] * x[n-N-4] */</span>
179 <a name="l00156"></a>00156 acc1 = __SMLAD(x3, c0, acc1);
180 <a name="l00157"></a>00157
181 <a name="l00158"></a>00158 <span class="comment">/* Read state x[n-N-4], x[n-N-5] */</span>
182 <a name="l00159"></a>00159 x0 = *(<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *) (px1++);
183 <a name="l00160"></a>00160
184 <a name="l00161"></a>00161 <span class="comment">/* Read state x[n-N-5], x[n-N-6] */</span>
185 <a name="l00162"></a>00162 x1 = *(<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *) (px1++);
186 <a name="l00163"></a>00163
187 <a name="l00164"></a>00164 <span class="comment">/* acc2 += b[N-2] * x[n-N-4] + b[N-3] * x[n-N-5] */</span>
188 <a name="l00165"></a>00165 acc2 = __SMLAD(x0, c0, acc2);
189 <a name="l00166"></a>00166
190 <a name="l00167"></a>00167 <span class="comment">/* acc3 += b[N-2] * x[n-N-5] + b[N-3] * x[n-N-6] */</span>
191 <a name="l00168"></a>00168 acc3 = __SMLAD(x1, c0, acc3);
192 <a name="l00169"></a>00169 tapCnt--;
193 <a name="l00170"></a>00170
194 <a name="l00171"></a>00171 }
195 <a name="l00172"></a>00172 <span class="keywordflow">while</span>(tapCnt > 0u);
196 <a name="l00173"></a>00173
197 <a name="l00174"></a>00174 <span class="comment">/* If the filter length is not a multiple of 4, compute the remaining filter taps. </span>
198 <a name="l00175"></a>00175 <span class="comment"> ** This is always 2 taps since the filter length is always even. */</span>
199 <a name="l00176"></a>00176 <span class="keywordflow">if</span>((numTaps & 0x3u) != 0u)
200 <a name="l00177"></a>00177 {
201 <a name="l00178"></a>00178 <span class="comment">/* Read 2 coefficients */</span>
202 <a name="l00179"></a>00179 c0 = *(pb++);
203 <a name="l00180"></a>00180 <span class="comment">/* Fetch 4 state variables */</span>
204 <a name="l00181"></a>00181 x2 = *(<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *) (px1++);
205 <a name="l00182"></a>00182 x3 = *(<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *) (px1++);
206 <a name="l00183"></a>00183
207 <a name="l00184"></a>00184 <span class="comment">/* Perform the multiply-accumulates */</span>
208 <a name="l00185"></a>00185 acc0 = __SMLAD(x0, c0, acc0);
209 <a name="l00186"></a>00186 acc1 = __SMLAD(x1, c0, acc1);
210 <a name="l00187"></a>00187 acc2 = __SMLAD(x2, c0, acc2);
211 <a name="l00188"></a>00188 acc3 = __SMLAD(x3, c0, acc3);
212 <a name="l00189"></a>00189 }
213 <a name="l00190"></a>00190
214 <a name="l00191"></a>00191 <span class="comment">/* The results in the 4 accumulators are in 2.30 format. Convert to 1.15 with saturation. </span>
215 <a name="l00192"></a>00192 <span class="comment"> ** Then store the 4 outputs in the destination buffer. */</span>
216 <a name="l00193"></a>00193
217 <a name="l00194"></a>00194 <span class="preprocessor">#ifndef ARM_MATH_BIG_ENDIAN</span>
218 <a name="l00195"></a>00195 <span class="preprocessor"></span>
219 <a name="l00196"></a>00196 *<a class="code" href="arm__math_8h.html#a9de2e0a5785be82866bcb96012282248" title="definition to read/write two 16 bit values.">__SIMD32</a>(pDst)++ = __PKHBT((acc0 >> 15), (acc1 >> 15), 16u);
220 <a name="l00197"></a>00197 *<a class="code" href="arm__math_8h.html#a9de2e0a5785be82866bcb96012282248" title="definition to read/write two 16 bit values.">__SIMD32</a>(pDst)++ = __PKHBT((acc2 >> 15), (acc3 >> 15), 16u);
221 <a name="l00198"></a>00198
222 <a name="l00199"></a>00199 <span class="preprocessor">#else</span>
223 <a name="l00200"></a>00200 <span class="preprocessor"></span>
224 <a name="l00201"></a>00201 *<a class="code" href="arm__math_8h.html#a9de2e0a5785be82866bcb96012282248" title="definition to read/write two 16 bit values.">__SIMD32</a>(pDst)++ = __PKHBT((acc1 >> 15), (acc0 >> 15), 16u);
225 <a name="l00202"></a>00202 *<a class="code" href="arm__math_8h.html#a9de2e0a5785be82866bcb96012282248" title="definition to read/write two 16 bit values.">__SIMD32</a>(pDst)++ = __PKHBT((acc3 >> 15), (acc2 >> 15), 16u);
226 <a name="l00203"></a>00203
227 <a name="l00204"></a>00204 <span class="preprocessor">#endif </span><span class="comment">/* #ifndef ARM_MATH_BIG_ENDIAN */</span>
228 <a name="l00205"></a>00205
229 <a name="l00206"></a>00206 <span class="comment">/* Advance the state pointer by 4 to process the next group of 4 samples */</span>
230 <a name="l00207"></a>00207 pState = pState + 4;
231 <a name="l00208"></a>00208
232 <a name="l00209"></a>00209 <span class="comment">/* Decrement the loop counter */</span>
233 <a name="l00210"></a>00210 blkCnt--;
234 <a name="l00211"></a>00211 }
235 <a name="l00212"></a>00212
236 <a name="l00213"></a>00213 <span class="comment">/* If the blockSize is not a multiple of 4, compute any remaining output samples here. </span>
237 <a name="l00214"></a>00214 <span class="comment"> ** No loop unrolling is used. */</span>
238 <a name="l00215"></a>00215 blkCnt = blockSize % 0x4u;
239 <a name="l00216"></a>00216 <span class="keywordflow">while</span>(blkCnt > 0u)
240 <a name="l00217"></a>00217 {
241 <a name="l00218"></a>00218 <span class="comment">/* Copy two samples into state buffer */</span>
242 <a name="l00219"></a>00219 *pStateCurnt++ = *pSrc++;
243 <a name="l00220"></a>00220
244 <a name="l00221"></a>00221 <span class="comment">/* Set the accumulator to zero */</span>
245 <a name="l00222"></a>00222 acc0 = 0;
246 <a name="l00223"></a>00223
247 <a name="l00224"></a>00224 <span class="comment">/* Use SIMD to hold states and coefficients */</span>
248 <a name="l00225"></a>00225 px2 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *) pState;
249 <a name="l00226"></a>00226 pb = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *) (pCoeffs);
250 <a name="l00227"></a>00227 tapCnt = numTaps >> 1;
251 <a name="l00228"></a>00228
252 <a name="l00229"></a>00229 <span class="keywordflow">do</span>
253 <a name="l00230"></a>00230 {
254 <a name="l00231"></a>00231 acc0 = __SMLAD(*px2++, *(pb++), acc0);
255 <a name="l00232"></a>00232 tapCnt--;
256 <a name="l00233"></a>00233 }
257 <a name="l00234"></a>00234 <span class="keywordflow">while</span>(tapCnt > 0u);
258 <a name="l00235"></a>00235
259 <a name="l00236"></a>00236 <span class="comment">/* The result is in 2.30 format. Convert to 1.15 with saturation. </span>
260 <a name="l00237"></a>00237 <span class="comment"> ** Then store the output in the destination buffer. */</span>
261 <a name="l00238"></a>00238 *pDst++ = (<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) ((acc0 >> 15));
262 <a name="l00239"></a>00239
263 <a name="l00240"></a>00240 <span class="comment">/* Advance state pointer by 1 for the next sample */</span>
264 <a name="l00241"></a>00241 pState = pState + 1;
265 <a name="l00242"></a>00242
266 <a name="l00243"></a>00243 <span class="comment">/* Decrement the loop counter */</span>
267 <a name="l00244"></a>00244 blkCnt--;
268 <a name="l00245"></a>00245 }
269 <a name="l00246"></a>00246
270 <a name="l00247"></a>00247 <span class="comment">/* Processing is complete. </span>
271 <a name="l00248"></a>00248 <span class="comment"> ** Now copy the last numTaps - 1 samples to the satrt of the state buffer. </span>
272 <a name="l00249"></a>00249 <span class="comment"> ** This prepares the state buffer for the next function call. */</span>
273 <a name="l00250"></a>00250
274 <a name="l00251"></a>00251 <span class="comment">/* Points to the start of the state buffer */</span>
275 <a name="l00252"></a>00252 pStateCurnt = S-><a class="code" href="structarm__fir__instance__q15.html#aa8d25f44f45b6a6c4cf38c31569b8a01">pState</a>;
276 <a name="l00253"></a>00253 <span class="comment">/* Calculation of count for copying integer writes */</span>
277 <a name="l00254"></a>00254 tapCnt = (numTaps - 1u) >> 2;
278 <a name="l00255"></a>00255
279 <a name="l00256"></a>00256 <span class="keywordflow">while</span>(tapCnt > 0u)
280 <a name="l00257"></a>00257 {
281 <a name="l00258"></a>00258 *<a class="code" href="arm__math_8h.html#a9de2e0a5785be82866bcb96012282248" title="definition to read/write two 16 bit values.">__SIMD32</a>(pStateCurnt)++ = *<a class="code" href="arm__math_8h.html#a9de2e0a5785be82866bcb96012282248" title="definition to read/write two 16 bit values.">__SIMD32</a>(pState)++;
282 <a name="l00259"></a>00259 *<a class="code" href="arm__math_8h.html#a9de2e0a5785be82866bcb96012282248" title="definition to read/write two 16 bit values.">__SIMD32</a>(pStateCurnt)++ = *<a class="code" href="arm__math_8h.html#a9de2e0a5785be82866bcb96012282248" title="definition to read/write two 16 bit values.">__SIMD32</a>(pState)++;
283 <a name="l00260"></a>00260
284 <a name="l00261"></a>00261 tapCnt--;
285 <a name="l00262"></a>00262 }
286 <a name="l00263"></a>00263
287 <a name="l00264"></a>00264 <span class="comment">/* Calculation of count for remaining q15_t data */</span>
288 <a name="l00265"></a>00265 tapCnt = (numTaps - 1u) % 0x4u;
289 <a name="l00266"></a>00266
290 <a name="l00267"></a>00267 <span class="comment">/* copy remaining data */</span>
291 <a name="l00268"></a>00268 <span class="keywordflow">while</span>(tapCnt > 0u)
292 <a name="l00269"></a>00269 {
293 <a name="l00270"></a>00270 *pStateCurnt++ = *pState++;
294 <a name="l00271"></a>00271
295 <a name="l00272"></a>00272 <span class="comment">/* Decrement the loop counter */</span>
296 <a name="l00273"></a>00273 tapCnt--;
297 <a name="l00274"></a>00274 }
298 <a name="l00275"></a>00275 }
299 <a name="l00276"></a>00276
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