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49 <div class="headertitle">
50 <h1>arm_fir_q7.c</h1> </div>
52 <div class="contents">
53 <a href="arm__fir__q7_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_q7.c </span>
61 <a name="l00009"></a>00009 <span class="comment">* </span>
62 <a name="l00010"></a>00010 <span class="comment">* Description: Q7 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/Cortex-M0</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 0.0.5 2010/04/26 </span>
82 <a name="l00030"></a>00030 <span class="comment">* incorporated review comments and updated with latest CMSIS layer </span>
83 <a name="l00031"></a>00031 <span class="comment">* </span>
84 <a name="l00032"></a>00032 <span class="comment">* Version 0.0.3 2010/03/10 </span>
85 <a name="l00033"></a>00033 <span class="comment">* Initial version </span>
86 <a name="l00034"></a>00034 <span class="comment">* -------------------------------------------------------------------- */</span>
87 <a name="l00035"></a>00035
88 <a name="l00036"></a>00036 <span class="preprocessor">#include "<a class="code" href="arm__math_8h.html">arm_math.h</a>"</span>
89 <a name="l00037"></a>00037
90 <a name="l00064"></a><a class="code" href="group___f_i_r.html#ga31c91a0bf0962327ef8f626fae68ea32">00064</a> <span class="keywordtype">void</span> <a class="code" href="group___f_i_r.html#ga31c91a0bf0962327ef8f626fae68ea32" title="Processing function for the Q7 FIR filter.">arm_fir_q7</a>(
91 <a name="l00065"></a>00065 <span class="keyword">const</span> <a class="code" href="structarm__fir__instance__q7.html" title="Instance structure for the Q7 FIR filter.">arm_fir_instance_q7</a> * S,
92 <a name="l00066"></a>00066 <a class="code" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263" title="8-bit fractional data type in 1.7 format.">q7_t</a> * pSrc,
93 <a name="l00067"></a>00067 <a class="code" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263" title="8-bit fractional data type in 1.7 format.">q7_t</a> * pDst,
94 <a name="l00068"></a>00068 uint32_t <a class="code" href="arm__fir__example__f32_8c.html#ab6558f40a619c2502fbc24c880fd4fb0">blockSize</a>)
95 <a name="l00069"></a>00069 {
96 <a name="l00070"></a>00070
97 <a name="l00071"></a>00071 <span class="preprocessor">#ifndef ARM_MATH_CM0</span>
98 <a name="l00072"></a>00072 <span class="preprocessor"></span>
99 <a name="l00073"></a>00073 <span class="comment">/* Run the below code for Cortex-M4 and Cortex-M3 */</span>
100 <a name="l00074"></a>00074
101 <a name="l00075"></a>00075 <a class="code" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263" title="8-bit fractional data type in 1.7 format.">q7_t</a> *pState = S-><a class="code" href="structarm__fir__instance__q7.html#aaddea3b9c7e16ddfd9428b7bf9f9c200">pState</a>; <span class="comment">/* State pointer */</span>
102 <a name="l00076"></a>00076 <a class="code" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263" title="8-bit fractional data type in 1.7 format.">q7_t</a> *pCoeffs = S-><a class="code" href="structarm__fir__instance__q7.html#a0e45aedefc3fffad6cb315c5b6e5bd49">pCoeffs</a>; <span class="comment">/* Coefficient pointer */</span>
103 <a name="l00077"></a>00077 <a class="code" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263" title="8-bit fractional data type in 1.7 format.">q7_t</a> *pStateCurnt; <span class="comment">/* Points to the current sample of the state */</span>
104 <a name="l00078"></a>00078 <a class="code" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263" title="8-bit fractional data type in 1.7 format.">q7_t</a> x0, x1, x2, x3; <span class="comment">/* Temporary variables to hold state */</span>
105 <a name="l00079"></a>00079 <a class="code" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263" title="8-bit fractional data type in 1.7 format.">q7_t</a> c0; <span class="comment">/* Temporary variable to hold coefficient value */</span>
106 <a name="l00080"></a>00080 <a class="code" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263" title="8-bit fractional data type in 1.7 format.">q7_t</a> *px; <span class="comment">/* Temporary pointer for state */</span>
107 <a name="l00081"></a>00081 <a class="code" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263" title="8-bit fractional data type in 1.7 format.">q7_t</a> *pb; <span class="comment">/* Temporary pointer for coefficient buffer */</span>
108 <a name="l00082"></a>00082 <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>
109 <a name="l00083"></a>00083 uint32_t numTaps = S-><a class="code" href="structarm__fir__instance__q7.html#a9b50840e2c5ef5b17e1a584fb4cf0d06">numTaps</a>; <span class="comment">/* Number of filter coefficients in the filter */</span>
110 <a name="l00084"></a>00084 uint32_t i, tapCnt, blkCnt; <span class="comment">/* Loop counters */</span>
111 <a name="l00085"></a>00085
112 <a name="l00086"></a>00086 <span class="comment">/* S->pState points to state array which contains previous frame (numTaps - 1) samples */</span>
113 <a name="l00087"></a>00087 <span class="comment">/* pStateCurnt points to the location where the new input data should be written */</span>
114 <a name="l00088"></a>00088 pStateCurnt = &(S-><a class="code" href="structarm__fir__instance__q7.html#aaddea3b9c7e16ddfd9428b7bf9f9c200">pState</a>[(numTaps - 1u)]);
115 <a name="l00089"></a>00089
116 <a name="l00090"></a>00090 <span class="comment">/* Apply loop unrolling and compute 4 output values simultaneously. </span>
117 <a name="l00091"></a>00091 <span class="comment"> * The variables acc0 ... acc3 hold output values that are being computed: </span>
118 <a name="l00092"></a>00092 <span class="comment"> * </span>
119 <a name="l00093"></a>00093 <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>
120 <a name="l00094"></a>00094 <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>
121 <a name="l00095"></a>00095 <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>
122 <a name="l00096"></a>00096 <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>
123 <a name="l00097"></a>00097 <span class="comment"> */</span>
124 <a name="l00098"></a>00098 blkCnt = blockSize >> 2;
125 <a name="l00099"></a>00099
126 <a name="l00100"></a>00100 <span class="comment">/* First part of the processing with loop unrolling. Compute 4 outputs at a time. </span>
127 <a name="l00101"></a>00101 <span class="comment"> ** a second loop below computes the remaining 1 to 3 samples. */</span>
128 <a name="l00102"></a>00102 <span class="keywordflow">while</span>(blkCnt > 0u)
129 <a name="l00103"></a>00103 {
130 <a name="l00104"></a>00104 <span class="comment">/* Copy four new input samples into the state buffer */</span>
131 <a name="l00105"></a>00105 *pStateCurnt++ = *pSrc++;
132 <a name="l00106"></a>00106 *pStateCurnt++ = *pSrc++;
133 <a name="l00107"></a>00107 *pStateCurnt++ = *pSrc++;
134 <a name="l00108"></a>00108 *pStateCurnt++ = *pSrc++;
135 <a name="l00109"></a>00109
136 <a name="l00110"></a>00110 <span class="comment">/* Set all accumulators to zero */</span>
137 <a name="l00111"></a>00111 acc0 = 0;
138 <a name="l00112"></a>00112 acc1 = 0;
139 <a name="l00113"></a>00113 acc2 = 0;
140 <a name="l00114"></a>00114 acc3 = 0;
141 <a name="l00115"></a>00115
142 <a name="l00116"></a>00116 <span class="comment">/* Initialize state pointer */</span>
143 <a name="l00117"></a>00117 px = pState;
144 <a name="l00118"></a>00118
145 <a name="l00119"></a>00119 <span class="comment">/* Initialize coefficient pointer */</span>
146 <a name="l00120"></a>00120 pb = pCoeffs;
147 <a name="l00121"></a>00121
148 <a name="l00122"></a>00122 <span class="comment">/* Read the first three samples from the state buffer: </span>
149 <a name="l00123"></a>00123 <span class="comment"> * x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2] */</span>
150 <a name="l00124"></a>00124 x0 = *(px++);
151 <a name="l00125"></a>00125 x1 = *(px++);
152 <a name="l00126"></a>00126 x2 = *(px++);
153 <a name="l00127"></a>00127
154 <a name="l00128"></a>00128 <span class="comment">/* Loop unrolling. Process 4 taps at a time. */</span>
155 <a name="l00129"></a>00129 tapCnt = numTaps >> 2;
156 <a name="l00130"></a>00130 i = tapCnt;
157 <a name="l00131"></a>00131
158 <a name="l00132"></a>00132 <span class="keywordflow">while</span>(i > 0u)
159 <a name="l00133"></a>00133 {
160 <a name="l00134"></a>00134 <span class="comment">/* Read the b[numTaps] coefficient */</span>
161 <a name="l00135"></a>00135 c0 = *(pb++);
162 <a name="l00136"></a>00136
163 <a name="l00137"></a>00137 <span class="comment">/* Read x[n-numTaps-3] sample */</span>
164 <a name="l00138"></a>00138 x3 = *(px++);
165 <a name="l00139"></a>00139
166 <a name="l00140"></a>00140 <span class="comment">/* acc0 += b[numTaps] * x[n-numTaps] */</span>
167 <a name="l00141"></a>00141 acc0 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x0 * c0);
168 <a name="l00142"></a>00142
169 <a name="l00143"></a>00143 <span class="comment">/* acc1 += b[numTaps] * x[n-numTaps-1] */</span>
170 <a name="l00144"></a>00144 acc1 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x1 * c0);
171 <a name="l00145"></a>00145
172 <a name="l00146"></a>00146 <span class="comment">/* acc2 += b[numTaps] * x[n-numTaps-2] */</span>
173 <a name="l00147"></a>00147 acc2 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x2 * c0);
174 <a name="l00148"></a>00148
175 <a name="l00149"></a>00149 <span class="comment">/* acc3 += b[numTaps] * x[n-numTaps-3] */</span>
176 <a name="l00150"></a>00150 acc3 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x3 * c0);
177 <a name="l00151"></a>00151
178 <a name="l00152"></a>00152 <span class="comment">/* Read the b[numTaps-1] coefficient */</span>
179 <a name="l00153"></a>00153 c0 = *(pb++);
180 <a name="l00154"></a>00154
181 <a name="l00155"></a>00155 <span class="comment">/* Read x[n-numTaps-4] sample */</span>
182 <a name="l00156"></a>00156 x0 = *(px++);
183 <a name="l00157"></a>00157
184 <a name="l00158"></a>00158 <span class="comment">/* Perform the multiply-accumulates */</span>
185 <a name="l00159"></a>00159 acc0 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x1 * c0);
186 <a name="l00160"></a>00160 acc1 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x2 * c0);
187 <a name="l00161"></a>00161 acc2 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x3 * c0);
188 <a name="l00162"></a>00162 acc3 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x0 * c0);
189 <a name="l00163"></a>00163
190 <a name="l00164"></a>00164 <span class="comment">/* Read the b[numTaps-2] coefficient */</span>
191 <a name="l00165"></a>00165 c0 = *(pb++);
192 <a name="l00166"></a>00166
193 <a name="l00167"></a>00167 <span class="comment">/* Read x[n-numTaps-5] sample */</span>
194 <a name="l00168"></a>00168 x1 = *(px++);
195 <a name="l00169"></a>00169
196 <a name="l00170"></a>00170 <span class="comment">/* Perform the multiply-accumulates */</span>
197 <a name="l00171"></a>00171 acc0 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x2 * c0);
198 <a name="l00172"></a>00172 acc1 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x3 * c0);
199 <a name="l00173"></a>00173 acc2 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x0 * c0);
200 <a name="l00174"></a>00174 acc3 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x1 * c0);
201 <a name="l00175"></a>00175 <span class="comment">/* Read the b[numTaps-3] coefficients */</span>
202 <a name="l00176"></a>00176 c0 = *(pb++);
203 <a name="l00177"></a>00177
204 <a name="l00178"></a>00178 <span class="comment">/* Read x[n-numTaps-6] sample */</span>
205 <a name="l00179"></a>00179 x2 = *(px++);
206 <a name="l00180"></a>00180
207 <a name="l00181"></a>00181 <span class="comment">/* Perform the multiply-accumulates */</span>
208 <a name="l00182"></a>00182 acc0 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x3 * c0);
209 <a name="l00183"></a>00183 acc1 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x0 * c0);
210 <a name="l00184"></a>00184 acc2 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x1 * c0);
211 <a name="l00185"></a>00185 acc3 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x2 * c0);
212 <a name="l00186"></a>00186 i--;
213 <a name="l00187"></a>00187 }
214 <a name="l00188"></a>00188
215 <a name="l00189"></a>00189 <span class="comment">/* If the filter length is not a multiple of 4, compute the remaining filter taps */</span>
216 <a name="l00190"></a>00190
217 <a name="l00191"></a>00191 i = numTaps - (tapCnt * 4u);
218 <a name="l00192"></a>00192 <span class="keywordflow">while</span>(i > 0u)
219 <a name="l00193"></a>00193 {
220 <a name="l00194"></a>00194 <span class="comment">/* Read coefficients */</span>
221 <a name="l00195"></a>00195 c0 = *(pb++);
222 <a name="l00196"></a>00196
223 <a name="l00197"></a>00197 <span class="comment">/* Fetch 1 state variable */</span>
224 <a name="l00198"></a>00198 x3 = *(px++);
225 <a name="l00199"></a>00199
226 <a name="l00200"></a>00200 <span class="comment">/* Perform the multiply-accumulates */</span>
227 <a name="l00201"></a>00201 acc0 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x0 * c0);
228 <a name="l00202"></a>00202 acc1 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x1 * c0);
229 <a name="l00203"></a>00203 acc2 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x2 * c0);
230 <a name="l00204"></a>00204 acc3 += ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) x3 * c0);
231 <a name="l00205"></a>00205
232 <a name="l00206"></a>00206 <span class="comment">/* Reuse the present sample states for next sample */</span>
233 <a name="l00207"></a>00207 x0 = x1;
234 <a name="l00208"></a>00208 x1 = x2;
235 <a name="l00209"></a>00209 x2 = x3;
236 <a name="l00210"></a>00210
237 <a name="l00211"></a>00211 <span class="comment">/* Decrement the loop counter */</span>
238 <a name="l00212"></a>00212 i--;
239 <a name="l00213"></a>00213 }
240 <a name="l00214"></a>00214
241 <a name="l00215"></a>00215 <span class="comment">/* Advance the state pointer by 4 to process the next group of 4 samples */</span>
242 <a name="l00216"></a>00216 pState = pState + 4;
243 <a name="l00217"></a>00217
244 <a name="l00218"></a>00218 <span class="comment">/* The results in the 4 accumulators are in 2.62 format. Convert to 1.31 </span>
245 <a name="l00219"></a>00219 <span class="comment"> ** Then store the 4 outputs in the destination buffer. */</span>
246 <a name="l00220"></a>00220 acc0 = __SSAT((acc0 >> 7u), 8);
247 <a name="l00221"></a>00221 *pDst++ = acc0;
248 <a name="l00222"></a>00222 acc1 = __SSAT((acc1 >> 7u), 8);
249 <a name="l00223"></a>00223 *pDst++ = acc1;
250 <a name="l00224"></a>00224 acc2 = __SSAT((acc2 >> 7u), 8);
251 <a name="l00225"></a>00225 *pDst++ = acc2;
252 <a name="l00226"></a>00226 acc3 = __SSAT((acc3 >> 7u), 8);
253 <a name="l00227"></a>00227 *pDst++ = acc3;
254 <a name="l00228"></a>00228
255 <a name="l00229"></a>00229 <span class="comment">/* Decrement the samples loop counter */</span>
256 <a name="l00230"></a>00230 blkCnt--;
257 <a name="l00231"></a>00231 }
258 <a name="l00232"></a>00232
259 <a name="l00233"></a>00233
260 <a name="l00234"></a>00234 <span class="comment">/* If the blockSize is not a multiple of 4, compute any remaining output samples here. </span>
261 <a name="l00235"></a>00235 <span class="comment"> ** No loop unrolling is used. */</span>
262 <a name="l00236"></a>00236 blkCnt = blockSize % 4u;
263 <a name="l00237"></a>00237
264 <a name="l00238"></a>00238 <span class="keywordflow">while</span>(blkCnt > 0u)
265 <a name="l00239"></a>00239 {
266 <a name="l00240"></a>00240 <span class="comment">/* Copy one sample at a time into state buffer */</span>
267 <a name="l00241"></a>00241 *pStateCurnt++ = *pSrc++;
268 <a name="l00242"></a>00242
269 <a name="l00243"></a>00243 <span class="comment">/* Set the accumulator to zero */</span>
270 <a name="l00244"></a>00244 acc0 = 0;
271 <a name="l00245"></a>00245
272 <a name="l00246"></a>00246 <span class="comment">/* Initialize state pointer */</span>
273 <a name="l00247"></a>00247 px = pState;
274 <a name="l00248"></a>00248
275 <a name="l00249"></a>00249 <span class="comment">/* Initialize Coefficient pointer */</span>
276 <a name="l00250"></a>00250 pb = (pCoeffs);
277 <a name="l00251"></a>00251
278 <a name="l00252"></a>00252 i = numTaps;
279 <a name="l00253"></a>00253
280 <a name="l00254"></a>00254 <span class="comment">/* Perform the multiply-accumulates */</span>
281 <a name="l00255"></a>00255 <span class="keywordflow">do</span>
282 <a name="l00256"></a>00256 {
283 <a name="l00257"></a>00257 acc0 += (<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) * (px++) * (*(pb++));
284 <a name="l00258"></a>00258 i--;
285 <a name="l00259"></a>00259 } <span class="keywordflow">while</span>(i > 0u);
286 <a name="l00260"></a>00260
287 <a name="l00261"></a>00261 <span class="comment">/* The result is in 2.14 format. Convert to 1.7 </span>
288 <a name="l00262"></a>00262 <span class="comment"> ** Then store the output in the destination buffer. */</span>
289 <a name="l00263"></a>00263 *pDst++ = __SSAT((acc0 >> 7u), 8);
290 <a name="l00264"></a>00264
291 <a name="l00265"></a>00265 <span class="comment">/* Advance state pointer by 1 for the next sample */</span>
292 <a name="l00266"></a>00266 pState = pState + 1;
293 <a name="l00267"></a>00267
294 <a name="l00268"></a>00268 <span class="comment">/* Decrement the samples loop counter */</span>
295 <a name="l00269"></a>00269 blkCnt--;
296 <a name="l00270"></a>00270 }
297 <a name="l00271"></a>00271
298 <a name="l00272"></a>00272 <span class="comment">/* Processing is complete. </span>
299 <a name="l00273"></a>00273 <span class="comment"> ** Now copy the last numTaps - 1 samples to the satrt of the state buffer. </span>
300 <a name="l00274"></a>00274 <span class="comment"> ** This prepares the state buffer for the next function call. */</span>
301 <a name="l00275"></a>00275
302 <a name="l00276"></a>00276 <span class="comment">/* Points to the start of the state buffer */</span>
303 <a name="l00277"></a>00277 pStateCurnt = S-><a class="code" href="structarm__fir__instance__q7.html#aaddea3b9c7e16ddfd9428b7bf9f9c200">pState</a>;
304 <a name="l00278"></a>00278
305 <a name="l00279"></a>00279 tapCnt = (numTaps - 1u) >> 2u;
306 <a name="l00280"></a>00280
307 <a name="l00281"></a>00281 <span class="comment">/* copy data */</span>
308 <a name="l00282"></a>00282 <span class="keywordflow">while</span>(tapCnt > 0u)
309 <a name="l00283"></a>00283 {
310 <a name="l00284"></a>00284 *pStateCurnt++ = *pState++;
311 <a name="l00285"></a>00285 *pStateCurnt++ = *pState++;
312 <a name="l00286"></a>00286 *pStateCurnt++ = *pState++;
313 <a name="l00287"></a>00287 *pStateCurnt++ = *pState++;
314 <a name="l00288"></a>00288
315 <a name="l00289"></a>00289 <span class="comment">/* Decrement the loop counter */</span>
316 <a name="l00290"></a>00290 tapCnt--;
317 <a name="l00291"></a>00291 }
318 <a name="l00292"></a>00292
319 <a name="l00293"></a>00293 <span class="comment">/* Calculate remaining number of copies */</span>
320 <a name="l00294"></a>00294 tapCnt = (numTaps - 1u) % 0x4u;
321 <a name="l00295"></a>00295
322 <a name="l00296"></a>00296 <span class="comment">/* Copy the remaining q31_t data */</span>
323 <a name="l00297"></a>00297 <span class="keywordflow">while</span>(tapCnt > 0u)
324 <a name="l00298"></a>00298 {
325 <a name="l00299"></a>00299 *pStateCurnt++ = *pState++;
326 <a name="l00300"></a>00300
327 <a name="l00301"></a>00301 <span class="comment">/* Decrement the loop counter */</span>
328 <a name="l00302"></a>00302 tapCnt--;
329 <a name="l00303"></a>00303 }
330 <a name="l00304"></a>00304
331 <a name="l00305"></a>00305 <span class="preprocessor">#else</span>
332 <a name="l00306"></a>00306 <span class="preprocessor"></span>
333 <a name="l00307"></a>00307 <span class="comment">/* Run the below code for Cortex-M0 */</span>
334 <a name="l00308"></a>00308
335 <a name="l00309"></a>00309 uint32_t numTaps = S-><a class="code" href="structarm__fir__instance__q7.html#a9b50840e2c5ef5b17e1a584fb4cf0d06">numTaps</a>; <span class="comment">/* Number of taps in the filter */</span>
336 <a name="l00310"></a>00310 uint32_t i, blkCnt; <span class="comment">/* Loop counters */</span>
337 <a name="l00311"></a>00311 <a class="code" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263" title="8-bit fractional data type in 1.7 format.">q7_t</a> *pState = S-><a class="code" href="structarm__fir__instance__q7.html#aaddea3b9c7e16ddfd9428b7bf9f9c200">pState</a>; <span class="comment">/* State pointer */</span>
338 <a name="l00312"></a>00312 <a class="code" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263" title="8-bit fractional data type in 1.7 format.">q7_t</a> *pCoeffs = S-><a class="code" href="structarm__fir__instance__q7.html#a0e45aedefc3fffad6cb315c5b6e5bd49">pCoeffs</a>; <span class="comment">/* Coefficient pointer */</span>
339 <a name="l00313"></a>00313 <a class="code" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263" title="8-bit fractional data type in 1.7 format.">q7_t</a> *px, *pb; <span class="comment">/* Temporary pointers to state and coeff */</span>
340 <a name="l00314"></a>00314 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> acc = 0; <span class="comment">/* Accumlator */</span>
341 <a name="l00315"></a>00315 <a class="code" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263" title="8-bit fractional data type in 1.7 format.">q7_t</a> *pStateCurnt; <span class="comment">/* Points to the current sample of the state */</span>
342 <a name="l00316"></a>00316
343 <a name="l00317"></a>00317
344 <a name="l00318"></a>00318 <span class="comment">/* S->pState points to state array which contains previous frame (numTaps - 1) samples */</span>
345 <a name="l00319"></a>00319 <span class="comment">/* pStateCurnt points to the location where the new input data should be written */</span>
346 <a name="l00320"></a>00320 pStateCurnt = S-><a class="code" href="structarm__fir__instance__q7.html#aaddea3b9c7e16ddfd9428b7bf9f9c200">pState</a> + (numTaps - 1u);
347 <a name="l00321"></a>00321
348 <a name="l00322"></a>00322 <span class="comment">/* Initialize blkCnt with blockSize */</span>
349 <a name="l00323"></a>00323 blkCnt = <a class="code" href="arm__fir__example__f32_8c.html#ab6558f40a619c2502fbc24c880fd4fb0">blockSize</a>;
350 <a name="l00324"></a>00324
351 <a name="l00325"></a>00325 <span class="comment">/* Perform filtering upto BlockSize - BlockSize%4 */</span>
352 <a name="l00326"></a>00326 <span class="keywordflow">while</span>(blkCnt > 0u)
353 <a name="l00327"></a>00327 {
354 <a name="l00328"></a>00328 <span class="comment">/* Copy one sample at a time into state buffer */</span>
355 <a name="l00329"></a>00329 *pStateCurnt++ = *pSrc++;
356 <a name="l00330"></a>00330
357 <a name="l00331"></a>00331 <span class="comment">/* Set accumulator to zero */</span>
358 <a name="l00332"></a>00332 acc = 0;
359 <a name="l00333"></a>00333
360 <a name="l00334"></a>00334 <span class="comment">/* Initialize state pointer of type q7 */</span>
361 <a name="l00335"></a>00335 px = pState;
362 <a name="l00336"></a>00336
363 <a name="l00337"></a>00337 <span class="comment">/* Initialize coeff pointer of type q7 */</span>
364 <a name="l00338"></a>00338 pb = pCoeffs;
365 <a name="l00339"></a>00339
366 <a name="l00340"></a>00340
367 <a name="l00341"></a>00341 i = numTaps;
368 <a name="l00342"></a>00342
369 <a name="l00343"></a>00343 <span class="keywordflow">while</span>(i > 0u)
370 <a name="l00344"></a>00344 {
371 <a name="l00345"></a>00345 <span class="comment">/* acc = 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>
372 <a name="l00346"></a>00346 acc += (<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) * px++ * *pb++;
373 <a name="l00347"></a>00347 i--;
374 <a name="l00348"></a>00348 }
375 <a name="l00349"></a>00349
376 <a name="l00350"></a>00350 <span class="comment">/* Store the 1.7 format filter output in destination buffer */</span>
377 <a name="l00351"></a>00351 *pDst++ = (<a class="code" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263" title="8-bit fractional data type in 1.7 format.">q7_t</a>) __SSAT((acc >> 7), 8);
378 <a name="l00352"></a>00352
379 <a name="l00353"></a>00353 <span class="comment">/* Advance the state pointer by 1 to process the next sample */</span>
380 <a name="l00354"></a>00354 pState = pState + 1;
381 <a name="l00355"></a>00355
382 <a name="l00356"></a>00356 <span class="comment">/* Decrement the loop counter */</span>
383 <a name="l00357"></a>00357 blkCnt--;
384 <a name="l00358"></a>00358 }
385 <a name="l00359"></a>00359
386 <a name="l00360"></a>00360 <span class="comment">/* Processing is complete. </span>
387 <a name="l00361"></a>00361 <span class="comment"> ** Now copy the last numTaps - 1 samples to the satrt of the state buffer. </span>
388 <a name="l00362"></a>00362 <span class="comment"> ** This prepares the state buffer for the next function call. */</span>
389 <a name="l00363"></a>00363
390 <a name="l00364"></a>00364
391 <a name="l00365"></a>00365 <span class="comment">/* Points to the start of the state buffer */</span>
392 <a name="l00366"></a>00366 pStateCurnt = S-><a class="code" href="structarm__fir__instance__q7.html#aaddea3b9c7e16ddfd9428b7bf9f9c200">pState</a>;
393 <a name="l00367"></a>00367
394 <a name="l00368"></a>00368
395 <a name="l00369"></a>00369 <span class="comment">/* Copy numTaps number of values */</span>
396 <a name="l00370"></a>00370 i = (numTaps - 1u);
397 <a name="l00371"></a>00371
398 <a name="l00372"></a>00372 <span class="comment">/* Copy q7_t data */</span>
399 <a name="l00373"></a>00373 <span class="keywordflow">while</span>(i > 0u)
400 <a name="l00374"></a>00374 {
401 <a name="l00375"></a>00375 *pStateCurnt++ = *pState++;
402 <a name="l00376"></a>00376 i--;
403 <a name="l00377"></a>00377 }
404 <a name="l00378"></a>00378
405 <a name="l00379"></a>00379 <span class="preprocessor">#endif </span><span class="comment">/* #ifndef ARM_MATH_CM0 */</span>
406 <a name="l00380"></a>00380
407 <a name="l00381"></a>00381 }
408 <a name="l00382"></a>00382
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