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49 <div class="headertitle">
50 <h1>arm_fir_fast_q31.c</h1> </div>
52 <div class="contents">
53 <a href="arm__fir__fast__q31_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_q31.c </span>
61 <a name="l00009"></a>00009 <span class="comment">* </span>
62 <a name="l00010"></a>00010 <span class="comment">* Description: Processing function for the Q31 Fast FIR filter. </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 2010/08/27 </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
85 <a name="l00033"></a>00033 <span class="preprocessor">#include "<a class="code" href="arm__math_8h.html">arm_math.h</a>"</span>
86 <a name="l00034"></a>00034
87 <a name="l00066"></a><a class="code" href="group___f_i_r.html#ga55aa292e057b43c376428ea1d9a938cc">00066</a> <span class="keywordtype">void</span> <a class="code" href="group___f_i_r.html#ga55aa292e057b43c376428ea1d9a938cc" title="Processing function for the fast Q31 FIR filter for Cortex-M3 and Cortex-M4.">arm_fir_fast_q31</a>(
88 <a name="l00067"></a>00067 <span class="keyword">const</span> <a class="code" href="structarm__fir__instance__q31.html" title="Instance structure for the Q31 FIR filter.">arm_fir_instance_q31</a> * S,
89 <a name="l00068"></a>00068 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> * pSrc,
90 <a name="l00069"></a>00069 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> * pDst,
91 <a name="l00070"></a>00070 uint32_t <a class="code" href="arm__fir__example__f32_8c.html#ab6558f40a619c2502fbc24c880fd4fb0">blockSize</a>)
92 <a name="l00071"></a>00071 {
93 <a name="l00072"></a>00072 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *pState = S-><a class="code" href="structarm__fir__instance__q31.html#a409f39c93b744784648bdc365541444d">pState</a>; <span class="comment">/* State pointer */</span>
94 <a name="l00073"></a>00073 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *pCoeffs = S-><a class="code" href="structarm__fir__instance__q31.html#afaae4c884bdf11a4ec2f3b9bb2bb51d0">pCoeffs</a>; <span class="comment">/* Coefficient pointer */</span>
95 <a name="l00074"></a>00074 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> *pStateCurnt; <span class="comment">/* Points to the current sample of the state */</span>
96 <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> x0, x1, x2, x3; <span class="comment">/* Temporary variables to hold state */</span>
97 <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> c0; <span class="comment">/* Temporary variable to hold coefficient value */</span>
98 <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> *px; <span class="comment">/* Temporary pointer for state */</span>
99 <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> *pb; <span class="comment">/* Temporary pointer for coefficient buffer */</span>
100 <a name="l00079"></a>00079 <a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a> acc0, acc1, acc2, acc3; <span class="comment">/* Accumulators */</span>
101 <a name="l00080"></a>00080 uint32_t numTaps = S-><a class="code" href="structarm__fir__instance__q31.html#a918fadd775b7a0482b21bf34dae2f094">numTaps</a>; <span class="comment">/* Number of filter coefficients in the filter */</span>
102 <a name="l00081"></a>00081 uint32_t i, tapCnt, blkCnt; <span class="comment">/* Loop counters */</span>
103 <a name="l00082"></a>00082
104 <a name="l00083"></a>00083 <span class="comment">/* S->pState points to buffer which contains previous frame (numTaps - 1) samples */</span>
105 <a name="l00084"></a>00084 <span class="comment">/* pStateCurnt points to the location where the new input data should be written */</span>
106 <a name="l00085"></a>00085 pStateCurnt = &(S-><a class="code" href="structarm__fir__instance__q31.html#a409f39c93b744784648bdc365541444d">pState</a>[(numTaps - 1u)]);
107 <a name="l00086"></a>00086
108 <a name="l00087"></a>00087 <span class="comment">/* Apply loop unrolling and compute 4 output values simultaneously. </span>
109 <a name="l00088"></a>00088 <span class="comment"> * The variables acc0 ... acc3 hold output values that are being computed: </span>
110 <a name="l00089"></a>00089 <span class="comment"> * </span>
111 <a name="l00090"></a>00090 <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>
112 <a name="l00091"></a>00091 <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>
113 <a name="l00092"></a>00092 <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>
114 <a name="l00093"></a>00093 <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>
115 <a name="l00094"></a>00094 <span class="comment"> */</span>
116 <a name="l00095"></a>00095 blkCnt = blockSize >> 2;
117 <a name="l00096"></a>00096
118 <a name="l00097"></a>00097 <span class="comment">/* First part of the processing with loop unrolling. Compute 4 outputs at a time. </span>
119 <a name="l00098"></a>00098 <span class="comment"> ** a second loop below computes the remaining 1 to 3 samples. */</span>
120 <a name="l00099"></a>00099 <span class="keywordflow">while</span>(blkCnt > 0u)
121 <a name="l00100"></a>00100 {
122 <a name="l00101"></a>00101 <span class="comment">/* Copy four new input samples into the state buffer */</span>
123 <a name="l00102"></a>00102 *pStateCurnt++ = *pSrc++;
124 <a name="l00103"></a>00103 *pStateCurnt++ = *pSrc++;
125 <a name="l00104"></a>00104 *pStateCurnt++ = *pSrc++;
126 <a name="l00105"></a>00105 *pStateCurnt++ = *pSrc++;
127 <a name="l00106"></a>00106
128 <a name="l00107"></a>00107 <span class="comment">/* Set all accumulators to zero */</span>
129 <a name="l00108"></a>00108 acc0 = 0;
130 <a name="l00109"></a>00109 acc1 = 0;
131 <a name="l00110"></a>00110 acc2 = 0;
132 <a name="l00111"></a>00111 acc3 = 0;
133 <a name="l00112"></a>00112
134 <a name="l00113"></a>00113 <span class="comment">/* Initialize state pointer */</span>
135 <a name="l00114"></a>00114 px = pState;
136 <a name="l00115"></a>00115
137 <a name="l00116"></a>00116 <span class="comment">/* Initialize coefficient pointer */</span>
138 <a name="l00117"></a>00117 pb = pCoeffs;
139 <a name="l00118"></a>00118
140 <a name="l00119"></a>00119 <span class="comment">/* Read the first three samples from the state buffer: </span>
141 <a name="l00120"></a>00120 <span class="comment"> * x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2] */</span>
142 <a name="l00121"></a>00121 x0 = *(px++);
143 <a name="l00122"></a>00122 x1 = *(px++);
144 <a name="l00123"></a>00123 x2 = *(px++);
145 <a name="l00124"></a>00124
146 <a name="l00125"></a>00125 <span class="comment">/* Loop unrolling. Process 4 taps at a time. */</span>
147 <a name="l00126"></a>00126 tapCnt = numTaps >> 2;
148 <a name="l00127"></a>00127 i = tapCnt;
149 <a name="l00128"></a>00128
150 <a name="l00129"></a>00129 <span class="keywordflow">while</span>(i > 0u)
151 <a name="l00130"></a>00130 {
152 <a name="l00131"></a>00131 <span class="comment">/* Read the b[numTaps] coefficient */</span>
153 <a name="l00132"></a>00132 c0 = *(pb++);
154 <a name="l00133"></a>00133
155 <a name="l00134"></a>00134 <span class="comment">/* Read x[n-numTaps-3] sample */</span>
156 <a name="l00135"></a>00135 x3 = *(px++);
157 <a name="l00136"></a>00136
158 <a name="l00137"></a>00137 <span class="comment">/* acc0 += b[numTaps] * x[n-numTaps] */</span>
159 <a name="l00138"></a>00138 acc0 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x0 * c0) + (acc0 << 32)) >> 32);
160 <a name="l00139"></a>00139
161 <a name="l00140"></a>00140 <span class="comment">/* acc1 += b[numTaps] * x[n-numTaps-1] */</span>
162 <a name="l00141"></a>00141 acc1 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x1 * c0) + (acc1 << 32)) >> 32);
163 <a name="l00142"></a>00142
164 <a name="l00143"></a>00143 <span class="comment">/* acc2 += b[numTaps] * x[n-numTaps-2] */</span>
165 <a name="l00144"></a>00144 acc2 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x2 * c0) + (acc2 << 32)) >> 32);
166 <a name="l00145"></a>00145
167 <a name="l00146"></a>00146 <span class="comment">/* acc3 += b[numTaps] * x[n-numTaps-3] */</span>
168 <a name="l00147"></a>00147 acc3 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x3 * c0) + (acc3 << 32)) >> 32);
169 <a name="l00148"></a>00148
170 <a name="l00149"></a>00149 <span class="comment">/* Read the b[numTaps-1] coefficient */</span>
171 <a name="l00150"></a>00150 c0 = *(pb++);
172 <a name="l00151"></a>00151
173 <a name="l00152"></a>00152 <span class="comment">/* Read x[n-numTaps-4] sample */</span>
174 <a name="l00153"></a>00153 x0 = *(px++);
175 <a name="l00154"></a>00154
176 <a name="l00155"></a>00155 <span class="comment">/* Perform the multiply-accumulates */</span>
177 <a name="l00156"></a>00156 acc0 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x1 * c0) + (acc0 << 32)) >> 32);
178 <a name="l00157"></a>00157 acc1 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x2 * c0) + (acc1 << 32)) >> 32);
179 <a name="l00158"></a>00158 acc2 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x3 * c0) + (acc2 << 32)) >> 32);
180 <a name="l00159"></a>00159 acc3 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x0 * c0) + (acc3 << 32)) >> 32);
181 <a name="l00160"></a>00160
182 <a name="l00161"></a>00161 <span class="comment">/* Read the b[numTaps-2] coefficient */</span>
183 <a name="l00162"></a>00162 c0 = *(pb++);
184 <a name="l00163"></a>00163
185 <a name="l00164"></a>00164 <span class="comment">/* Read x[n-numTaps-5] sample */</span>
186 <a name="l00165"></a>00165 x1 = *(px++);
187 <a name="l00166"></a>00166
188 <a name="l00167"></a>00167 <span class="comment">/* Perform the multiply-accumulates */</span>
189 <a name="l00168"></a>00168 acc0 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x2 * c0) + (acc0 << 32)) >> 32);
190 <a name="l00169"></a>00169 acc1 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x3 * c0) + (acc1 << 32)) >> 32);
191 <a name="l00170"></a>00170 acc2 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x0 * c0) + (acc2 << 32)) >> 32);
192 <a name="l00171"></a>00171 acc3 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x1 * c0) + (acc3 << 32)) >> 32);
193 <a name="l00172"></a>00172
194 <a name="l00173"></a>00173 <span class="comment">/* Read the b[numTaps-3] coefficients */</span>
195 <a name="l00174"></a>00174 c0 = *(pb++);
196 <a name="l00175"></a>00175
197 <a name="l00176"></a>00176 <span class="comment">/* Read x[n-numTaps-6] sample */</span>
198 <a name="l00177"></a>00177 x2 = *(px++);
199 <a name="l00178"></a>00178
200 <a name="l00179"></a>00179 <span class="comment">/* Perform the multiply-accumulates */</span>
201 <a name="l00180"></a>00180 acc0 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x3 * c0) + (acc0 << 32)) >> 32);
202 <a name="l00181"></a>00181 acc1 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x0 * c0) + (acc1 << 32)) >> 32);
203 <a name="l00182"></a>00182 acc2 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x1 * c0) + (acc2 << 32)) >> 32);
204 <a name="l00183"></a>00183 acc3 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x2 * c0) + (acc3 << 32)) >> 32);
205 <a name="l00184"></a>00184 i--;
206 <a name="l00185"></a>00185 }
207 <a name="l00186"></a>00186
208 <a name="l00187"></a>00187 <span class="comment">/* If the filter length is not a multiple of 4, compute the remaining filter taps */</span>
209 <a name="l00188"></a>00188
210 <a name="l00189"></a>00189 i = numTaps - (tapCnt * 4u);
211 <a name="l00190"></a>00190 <span class="keywordflow">while</span>(i > 0u)
212 <a name="l00191"></a>00191 {
213 <a name="l00192"></a>00192 <span class="comment">/* Read coefficients */</span>
214 <a name="l00193"></a>00193 c0 = *(pb++);
215 <a name="l00194"></a>00194
216 <a name="l00195"></a>00195 <span class="comment">/* Fetch 1 state variable */</span>
217 <a name="l00196"></a>00196 x3 = *(px++);
218 <a name="l00197"></a>00197
219 <a name="l00198"></a>00198 <span class="comment">/* Perform the multiply-accumulates */</span>
220 <a name="l00199"></a>00199 acc0 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x0 * c0) + (acc0 << 32)) >> 32);
221 <a name="l00200"></a>00200 acc1 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x1 * c0) + (acc1 << 32)) >> 32);
222 <a name="l00201"></a>00201 acc2 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x2 * c0) + (acc2 << 32)) >> 32);
223 <a name="l00202"></a>00202 acc3 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) x3 * c0) + (acc3 << 32)) >> 32);
224 <a name="l00203"></a>00203
225 <a name="l00204"></a>00204 <span class="comment">/* Reuse the present sample states for next sample */</span>
226 <a name="l00205"></a>00205 x0 = x1;
227 <a name="l00206"></a>00206 x1 = x2;
228 <a name="l00207"></a>00207 x2 = x3;
229 <a name="l00208"></a>00208
230 <a name="l00209"></a>00209 <span class="comment">/* Decrement the loop counter */</span>
231 <a name="l00210"></a>00210 i--;
232 <a name="l00211"></a>00211 }
233 <a name="l00212"></a>00212
234 <a name="l00213"></a>00213 <span class="comment">/* Advance the state pointer by 4 to process the next group of 4 samples */</span>
235 <a name="l00214"></a>00214 pState = pState + 4;
236 <a name="l00215"></a>00215
237 <a name="l00216"></a>00216 <span class="comment">/* The results in the 4 accumulators are in 2.30 format. Convert to 1.31 </span>
238 <a name="l00217"></a>00217 <span class="comment"> ** Then store the 4 outputs in the destination buffer. */</span>
239 <a name="l00218"></a>00218 *pDst++ = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) (acc0 << 1);
240 <a name="l00219"></a>00219 *pDst++ = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) (acc1 << 1);
241 <a name="l00220"></a>00220 *pDst++ = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) (acc2 << 1);
242 <a name="l00221"></a>00221 *pDst++ = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) (acc3 << 1);
243 <a name="l00222"></a>00222
244 <a name="l00223"></a>00223 <span class="comment">/* Decrement the samples loop counter */</span>
245 <a name="l00224"></a>00224 blkCnt--;
246 <a name="l00225"></a>00225 }
247 <a name="l00226"></a>00226
248 <a name="l00227"></a>00227
249 <a name="l00228"></a>00228 <span class="comment">/* If the blockSize is not a multiple of 4, compute any remaining output samples here. </span>
250 <a name="l00229"></a>00229 <span class="comment"> ** No loop unrolling is used. */</span>
251 <a name="l00230"></a>00230 blkCnt = blockSize % 4u;
252 <a name="l00231"></a>00231
253 <a name="l00232"></a>00232 <span class="keywordflow">while</span>(blkCnt > 0u)
254 <a name="l00233"></a>00233 {
255 <a name="l00234"></a>00234 <span class="comment">/* Copy one sample at a time into state buffer */</span>
256 <a name="l00235"></a>00235 *pStateCurnt++ = *pSrc++;
257 <a name="l00236"></a>00236
258 <a name="l00237"></a>00237 <span class="comment">/* Set the accumulator to zero */</span>
259 <a name="l00238"></a>00238 acc0 = 0;
260 <a name="l00239"></a>00239
261 <a name="l00240"></a>00240 <span class="comment">/* Initialize state pointer */</span>
262 <a name="l00241"></a>00241 px = pState;
263 <a name="l00242"></a>00242
264 <a name="l00243"></a>00243 <span class="comment">/* Initialize Coefficient pointer */</span>
265 <a name="l00244"></a>00244 pb = (pCoeffs);
266 <a name="l00245"></a>00245
267 <a name="l00246"></a>00246 i = numTaps;
268 <a name="l00247"></a>00247
269 <a name="l00248"></a>00248 <span class="comment">/* Perform the multiply-accumulates */</span>
270 <a name="l00249"></a>00249 <span class="keywordflow">do</span>
271 <a name="l00250"></a>00250 {
272 <a name="l00251"></a>00251 acc0 = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) ((((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) * (px++) * (*(pb++))) + (acc0 << 32)) >> 32);
273 <a name="l00252"></a>00252 i--;
274 <a name="l00253"></a>00253 } <span class="keywordflow">while</span>(i > 0u);
275 <a name="l00254"></a>00254
276 <a name="l00255"></a>00255 <span class="comment">/* The result is in 2.30 format. Convert to 1.31 </span>
277 <a name="l00256"></a>00256 <span class="comment"> ** Then store the output in the destination buffer. */</span>
278 <a name="l00257"></a>00257 *pDst++ = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) (acc0 << 1);
279 <a name="l00258"></a>00258
280 <a name="l00259"></a>00259 <span class="comment">/* Advance state pointer by 1 for the next sample */</span>
281 <a name="l00260"></a>00260 pState = pState + 1;
282 <a name="l00261"></a>00261
283 <a name="l00262"></a>00262 <span class="comment">/* Decrement the samples loop counter */</span>
284 <a name="l00263"></a>00263 blkCnt--;
285 <a name="l00264"></a>00264 }
286 <a name="l00265"></a>00265
287 <a name="l00266"></a>00266 <span class="comment">/* Processing is complete. </span>
288 <a name="l00267"></a>00267 <span class="comment"> ** Now copy the last numTaps - 1 samples to the satrt of the state buffer. </span>
289 <a name="l00268"></a>00268 <span class="comment"> ** This prepares the state buffer for the next function call. */</span>
290 <a name="l00269"></a>00269
291 <a name="l00270"></a>00270 <span class="comment">/* Points to the start of the state buffer */</span>
292 <a name="l00271"></a>00271 pStateCurnt = S-><a class="code" href="structarm__fir__instance__q31.html#a409f39c93b744784648bdc365541444d">pState</a>;
293 <a name="l00272"></a>00272
294 <a name="l00273"></a>00273 tapCnt = (numTaps - 1u) >> 2u;
295 <a name="l00274"></a>00274
296 <a name="l00275"></a>00275 <span class="comment">/* copy data */</span>
297 <a name="l00276"></a>00276 <span class="keywordflow">while</span>(tapCnt > 0u)
298 <a name="l00277"></a>00277 {
299 <a name="l00278"></a>00278 *pStateCurnt++ = *pState++;
300 <a name="l00279"></a>00279 *pStateCurnt++ = *pState++;
301 <a name="l00280"></a>00280 *pStateCurnt++ = *pState++;
302 <a name="l00281"></a>00281 *pStateCurnt++ = *pState++;
303 <a name="l00282"></a>00282
304 <a name="l00283"></a>00283 <span class="comment">/* Decrement the loop counter */</span>
305 <a name="l00284"></a>00284 tapCnt--;
306 <a name="l00285"></a>00285 }
307 <a name="l00286"></a>00286
308 <a name="l00287"></a>00287 <span class="comment">/* Calculate remaining number of copies */</span>
309 <a name="l00288"></a>00288 tapCnt = (numTaps - 1u) % 0x4u;
310 <a name="l00289"></a>00289
311 <a name="l00290"></a>00290 <span class="comment">/* Copy the remaining q31_t data */</span>
312 <a name="l00291"></a>00291 <span class="keywordflow">while</span>(tapCnt > 0u)
313 <a name="l00292"></a>00292 {
314 <a name="l00293"></a>00293 *pStateCurnt++ = *pState++;
315 <a name="l00294"></a>00294
316 <a name="l00295"></a>00295 <span class="comment">/* Decrement the loop counter */</span>
317 <a name="l00296"></a>00296 tapCnt--;
318 <a name="l00297"></a>00297 }
319 <a name="l00298"></a>00298
320 <a name="l00299"></a>00299 }
321 <a name="l00300"></a>00300
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