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| <h1>arm_cfft_radix4_q31.c</h1> </div> |
| </div> |
| <div class="contents"> |
| <a href="arm__cfft__radix4__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> |
| <a name="l00002"></a>00002 <span class="comment">* Copyright (C) 2010 ARM Limited. All rights reserved. </span> |
| <a name="l00003"></a>00003 <span class="comment">* </span> |
| <a name="l00004"></a>00004 <span class="comment">* $Date: 15. July 2011 </span> |
| <a name="l00005"></a>00005 <span class="comment">* $Revision: V1.0.10 </span> |
| <a name="l00006"></a>00006 <span class="comment">* </span> |
| <a name="l00007"></a>00007 <span class="comment">* Project: CMSIS DSP Library </span> |
| <a name="l00008"></a>00008 <span class="comment">* Title: arm_cfft_radix4_q31.c </span> |
| <a name="l00009"></a>00009 <span class="comment">* </span> |
| <a name="l00010"></a>00010 <span class="comment">* Description: This file has function definition of Radix-4 FFT & IFFT function and </span> |
| <a name="l00011"></a>00011 <span class="comment">* In-place bit reversal using bit reversal table </span> |
| <a name="l00012"></a>00012 <span class="comment">* </span> |
| <a name="l00013"></a>00013 <span class="comment">* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0</span> |
| <a name="l00014"></a>00014 <span class="comment">* </span> |
| <a name="l00015"></a>00015 <span class="comment">* Version 1.0.10 2011/7/15 </span> |
| <a name="l00016"></a>00016 <span class="comment">* Big Endian support added and Merged M0 and M3/M4 Source code. </span> |
| <a name="l00017"></a>00017 <span class="comment">* </span> |
| <a name="l00018"></a>00018 <span class="comment">* Version 1.0.3 2010/11/29 </span> |
| <a name="l00019"></a>00019 <span class="comment">* Re-organized the CMSIS folders and updated documentation. </span> |
| <a name="l00020"></a>00020 <span class="comment">* </span> |
| <a name="l00021"></a>00021 <span class="comment">* Version 1.0.2 2010/11/11 </span> |
| <a name="l00022"></a>00022 <span class="comment">* Documentation updated. </span> |
| <a name="l00023"></a>00023 <span class="comment">* </span> |
| <a name="l00024"></a>00024 <span class="comment">* Version 1.0.1 2010/10/05 </span> |
| <a name="l00025"></a>00025 <span class="comment">* Production release and review comments incorporated. </span> |
| <a name="l00026"></a>00026 <span class="comment">* </span> |
| <a name="l00027"></a>00027 <span class="comment">* Version 1.0.0 2010/09/20 </span> |
| <a name="l00028"></a>00028 <span class="comment">* Production release and review comments incorporated. </span> |
| <a name="l00029"></a>00029 <span class="comment">* </span> |
| <a name="l00030"></a>00030 <span class="comment">* Version 0.0.5 2010/04/26 </span> |
| <a name="l00031"></a>00031 <span class="comment">* incorporated review comments and updated with latest CMSIS layer </span> |
| <a name="l00032"></a>00032 <span class="comment">* </span> |
| <a name="l00033"></a>00033 <span class="comment">* Version 0.0.3 2010/03/10 </span> |
| <a name="l00034"></a>00034 <span class="comment">* Initial version </span> |
| <a name="l00035"></a>00035 <span class="comment">* -------------------------------------------------------------------- */</span> |
| <a name="l00036"></a>00036 <span class="preprocessor">#include "<a class="code" href="arm__math_8h.html">arm_math.h</a>"</span> |
| <a name="l00037"></a>00037 |
| <a name="l00038"></a>00038 |
| <a name="l00066"></a><a class="code" href="group___c_f_f_t___c_i_f_f_t.html#gafde3ee1f58cf393b45a9073174fff548">00066</a> <span class="keywordtype">void</span> <a class="code" href="group___c_f_f_t___c_i_f_f_t.html#gafde3ee1f58cf393b45a9073174fff548" title="Processing function for the Q31 CFFT/CIFFT.">arm_cfft_radix4_q31</a>( |
| <a name="l00067"></a>00067 <span class="keyword">const</span> <a class="code" href="structarm__cfft__radix4__instance__q31.html" title="Instance structure for the Q31 CFFT/CIFFT function.">arm_cfft_radix4_instance_q31</a> * S, |
| <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) |
| <a name="l00069"></a>00069 { |
| <a name="l00070"></a>00070 <span class="keywordflow">if</span>(S-><a class="code" href="structarm__cfft__radix4__instance__q31.html#adc0a62ba669ad2282ecbe43d5d96abab">ifftFlag</a> == 1u) |
| <a name="l00071"></a>00071 { |
| <a name="l00072"></a>00072 <span class="comment">/* Complex IFFT radix-4 */</span> |
| <a name="l00073"></a>00073 <a class="code" href="arm__cfft__radix4__q31_8c.html#ac9c7c553114c1201a3a987a11b8a6d01" title="Core function for the Q31 CIFFT butterfly process.">arm_radix4_butterfly_inverse_q31</a>(pSrc, S-><a class="code" href="structarm__cfft__radix4__instance__q31.html#ab413d2a5d3f45fa187d93813bf3bf81b">fftLen</a>, S-><a class="code" href="structarm__cfft__radix4__instance__q31.html#a561c22dee4cbdcfa0fd5f15106ecc306">pTwiddle</a>, |
| <a name="l00074"></a>00074 S-><a class="code" href="structarm__cfft__radix4__instance__q31.html#a8cf8187b8232815cf17ee82bf572ecf9">twidCoefModifier</a>); |
| <a name="l00075"></a>00075 } |
| <a name="l00076"></a>00076 <span class="keywordflow">else</span> |
| <a name="l00077"></a>00077 { |
| <a name="l00078"></a>00078 <span class="comment">/* Complex FFT radix-4 */</span> |
| <a name="l00079"></a>00079 <a class="code" href="arm__cfft__radix4__q31_8c.html#ac12f1e7f159d5741358cdc36830a0395" title="Core function for the Q31 CFFT butterfly process.">arm_radix4_butterfly_q31</a>(pSrc, S-><a class="code" href="structarm__cfft__radix4__instance__q31.html#ab413d2a5d3f45fa187d93813bf3bf81b">fftLen</a>, S-><a class="code" href="structarm__cfft__radix4__instance__q31.html#a561c22dee4cbdcfa0fd5f15106ecc306">pTwiddle</a>, |
| <a name="l00080"></a>00080 S-><a class="code" href="structarm__cfft__radix4__instance__q31.html#a8cf8187b8232815cf17ee82bf572ecf9">twidCoefModifier</a>); |
| <a name="l00081"></a>00081 } |
| <a name="l00082"></a>00082 |
| <a name="l00083"></a>00083 |
| <a name="l00084"></a>00084 <span class="keywordflow">if</span>(S-><a class="code" href="structarm__cfft__radix4__instance__q31.html#a5a7c4f4c7b3fb655cbb2bc11ef160a2a">bitReverseFlag</a> == 1u) |
| <a name="l00085"></a>00085 { |
| <a name="l00086"></a>00086 <span class="comment">/* Bit Reversal */</span> |
| <a name="l00087"></a>00087 <a class="code" href="arm__cfft__radix4__q31_8c.html#a27618705158b5c42db5fb0a381f8efc1" title="In-place bit reversal function.">arm_bitreversal_q31</a>(pSrc, S-><a class="code" href="structarm__cfft__radix4__instance__q31.html#ab413d2a5d3f45fa187d93813bf3bf81b">fftLen</a>, S-><a class="code" href="structarm__cfft__radix4__instance__q31.html#a94d2fead4efa4d5eaae142bbe30b0e15">bitRevFactor</a>, S-><a class="code" href="structarm__cfft__radix4__instance__q31.html#a33a3bc774c97373261699463c05dfe54">pBitRevTable</a>); |
| <a name="l00088"></a>00088 } |
| <a name="l00089"></a>00089 |
| <a name="l00090"></a>00090 } |
| <a name="l00091"></a>00091 |
| <a name="l00096"></a>00096 <span class="comment">/* </span> |
| <a name="l00097"></a>00097 <span class="comment">* Radix-4 FFT algorithm used is : </span> |
| <a name="l00098"></a>00098 <span class="comment">* </span> |
| <a name="l00099"></a>00099 <span class="comment">* Input real and imaginary data: </span> |
| <a name="l00100"></a>00100 <span class="comment">* x(n) = xa + j * ya </span> |
| <a name="l00101"></a>00101 <span class="comment">* x(n+N/4 ) = xb + j * yb </span> |
| <a name="l00102"></a>00102 <span class="comment">* x(n+N/2 ) = xc + j * yc </span> |
| <a name="l00103"></a>00103 <span class="comment">* x(n+3N 4) = xd + j * yd </span> |
| <a name="l00104"></a>00104 <span class="comment">* </span> |
| <a name="l00105"></a>00105 <span class="comment">* </span> |
| <a name="l00106"></a>00106 <span class="comment">* Output real and imaginary data: </span> |
| <a name="l00107"></a>00107 <span class="comment">* x(4r) = xa'+ j * ya' </span> |
| <a name="l00108"></a>00108 <span class="comment">* x(4r+1) = xb'+ j * yb' </span> |
| <a name="l00109"></a>00109 <span class="comment">* x(4r+2) = xc'+ j * yc' </span> |
| <a name="l00110"></a>00110 <span class="comment">* x(4r+3) = xd'+ j * yd' </span> |
| <a name="l00111"></a>00111 <span class="comment">* </span> |
| <a name="l00112"></a>00112 <span class="comment">* </span> |
| <a name="l00113"></a>00113 <span class="comment">* Twiddle factors for radix-4 FFT: </span> |
| <a name="l00114"></a>00114 <span class="comment">* Wn = co1 + j * (- si1) </span> |
| <a name="l00115"></a>00115 <span class="comment">* W2n = co2 + j * (- si2) </span> |
| <a name="l00116"></a>00116 <span class="comment">* W3n = co3 + j * (- si3) </span> |
| <a name="l00117"></a>00117 <span class="comment">* </span> |
| <a name="l00118"></a>00118 <span class="comment">* Butterfly implementation: </span> |
| <a name="l00119"></a>00119 <span class="comment">* xa' = xa + xb + xc + xd </span> |
| <a name="l00120"></a>00120 <span class="comment">* ya' = ya + yb + yc + yd </span> |
| <a name="l00121"></a>00121 <span class="comment">* xb' = (xa+yb-xc-yd)* co1 + (ya-xb-yc+xd)* (si1) </span> |
| <a name="l00122"></a>00122 <span class="comment">* yb' = (ya-xb-yc+xd)* co1 - (xa+yb-xc-yd)* (si1) </span> |
| <a name="l00123"></a>00123 <span class="comment">* xc' = (xa-xb+xc-xd)* co2 + (ya-yb+yc-yd)* (si2) </span> |
| <a name="l00124"></a>00124 <span class="comment">* yc' = (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2) </span> |
| <a name="l00125"></a>00125 <span class="comment">* xd' = (xa-yb-xc+yd)* co3 + (ya+xb-yc-xd)* (si3) </span> |
| <a name="l00126"></a>00126 <span class="comment">* yd' = (ya+xb-yc-xd)* co3 - (xa-yb-xc+yd)* (si3) </span> |
| <a name="l00127"></a>00127 <span class="comment">* </span> |
| <a name="l00128"></a>00128 <span class="comment">*/</span> |
| <a name="l00129"></a>00129 |
| <a name="l00139"></a><a class="code" href="arm__math_8h.html#ac12f1e7f159d5741358cdc36830a0395">00139</a> <span class="keywordtype">void</span> <a class="code" href="arm__cfft__radix4__q31_8c.html#ac12f1e7f159d5741358cdc36830a0395" title="Core function for the Q31 CFFT butterfly process.">arm_radix4_butterfly_q31</a>( |
| <a name="l00140"></a>00140 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> * pSrc, |
| <a name="l00141"></a>00141 uint32_t fftLen, |
| <a name="l00142"></a>00142 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> * pCoef, |
| <a name="l00143"></a>00143 uint32_t twidCoefModifier) |
| <a name="l00144"></a>00144 { |
| <a name="l00145"></a>00145 uint32_t n1, n2, ia1, ia2, ia3, i0, i1, i2, i3, j, k; |
| <a name="l00146"></a>00146 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> t1, t2, r1, r2, s1, s2, co1, co2, co3, si1, si2, si3; |
| <a name="l00147"></a>00147 |
| <a name="l00148"></a>00148 |
| <a name="l00149"></a>00149 <span class="comment">/* Total process is divided into three stages */</span> |
| <a name="l00150"></a>00150 |
| <a name="l00151"></a>00151 <span class="comment">/* process first stage, middle stages, & last stage */</span> |
| <a name="l00152"></a>00152 |
| <a name="l00153"></a>00153 |
| <a name="l00154"></a>00154 <span class="comment">/* start of first stage process */</span> |
| <a name="l00155"></a>00155 |
| <a name="l00156"></a>00156 <span class="comment">/* Initializations for the first stage */</span> |
| <a name="l00157"></a>00157 n2 = fftLen; |
| <a name="l00158"></a>00158 n1 = n2; |
| <a name="l00159"></a>00159 <span class="comment">/* n2 = fftLen/4 */</span> |
| <a name="l00160"></a>00160 n2 >>= 2u; |
| <a name="l00161"></a>00161 i0 = 0u; |
| <a name="l00162"></a>00162 ia1 = 0u; |
| <a name="l00163"></a>00163 |
| <a name="l00164"></a>00164 j = n2; |
| <a name="l00165"></a>00165 |
| <a name="l00166"></a>00166 <span class="comment">/* Calculation of first stage */</span> |
| <a name="l00167"></a>00167 <span class="keywordflow">do</span> |
| <a name="l00168"></a>00168 { |
| <a name="l00169"></a>00169 <span class="comment">/* index calculation for the input as, */</span> |
| <a name="l00170"></a>00170 <span class="comment">/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2u], pSrc[i0 + 3fftLen/4] */</span> |
| <a name="l00171"></a>00171 i1 = i0 + n2; |
| <a name="l00172"></a>00172 i2 = i1 + n2; |
| <a name="l00173"></a>00173 i3 = i2 + n2; |
| <a name="l00174"></a>00174 |
| <a name="l00175"></a>00175 <span class="comment">/* input is in 1.31(q31) format and provide 4 guard bits for the input */</span> |
| <a name="l00176"></a>00176 |
| <a name="l00177"></a>00177 <span class="comment">/* Butterfly implementation */</span> |
| <a name="l00178"></a>00178 <span class="comment">/* xa + xc */</span> |
| <a name="l00179"></a>00179 r1 = (pSrc[(2u * i0)] >> 4u) + (pSrc[(2u * i2)] >> 4u); |
| <a name="l00180"></a>00180 <span class="comment">/* xa - xc */</span> |
| <a name="l00181"></a>00181 r2 = (pSrc[2u * i0] >> 4u) - (pSrc[2u * i2] >> 4u); |
| <a name="l00182"></a>00182 |
| <a name="l00183"></a>00183 <span class="comment">/* ya + yc */</span> |
| <a name="l00184"></a>00184 s1 = (pSrc[(2u * i0) + 1u] >> 4u) + (pSrc[(2u * i2) + 1u] >> 4u); |
| <a name="l00185"></a>00185 <span class="comment">/* ya - yc */</span> |
| <a name="l00186"></a>00186 s2 = (pSrc[(2u * i0) + 1u] >> 4u) - (pSrc[(2u * i2) + 1u] >> 4u); |
| <a name="l00187"></a>00187 |
| <a name="l00188"></a>00188 <span class="comment">/* xb + xd */</span> |
| <a name="l00189"></a>00189 t1 = (pSrc[2u * i1] >> 4u) + (pSrc[2u * i3] >> 4u); |
| <a name="l00190"></a>00190 |
| <a name="l00191"></a>00191 <span class="comment">/* xa' = xa + xb + xc + xd */</span> |
| <a name="l00192"></a>00192 pSrc[2u * i0] = (r1 + t1); |
| <a name="l00193"></a>00193 <span class="comment">/* (xa + xc) - (xb + xd) */</span> |
| <a name="l00194"></a>00194 r1 = r1 - t1; |
| <a name="l00195"></a>00195 <span class="comment">/* yb + yd */</span> |
| <a name="l00196"></a>00196 t2 = (pSrc[(2u * i1) + 1u] >> 4u) + (pSrc[(2u * i3) + 1u] >> 4u); |
| <a name="l00197"></a>00197 <span class="comment">/* ya' = ya + yb + yc + yd */</span> |
| <a name="l00198"></a>00198 pSrc[(2u * i0) + 1u] = (s1 + t2); |
| <a name="l00199"></a>00199 |
| <a name="l00200"></a>00200 <span class="comment">/* (ya + yc) - (yb + yd) */</span> |
| <a name="l00201"></a>00201 s1 = s1 - t2; |
| <a name="l00202"></a>00202 |
| <a name="l00203"></a>00203 <span class="comment">/* yb - yd */</span> |
| <a name="l00204"></a>00204 t1 = (pSrc[(2u * i1) + 1u] >> 4u) - (pSrc[(2u * i3) + 1u] >> 4u); |
| <a name="l00205"></a>00205 <span class="comment">/* xb - xd */</span> |
| <a name="l00206"></a>00206 t2 = (pSrc[2u * i1] >> 4u) - (pSrc[2u * i3] >> 4u); |
| <a name="l00207"></a>00207 |
| <a name="l00208"></a>00208 <span class="comment">/* index calculation for the coefficients */</span> |
| <a name="l00209"></a>00209 ia2 = 2u * ia1; |
| <a name="l00210"></a>00210 co2 = pCoef[ia2 * 2u]; |
| <a name="l00211"></a>00211 si2 = pCoef[(ia2 * 2u) + 1u]; |
| <a name="l00212"></a>00212 |
| <a name="l00213"></a>00213 <span class="comment">/* xc' = (xa-xb+xc-xd)co2 + (ya-yb+yc-yd)(si2) */</span> |
| <a name="l00214"></a>00214 pSrc[2u * i1] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * co2) >> 32)) + |
| <a name="l00215"></a>00215 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * si2) >> 32))) << 1u; |
| <a name="l00216"></a>00216 |
| <a name="l00217"></a>00217 <span class="comment">/* yc' = (ya-yb+yc-yd)co2 - (xa-xb+xc-xd)(si2) */</span> |
| <a name="l00218"></a>00218 pSrc[(2u * i1) + 1u] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * co2) >> 32)) - |
| <a name="l00219"></a>00219 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * si2) >> 32))) << 1u; |
| <a name="l00220"></a>00220 |
| <a name="l00221"></a>00221 <span class="comment">/* (xa - xc) + (yb - yd) */</span> |
| <a name="l00222"></a>00222 r1 = r2 + t1; |
| <a name="l00223"></a>00223 <span class="comment">/* (xa - xc) - (yb - yd) */</span> |
| <a name="l00224"></a>00224 r2 = r2 - t1; |
| <a name="l00225"></a>00225 |
| <a name="l00226"></a>00226 <span class="comment">/* (ya - yc) - (xb - xd) */</span> |
| <a name="l00227"></a>00227 s1 = s2 - t2; |
| <a name="l00228"></a>00228 <span class="comment">/* (ya - yc) + (xb - xd) */</span> |
| <a name="l00229"></a>00229 s2 = s2 + t2; |
| <a name="l00230"></a>00230 |
| <a name="l00231"></a>00231 co1 = pCoef[ia1 * 2u]; |
| <a name="l00232"></a>00232 si1 = pCoef[(ia1 * 2u) + 1u]; |
| <a name="l00233"></a>00233 |
| <a name="l00234"></a>00234 <span class="comment">/* xb' = (xa+yb-xc-yd)co1 + (ya-xb-yc+xd)(si1) */</span> |
| <a name="l00235"></a>00235 pSrc[2u * i2] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * co1) >> 32)) + |
| <a name="l00236"></a>00236 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * si1) >> 32))) << 1u; |
| <a name="l00237"></a>00237 |
| <a name="l00238"></a>00238 <span class="comment">/* yb' = (ya-xb-yc+xd)co1 - (xa+yb-xc-yd)(si1) */</span> |
| <a name="l00239"></a>00239 pSrc[(2u * i2) + 1u] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * co1) >> 32)) - |
| <a name="l00240"></a>00240 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * si1) >> 32))) << 1u; |
| <a name="l00241"></a>00241 |
| <a name="l00242"></a>00242 <span class="comment">/* index calculation for the coefficients */</span> |
| <a name="l00243"></a>00243 ia3 = 3u * ia1; |
| <a name="l00244"></a>00244 co3 = pCoef[ia3 * 2u]; |
| <a name="l00245"></a>00245 si3 = pCoef[(ia3 * 2u) + 1u]; |
| <a name="l00246"></a>00246 |
| <a name="l00247"></a>00247 <span class="comment">/* xd' = (xa-yb-xc+yd)co3 + (ya+xb-yc-xd)(si3) */</span> |
| <a name="l00248"></a>00248 pSrc[2u * i3] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r2 * co3) >> 32)) + |
| <a name="l00249"></a>00249 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s2 * si3) >> 32))) << 1u; |
| <a name="l00250"></a>00250 |
| <a name="l00251"></a>00251 <span class="comment">/* yd' = (ya+xb-yc-xd)co3 - (xa-yb-xc+yd)(si3) */</span> |
| <a name="l00252"></a>00252 pSrc[(2u * i3) + 1u] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s2 * co3) >> 32)) - |
| <a name="l00253"></a>00253 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r2 * si3) >> 32))) << 1u; |
| <a name="l00254"></a>00254 |
| <a name="l00255"></a>00255 <span class="comment">/* Twiddle coefficients index modifier */</span> |
| <a name="l00256"></a>00256 ia1 = ia1 + twidCoefModifier; |
| <a name="l00257"></a>00257 |
| <a name="l00258"></a>00258 <span class="comment">/* Updating input index */</span> |
| <a name="l00259"></a>00259 i0 = i0 + 1u; |
| <a name="l00260"></a>00260 |
| <a name="l00261"></a>00261 } <span class="keywordflow">while</span>(--j); |
| <a name="l00262"></a>00262 |
| <a name="l00263"></a>00263 <span class="comment">/* end of first stage process */</span> |
| <a name="l00264"></a>00264 |
| <a name="l00265"></a>00265 <span class="comment">/* data is in 5.27(q27) format */</span> |
| <a name="l00266"></a>00266 |
| <a name="l00267"></a>00267 |
| <a name="l00268"></a>00268 <span class="comment">/* start of Middle stages process */</span> |
| <a name="l00269"></a>00269 |
| <a name="l00270"></a>00270 |
| <a name="l00271"></a>00271 <span class="comment">/* each stage in middle stages provides two down scaling of the input */</span> |
| <a name="l00272"></a>00272 |
| <a name="l00273"></a>00273 twidCoefModifier <<= 2u; |
| <a name="l00274"></a>00274 |
| <a name="l00275"></a>00275 |
| <a name="l00276"></a>00276 <span class="keywordflow">for</span> (k = fftLen / 4u; k > 4u; k >>= 2u) |
| <a name="l00277"></a>00277 { |
| <a name="l00278"></a>00278 <span class="comment">/* Initializations for the first stage */</span> |
| <a name="l00279"></a>00279 n1 = n2; |
| <a name="l00280"></a>00280 n2 >>= 2u; |
| <a name="l00281"></a>00281 ia1 = 0u; |
| <a name="l00282"></a>00282 |
| <a name="l00283"></a>00283 <span class="comment">/* Calculation of first stage */</span> |
| <a name="l00284"></a>00284 <span class="keywordflow">for</span> (j = 0u; j <= (n2 - 1u); j++) |
| <a name="l00285"></a>00285 { |
| <a name="l00286"></a>00286 <span class="comment">/* index calculation for the coefficients */</span> |
| <a name="l00287"></a>00287 ia2 = ia1 + ia1; |
| <a name="l00288"></a>00288 ia3 = ia2 + ia1; |
| <a name="l00289"></a>00289 co1 = pCoef[ia1 * 2u]; |
| <a name="l00290"></a>00290 si1 = pCoef[(ia1 * 2u) + 1u]; |
| <a name="l00291"></a>00291 co2 = pCoef[ia2 * 2u]; |
| <a name="l00292"></a>00292 si2 = pCoef[(ia2 * 2u) + 1u]; |
| <a name="l00293"></a>00293 co3 = pCoef[ia3 * 2u]; |
| <a name="l00294"></a>00294 si3 = pCoef[(ia3 * 2u) + 1u]; |
| <a name="l00295"></a>00295 <span class="comment">/* Twiddle coefficients index modifier */</span> |
| <a name="l00296"></a>00296 ia1 = ia1 + twidCoefModifier; |
| <a name="l00297"></a>00297 |
| <a name="l00298"></a>00298 <span class="keywordflow">for</span> (i0 = j; i0 < fftLen; i0 += n1) |
| <a name="l00299"></a>00299 { |
| <a name="l00300"></a>00300 <span class="comment">/* index calculation for the input as, */</span> |
| <a name="l00301"></a>00301 <span class="comment">/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2u], pSrc[i0 + 3fftLen/4] */</span> |
| <a name="l00302"></a>00302 i1 = i0 + n2; |
| <a name="l00303"></a>00303 i2 = i1 + n2; |
| <a name="l00304"></a>00304 i3 = i2 + n2; |
| <a name="l00305"></a>00305 |
| <a name="l00306"></a>00306 <span class="comment">/* Butterfly implementation */</span> |
| <a name="l00307"></a>00307 <span class="comment">/* xa + xc */</span> |
| <a name="l00308"></a>00308 r1 = pSrc[2u * i0] + pSrc[2u * i2]; |
| <a name="l00309"></a>00309 <span class="comment">/* xa - xc */</span> |
| <a name="l00310"></a>00310 r2 = pSrc[2u * i0] - pSrc[2u * i2]; |
| <a name="l00311"></a>00311 |
| <a name="l00312"></a>00312 <span class="comment">/* ya + yc */</span> |
| <a name="l00313"></a>00313 s1 = pSrc[(2u * i0) + 1u] + pSrc[(2u * i2) + 1u]; |
| <a name="l00314"></a>00314 <span class="comment">/* ya - yc */</span> |
| <a name="l00315"></a>00315 s2 = pSrc[(2u * i0) + 1u] - pSrc[(2u * i2) + 1u]; |
| <a name="l00316"></a>00316 |
| <a name="l00317"></a>00317 <span class="comment">/* xb + xd */</span> |
| <a name="l00318"></a>00318 t1 = pSrc[2u * i1] + pSrc[2u * i3]; |
| <a name="l00319"></a>00319 |
| <a name="l00320"></a>00320 <span class="comment">/* xa' = xa + xb + xc + xd */</span> |
| <a name="l00321"></a>00321 pSrc[2u * i0] = (r1 + t1) >> 2u; |
| <a name="l00322"></a>00322 <span class="comment">/* xa + xc -(xb + xd) */</span> |
| <a name="l00323"></a>00323 r1 = r1 - t1; |
| <a name="l00324"></a>00324 |
| <a name="l00325"></a>00325 <span class="comment">/* yb + yd */</span> |
| <a name="l00326"></a>00326 t2 = pSrc[(2u * i1) + 1u] + pSrc[(2u * i3) + 1u]; |
| <a name="l00327"></a>00327 <span class="comment">/* ya' = ya + yb + yc + yd */</span> |
| <a name="l00328"></a>00328 pSrc[(2u * i0) + 1u] = (s1 + t2) >> 2u; |
| <a name="l00329"></a>00329 |
| <a name="l00330"></a>00330 <span class="comment">/* (ya + yc) - (yb + yd) */</span> |
| <a name="l00331"></a>00331 s1 = s1 - t2; |
| <a name="l00332"></a>00332 |
| <a name="l00333"></a>00333 <span class="comment">/* (yb - yd) */</span> |
| <a name="l00334"></a>00334 t1 = pSrc[(2u * i1) + 1u] - pSrc[(2u * i3) + 1u]; |
| <a name="l00335"></a>00335 <span class="comment">/* (xb - xd) */</span> |
| <a name="l00336"></a>00336 t2 = pSrc[2u * i1] - pSrc[2u * i3]; |
| <a name="l00337"></a>00337 |
| <a name="l00338"></a>00338 <span class="comment">/* xc' = (xa-xb+xc-xd)co2 + (ya-yb+yc-yd)(si2) */</span> |
| <a name="l00339"></a>00339 pSrc[2u * i1] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * co2) >> 32)) + |
| <a name="l00340"></a>00340 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * si2) >> 32))) >> 1u; |
| <a name="l00341"></a>00341 |
| <a name="l00342"></a>00342 <span class="comment">/* yc' = (ya-yb+yc-yd)co2 - (xa-xb+xc-xd)(si2) */</span> |
| <a name="l00343"></a>00343 pSrc[(2u * i1) + 1u] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * co2) >> 32)) - |
| <a name="l00344"></a>00344 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * si2) >> 32))) >> 1u; |
| <a name="l00345"></a>00345 |
| <a name="l00346"></a>00346 <span class="comment">/* (xa - xc) + (yb - yd) */</span> |
| <a name="l00347"></a>00347 r1 = r2 + t1; |
| <a name="l00348"></a>00348 <span class="comment">/* (xa - xc) - (yb - yd) */</span> |
| <a name="l00349"></a>00349 r2 = r2 - t1; |
| <a name="l00350"></a>00350 |
| <a name="l00351"></a>00351 <span class="comment">/* (ya - yc) - (xb - xd) */</span> |
| <a name="l00352"></a>00352 s1 = s2 - t2; |
| <a name="l00353"></a>00353 <span class="comment">/* (ya - yc) + (xb - xd) */</span> |
| <a name="l00354"></a>00354 s2 = s2 + t2; |
| <a name="l00355"></a>00355 |
| <a name="l00356"></a>00356 <span class="comment">/* xb' = (xa+yb-xc-yd)co1 + (ya-xb-yc+xd)(si1) */</span> |
| <a name="l00357"></a>00357 pSrc[2u * i2] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * co1) >> 32)) + |
| <a name="l00358"></a>00358 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * si1) >> 32))) >> 1u; |
| <a name="l00359"></a>00359 |
| <a name="l00360"></a>00360 <span class="comment">/* yb' = (ya-xb-yc+xd)co1 - (xa+yb-xc-yd)(si1) */</span> |
| <a name="l00361"></a>00361 pSrc[(2u * i2) + 1u] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * co1) >> 32)) - |
| <a name="l00362"></a>00362 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * si1) >> 32))) >> 1u; |
| <a name="l00363"></a>00363 |
| <a name="l00364"></a>00364 <span class="comment">/* xd' = (xa-yb-xc+yd)co3 + (ya+xb-yc-xd)(si3) */</span> |
| <a name="l00365"></a>00365 pSrc[2u * i3] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r2 * co3) >> 32)) + |
| <a name="l00366"></a>00366 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s2 * si3) >> 32))) >> 1u; |
| <a name="l00367"></a>00367 |
| <a name="l00368"></a>00368 <span class="comment">/* yd' = (ya+xb-yc-xd)co3 - (xa-yb-xc+yd)(si3) */</span> |
| <a name="l00369"></a>00369 pSrc[(2u * i3) + 1u] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s2 * co3) >> 32)) - |
| <a name="l00370"></a>00370 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r2 * si3) >> 32))) >> 1u; |
| <a name="l00371"></a>00371 } |
| <a name="l00372"></a>00372 } |
| <a name="l00373"></a>00373 twidCoefModifier <<= 2u; |
| <a name="l00374"></a>00374 } |
| <a name="l00375"></a>00375 |
| <a name="l00376"></a>00376 <span class="comment">/* End of Middle stages process */</span> |
| <a name="l00377"></a>00377 |
| <a name="l00378"></a>00378 <span class="comment">/* data is in 11.21(q21) format for the 1024 point as there are 3 middle stages */</span> |
| <a name="l00379"></a>00379 <span class="comment">/* data is in 9.23(q23) format for the 256 point as there are 2 middle stages */</span> |
| <a name="l00380"></a>00380 <span class="comment">/* data is in 7.25(q25) format for the 64 point as there are 1 middle stage */</span> |
| <a name="l00381"></a>00381 <span class="comment">/* data is in 5.27(q27) format for the 16 point as there are no middle stages */</span> |
| <a name="l00382"></a>00382 |
| <a name="l00383"></a>00383 |
| <a name="l00384"></a>00384 <span class="comment">/* start of Last stage process */</span> |
| <a name="l00385"></a>00385 |
| <a name="l00386"></a>00386 <span class="comment">/* Initializations of last stage */</span> |
| <a name="l00387"></a>00387 n1 = n2; |
| <a name="l00388"></a>00388 n2 >>= 2u; |
| <a name="l00389"></a>00389 |
| <a name="l00390"></a>00390 <span class="comment">/* Calculations of last stage */</span> |
| <a name="l00391"></a>00391 <span class="keywordflow">for</span> (i0 = 0u; i0 <= (fftLen - n1); i0 += n1) |
| <a name="l00392"></a>00392 { |
| <a name="l00393"></a>00393 <span class="comment">/* index calculation for the input as, */</span> |
| <a name="l00394"></a>00394 <span class="comment">/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2u], pSrc[i0 + 3fftLen/4] */</span> |
| <a name="l00395"></a>00395 i1 = i0 + n2; |
| <a name="l00396"></a>00396 i2 = i1 + n2; |
| <a name="l00397"></a>00397 i3 = i2 + n2; |
| <a name="l00398"></a>00398 |
| <a name="l00399"></a>00399 <span class="comment">/* Butterfly implementation */</span> |
| <a name="l00400"></a>00400 <span class="comment">/* xa + xb */</span> |
| <a name="l00401"></a>00401 r1 = pSrc[2u * i0] + pSrc[2u * i2]; |
| <a name="l00402"></a>00402 <span class="comment">/* xa - xb */</span> |
| <a name="l00403"></a>00403 r2 = pSrc[2u * i0] - pSrc[2u * i2]; |
| <a name="l00404"></a>00404 |
| <a name="l00405"></a>00405 <span class="comment">/* ya + yc */</span> |
| <a name="l00406"></a>00406 s1 = pSrc[(2u * i0) + 1u] + pSrc[(2u * i2) + 1u]; |
| <a name="l00407"></a>00407 <span class="comment">/* ya - yc */</span> |
| <a name="l00408"></a>00408 s2 = pSrc[(2u * i0) + 1u] - pSrc[(2u * i2) + 1u]; |
| <a name="l00409"></a>00409 |
| <a name="l00410"></a>00410 <span class="comment">/* xc + xd */</span> |
| <a name="l00411"></a>00411 t1 = pSrc[2u * i1] + pSrc[2u * i3]; |
| <a name="l00412"></a>00412 <span class="comment">/* xa' = xa + xb + xc + xd */</span> |
| <a name="l00413"></a>00413 pSrc[2u * i0] = (r1 + t1); |
| <a name="l00414"></a>00414 <span class="comment">/* (xa + xb) - (xc + xd) */</span> |
| <a name="l00415"></a>00415 r1 = r1 - t1; |
| <a name="l00416"></a>00416 |
| <a name="l00417"></a>00417 <span class="comment">/* yb + yd */</span> |
| <a name="l00418"></a>00418 t2 = pSrc[(2u * i1) + 1u] + pSrc[(2u * i3) + 1u]; |
| <a name="l00419"></a>00419 <span class="comment">/* ya' = ya + yb + yc + yd */</span> |
| <a name="l00420"></a>00420 pSrc[(2u * i0) + 1u] = (s1 + t2); |
| <a name="l00421"></a>00421 <span class="comment">/* (ya + yc) - (yb + yd) */</span> |
| <a name="l00422"></a>00422 s1 = s1 - t2; |
| <a name="l00423"></a>00423 |
| <a name="l00424"></a>00424 <span class="comment">/* (yb-yd) */</span> |
| <a name="l00425"></a>00425 t1 = pSrc[(2u * i1) + 1u] - pSrc[(2u * i3) + 1u]; |
| <a name="l00426"></a>00426 <span class="comment">/* (xb-xd) */</span> |
| <a name="l00427"></a>00427 t2 = pSrc[2u * i1] - pSrc[2u * i3]; |
| <a name="l00428"></a>00428 |
| <a name="l00429"></a>00429 <span class="comment">/* xc' = (xa-xb+xc-xd)co2 + (ya-yb+yc-yd)(si2) */</span> |
| <a name="l00430"></a>00430 pSrc[2u * i1] = r1; |
| <a name="l00431"></a>00431 <span class="comment">/* yc' = (ya-yb+yc-yd)co2 - (xa-xb+xc-xd)(si2) */</span> |
| <a name="l00432"></a>00432 pSrc[(2u * i1) + 1u] = s1; |
| <a name="l00433"></a>00433 |
| <a name="l00434"></a>00434 <span class="comment">/* (xa+yb-xc-yd) */</span> |
| <a name="l00435"></a>00435 r1 = r2 + t1; |
| <a name="l00436"></a>00436 <span class="comment">/* (xa-yb-xc+yd) */</span> |
| <a name="l00437"></a>00437 r2 = r2 - t1; |
| <a name="l00438"></a>00438 |
| <a name="l00439"></a>00439 <span class="comment">/* (ya-xb-yc+xd) */</span> |
| <a name="l00440"></a>00440 s1 = s2 - t2; |
| <a name="l00441"></a>00441 <span class="comment">/* (ya+xb-yc-xd) */</span> |
| <a name="l00442"></a>00442 s2 = s2 + t2; |
| <a name="l00443"></a>00443 |
| <a name="l00444"></a>00444 <span class="comment">/* xb' = (xa+yb-xc-yd)co1 + (ya-xb-yc+xd)(si1) */</span> |
| <a name="l00445"></a>00445 pSrc[2u * i2] = r1; |
| <a name="l00446"></a>00446 <span class="comment">/* yb' = (ya-xb-yc+xd)co1 - (xa+yb-xc-yd)(si1) */</span> |
| <a name="l00447"></a>00447 pSrc[(2u * i2) + 1u] = s1; |
| <a name="l00448"></a>00448 |
| <a name="l00449"></a>00449 <span class="comment">/* xd' = (xa-yb-xc+yd)co3 + (ya+xb-yc-xd)(si3) */</span> |
| <a name="l00450"></a>00450 pSrc[2u * i3] = r2; |
| <a name="l00451"></a>00451 <span class="comment">/* yd' = (ya+xb-yc-xd)co3 - (xa-yb-xc+yd)(si3) */</span> |
| <a name="l00452"></a>00452 pSrc[(2u * i3) + 1u] = s2; |
| <a name="l00453"></a>00453 |
| <a name="l00454"></a>00454 |
| <a name="l00455"></a>00455 } |
| <a name="l00456"></a>00456 |
| <a name="l00457"></a>00457 <span class="comment">/* output is in 11.21(q21) format for the 1024 point */</span> |
| <a name="l00458"></a>00458 <span class="comment">/* output is in 9.23(q23) format for the 256 point */</span> |
| <a name="l00459"></a>00459 <span class="comment">/* output is in 7.25(q25) format for the 64 point */</span> |
| <a name="l00460"></a>00460 <span class="comment">/* output is in 5.27(q27) format for the 16 point */</span> |
| <a name="l00461"></a>00461 |
| <a name="l00462"></a>00462 <span class="comment">/* End of last stage process */</span> |
| <a name="l00463"></a>00463 |
| <a name="l00464"></a>00464 } |
| <a name="l00465"></a>00465 |
| <a name="l00466"></a>00466 |
| <a name="l00477"></a>00477 <span class="comment">/* </span> |
| <a name="l00478"></a>00478 <span class="comment">* Radix-4 IFFT algorithm used is : </span> |
| <a name="l00479"></a>00479 <span class="comment">* </span> |
| <a name="l00480"></a>00480 <span class="comment">* CIFFT uses same twiddle coefficients as CFFT Function </span> |
| <a name="l00481"></a>00481 <span class="comment">* x[k] = x[n] + (j)k * x[n + fftLen/4] + (-1)k * x[n+fftLen/2] + (-j)k * x[n+3*fftLen/4] </span> |
| <a name="l00482"></a>00482 <span class="comment">* </span> |
| <a name="l00483"></a>00483 <span class="comment">* </span> |
| <a name="l00484"></a>00484 <span class="comment">* IFFT is implemented with following changes in equations from FFT </span> |
| <a name="l00485"></a>00485 <span class="comment">* </span> |
| <a name="l00486"></a>00486 <span class="comment">* Input real and imaginary data: </span> |
| <a name="l00487"></a>00487 <span class="comment">* x(n) = xa + j * ya </span> |
| <a name="l00488"></a>00488 <span class="comment">* x(n+N/4 ) = xb + j * yb </span> |
| <a name="l00489"></a>00489 <span class="comment">* x(n+N/2 ) = xc + j * yc </span> |
| <a name="l00490"></a>00490 <span class="comment">* x(n+3N 4) = xd + j * yd </span> |
| <a name="l00491"></a>00491 <span class="comment">* </span> |
| <a name="l00492"></a>00492 <span class="comment">* </span> |
| <a name="l00493"></a>00493 <span class="comment">* Output real and imaginary data: </span> |
| <a name="l00494"></a>00494 <span class="comment">* x(4r) = xa'+ j * ya' </span> |
| <a name="l00495"></a>00495 <span class="comment">* x(4r+1) = xb'+ j * yb' </span> |
| <a name="l00496"></a>00496 <span class="comment">* x(4r+2) = xc'+ j * yc' </span> |
| <a name="l00497"></a>00497 <span class="comment">* x(4r+3) = xd'+ j * yd' </span> |
| <a name="l00498"></a>00498 <span class="comment">* </span> |
| <a name="l00499"></a>00499 <span class="comment">* </span> |
| <a name="l00500"></a>00500 <span class="comment">* Twiddle factors for radix-4 IFFT: </span> |
| <a name="l00501"></a>00501 <span class="comment">* Wn = co1 + j * (si1) </span> |
| <a name="l00502"></a>00502 <span class="comment">* W2n = co2 + j * (si2) </span> |
| <a name="l00503"></a>00503 <span class="comment">* W3n = co3 + j * (si3) </span> |
| <a name="l00504"></a>00504 <span class="comment"> </span> |
| <a name="l00505"></a>00505 <span class="comment">* The real and imaginary output values for the radix-4 butterfly are </span> |
| <a name="l00506"></a>00506 <span class="comment">* xa' = xa + xb + xc + xd </span> |
| <a name="l00507"></a>00507 <span class="comment">* ya' = ya + yb + yc + yd </span> |
| <a name="l00508"></a>00508 <span class="comment">* xb' = (xa-yb-xc+yd)* co1 - (ya+xb-yc-xd)* (si1) </span> |
| <a name="l00509"></a>00509 <span class="comment">* yb' = (ya+xb-yc-xd)* co1 + (xa-yb-xc+yd)* (si1) </span> |
| <a name="l00510"></a>00510 <span class="comment">* xc' = (xa-xb+xc-xd)* co2 - (ya-yb+yc-yd)* (si2) </span> |
| <a name="l00511"></a>00511 <span class="comment">* yc' = (ya-yb+yc-yd)* co2 + (xa-xb+xc-xd)* (si2) </span> |
| <a name="l00512"></a>00512 <span class="comment">* xd' = (xa+yb-xc-yd)* co3 - (ya-xb-yc+xd)* (si3) </span> |
| <a name="l00513"></a>00513 <span class="comment">* yd' = (ya-xb-yc+xd)* co3 + (xa+yb-xc-yd)* (si3) </span> |
| <a name="l00514"></a>00514 <span class="comment">* </span> |
| <a name="l00515"></a>00515 <span class="comment">*/</span> |
| <a name="l00516"></a>00516 |
| <a name="l00517"></a><a class="code" href="arm__math_8h.html#ac9c7c553114c1201a3a987a11b8a6d01">00517</a> <span class="keywordtype">void</span> <a class="code" href="arm__cfft__radix4__q31_8c.html#ac9c7c553114c1201a3a987a11b8a6d01" title="Core function for the Q31 CIFFT butterfly process.">arm_radix4_butterfly_inverse_q31</a>( |
| <a name="l00518"></a>00518 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> * pSrc, |
| <a name="l00519"></a>00519 uint32_t fftLen, |
| <a name="l00520"></a>00520 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> * pCoef, |
| <a name="l00521"></a>00521 uint32_t twidCoefModifier) |
| <a name="l00522"></a>00522 { |
| <a name="l00523"></a>00523 uint32_t n1, n2, ia1, ia2, ia3, i0, i1, i2, i3, j, k; |
| <a name="l00524"></a>00524 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> t1, t2, r1, r2, s1, s2, co1, co2, co3, si1, si2, si3; |
| <a name="l00525"></a>00525 |
| <a name="l00526"></a>00526 <span class="comment">/* input is be 1.31(q31) format for all FFT sizes */</span> |
| <a name="l00527"></a>00527 <span class="comment">/* Total process is divided into three stages */</span> |
| <a name="l00528"></a>00528 <span class="comment">/* process first stage, middle stages, & last stage */</span> |
| <a name="l00529"></a>00529 |
| <a name="l00530"></a>00530 <span class="comment">/* Start of first stage process */</span> |
| <a name="l00531"></a>00531 |
| <a name="l00532"></a>00532 <span class="comment">/* Initializations for the first stage */</span> |
| <a name="l00533"></a>00533 n2 = fftLen; |
| <a name="l00534"></a>00534 n1 = n2; |
| <a name="l00535"></a>00535 <span class="comment">/* n2 = fftLen/4 */</span> |
| <a name="l00536"></a>00536 n2 >>= 2u; |
| <a name="l00537"></a>00537 i0 = 0u; |
| <a name="l00538"></a>00538 ia1 = 0u; |
| <a name="l00539"></a>00539 |
| <a name="l00540"></a>00540 j = n2; |
| <a name="l00541"></a>00541 |
| <a name="l00542"></a>00542 <span class="keywordflow">do</span> |
| <a name="l00543"></a>00543 { |
| <a name="l00544"></a>00544 |
| <a name="l00545"></a>00545 <span class="comment">/* input is in 1.31(q31) format and provide 4 guard bits for the input */</span> |
| <a name="l00546"></a>00546 |
| <a name="l00547"></a>00547 <span class="comment">/* index calculation for the input as, */</span> |
| <a name="l00548"></a>00548 <span class="comment">/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2u], pSrc[i0 + 3fftLen/4] */</span> |
| <a name="l00549"></a>00549 i1 = i0 + n2; |
| <a name="l00550"></a>00550 i2 = i1 + n2; |
| <a name="l00551"></a>00551 i3 = i2 + n2; |
| <a name="l00552"></a>00552 |
| <a name="l00553"></a>00553 <span class="comment">/* Butterfly implementation */</span> |
| <a name="l00554"></a>00554 <span class="comment">/* xa + xc */</span> |
| <a name="l00555"></a>00555 r1 = (pSrc[2u * i0] >> 4u) + (pSrc[2u * i2] >> 4u); |
| <a name="l00556"></a>00556 <span class="comment">/* xa - xc */</span> |
| <a name="l00557"></a>00557 r2 = (pSrc[2u * i0] >> 4u) - (pSrc[2u * i2] >> 4u); |
| <a name="l00558"></a>00558 |
| <a name="l00559"></a>00559 <span class="comment">/* ya + yc */</span> |
| <a name="l00560"></a>00560 s1 = (pSrc[(2u * i0) + 1u] >> 4u) + (pSrc[(2u * i2) + 1u] >> 4u); |
| <a name="l00561"></a>00561 <span class="comment">/* ya - yc */</span> |
| <a name="l00562"></a>00562 s2 = (pSrc[(2u * i0) + 1u] >> 4u) - (pSrc[(2u * i2) + 1u] >> 4u); |
| <a name="l00563"></a>00563 |
| <a name="l00564"></a>00564 <span class="comment">/* xb + xd */</span> |
| <a name="l00565"></a>00565 t1 = (pSrc[2u * i1] >> 4u) + (pSrc[2u * i3] >> 4u); |
| <a name="l00566"></a>00566 |
| <a name="l00567"></a>00567 <span class="comment">/* xa' = xa + xb + xc + xd */</span> |
| <a name="l00568"></a>00568 pSrc[2u * i0] = (r1 + t1); |
| <a name="l00569"></a>00569 <span class="comment">/* (xa + xc) - (xb + xd) */</span> |
| <a name="l00570"></a>00570 r1 = r1 - t1; |
| <a name="l00571"></a>00571 <span class="comment">/* yb + yd */</span> |
| <a name="l00572"></a>00572 t2 = (pSrc[(2u * i1) + 1u] >> 4u) + (pSrc[(2u * i3) + 1u] >> 4u); |
| <a name="l00573"></a>00573 <span class="comment">/* ya' = ya + yb + yc + yd */</span> |
| <a name="l00574"></a>00574 pSrc[(2u * i0) + 1u] = (s1 + t2); |
| <a name="l00575"></a>00575 |
| <a name="l00576"></a>00576 <span class="comment">/* (ya + yc) - (yb + yd) */</span> |
| <a name="l00577"></a>00577 s1 = s1 - t2; |
| <a name="l00578"></a>00578 |
| <a name="l00579"></a>00579 <span class="comment">/* yb - yd */</span> |
| <a name="l00580"></a>00580 t1 = (pSrc[(2u * i1) + 1u] >> 4u) - (pSrc[(2u * i3) + 1u] >> 4u); |
| <a name="l00581"></a>00581 <span class="comment">/* xb - xd */</span> |
| <a name="l00582"></a>00582 t2 = (pSrc[2u * i1] >> 4u) - (pSrc[2u * i3] >> 4u); |
| <a name="l00583"></a>00583 |
| <a name="l00584"></a>00584 <span class="comment">/* index calculation for the coefficients */</span> |
| <a name="l00585"></a>00585 ia2 = 2u * ia1; |
| <a name="l00586"></a>00586 co2 = pCoef[ia2 * 2u]; |
| <a name="l00587"></a>00587 si2 = pCoef[(ia2 * 2u) + 1u]; |
| <a name="l00588"></a>00588 |
| <a name="l00589"></a>00589 <span class="comment">/* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */</span> |
| <a name="l00590"></a>00590 pSrc[2u * i1] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * co2) >> 32)) - |
| <a name="l00591"></a>00591 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * si2) >> 32))) << 1u; |
| <a name="l00592"></a>00592 |
| <a name="l00593"></a>00593 <span class="comment">/* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */</span> |
| <a name="l00594"></a>00594 pSrc[2u * i1 + 1u] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * co2) >> 32)) + |
| <a name="l00595"></a>00595 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * si2) >> 32))) << 1u; |
| <a name="l00596"></a>00596 |
| <a name="l00597"></a>00597 <span class="comment">/* (xa - xc) - (yb - yd) */</span> |
| <a name="l00598"></a>00598 r1 = r2 - t1; |
| <a name="l00599"></a>00599 <span class="comment">/* (xa - xc) + (yb - yd) */</span> |
| <a name="l00600"></a>00600 r2 = r2 + t1; |
| <a name="l00601"></a>00601 |
| <a name="l00602"></a>00602 <span class="comment">/* (ya - yc) + (xb - xd) */</span> |
| <a name="l00603"></a>00603 s1 = s2 + t2; |
| <a name="l00604"></a>00604 <span class="comment">/* (ya - yc) - (xb - xd) */</span> |
| <a name="l00605"></a>00605 s2 = s2 - t2; |
| <a name="l00606"></a>00606 |
| <a name="l00607"></a>00607 co1 = pCoef[ia1 * 2u]; |
| <a name="l00608"></a>00608 si1 = pCoef[(ia1 * 2u) + 1u]; |
| <a name="l00609"></a>00609 |
| <a name="l00610"></a>00610 <span class="comment">/* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */</span> |
| <a name="l00611"></a>00611 pSrc[2u * i2] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * co1) >> 32)) - |
| <a name="l00612"></a>00612 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * si1) >> 32))) << 1u; |
| <a name="l00613"></a>00613 |
| <a name="l00614"></a>00614 <span class="comment">/* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */</span> |
| <a name="l00615"></a>00615 pSrc[(2u * i2) + 1u] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * co1) >> 32)) + |
| <a name="l00616"></a>00616 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * si1) >> 32))) << 1u; |
| <a name="l00617"></a>00617 |
| <a name="l00618"></a>00618 <span class="comment">/* index calculation for the coefficients */</span> |
| <a name="l00619"></a>00619 ia3 = 3u * ia1; |
| <a name="l00620"></a>00620 co3 = pCoef[ia3 * 2u]; |
| <a name="l00621"></a>00621 si3 = pCoef[(ia3 * 2u) + 1u]; |
| <a name="l00622"></a>00622 |
| <a name="l00623"></a>00623 <span class="comment">/* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */</span> |
| <a name="l00624"></a>00624 pSrc[2u * i3] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r2 * co3) >> 32)) - |
| <a name="l00625"></a>00625 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s2 * si3) >> 32))) << 1u; |
| <a name="l00626"></a>00626 |
| <a name="l00627"></a>00627 <span class="comment">/* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */</span> |
| <a name="l00628"></a>00628 pSrc[(2u * i3) + 1u] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s2 * co3) >> 32)) + |
| <a name="l00629"></a>00629 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r2 * si3) >> 32))) << 1u; |
| <a name="l00630"></a>00630 |
| <a name="l00631"></a>00631 <span class="comment">/* Twiddle coefficients index modifier */</span> |
| <a name="l00632"></a>00632 ia1 = ia1 + twidCoefModifier; |
| <a name="l00633"></a>00633 |
| <a name="l00634"></a>00634 <span class="comment">/* Updating input index */</span> |
| <a name="l00635"></a>00635 i0 = i0 + 1u; |
| <a name="l00636"></a>00636 |
| <a name="l00637"></a>00637 } <span class="keywordflow">while</span>(--j); |
| <a name="l00638"></a>00638 |
| <a name="l00639"></a>00639 <span class="comment">/* data is in 5.27(q27) format */</span> |
| <a name="l00640"></a>00640 <span class="comment">/* each stage provides two down scaling of the input */</span> |
| <a name="l00641"></a>00641 |
| <a name="l00642"></a>00642 |
| <a name="l00643"></a>00643 <span class="comment">/* Start of Middle stages process */</span> |
| <a name="l00644"></a>00644 |
| <a name="l00645"></a>00645 twidCoefModifier <<= 2u; |
| <a name="l00646"></a>00646 |
| <a name="l00647"></a>00647 <span class="comment">/* Calculation of second stage to excluding last stage */</span> |
| <a name="l00648"></a>00648 <span class="keywordflow">for</span> (k = fftLen / 4u; k > 4u; k >>= 2u) |
| <a name="l00649"></a>00649 { |
| <a name="l00650"></a>00650 <span class="comment">/* Initializations for the first stage */</span> |
| <a name="l00651"></a>00651 n1 = n2; |
| <a name="l00652"></a>00652 n2 >>= 2u; |
| <a name="l00653"></a>00653 ia1 = 0u; |
| <a name="l00654"></a>00654 |
| <a name="l00655"></a>00655 <span class="keywordflow">for</span> (j = 0; j <= (n2 - 1u); j++) |
| <a name="l00656"></a>00656 { |
| <a name="l00657"></a>00657 <span class="comment">/* index calculation for the coefficients */</span> |
| <a name="l00658"></a>00658 ia2 = ia1 + ia1; |
| <a name="l00659"></a>00659 ia3 = ia2 + ia1; |
| <a name="l00660"></a>00660 co1 = pCoef[ia1 * 2u]; |
| <a name="l00661"></a>00661 si1 = pCoef[(ia1 * 2u) + 1u]; |
| <a name="l00662"></a>00662 co2 = pCoef[ia2 * 2u]; |
| <a name="l00663"></a>00663 si2 = pCoef[(ia2 * 2u) + 1u]; |
| <a name="l00664"></a>00664 co3 = pCoef[ia3 * 2u]; |
| <a name="l00665"></a>00665 si3 = pCoef[(ia3 * 2u) + 1u]; |
| <a name="l00666"></a>00666 <span class="comment">/* Twiddle coefficients index modifier */</span> |
| <a name="l00667"></a>00667 ia1 = ia1 + twidCoefModifier; |
| <a name="l00668"></a>00668 |
| <a name="l00669"></a>00669 <span class="keywordflow">for</span> (i0 = j; i0 < fftLen; i0 += n1) |
| <a name="l00670"></a>00670 { |
| <a name="l00671"></a>00671 <span class="comment">/* index calculation for the input as, */</span> |
| <a name="l00672"></a>00672 <span class="comment">/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2u], pSrc[i0 + 3fftLen/4] */</span> |
| <a name="l00673"></a>00673 i1 = i0 + n2; |
| <a name="l00674"></a>00674 i2 = i1 + n2; |
| <a name="l00675"></a>00675 i3 = i2 + n2; |
| <a name="l00676"></a>00676 |
| <a name="l00677"></a>00677 <span class="comment">/* Butterfly implementation */</span> |
| <a name="l00678"></a>00678 <span class="comment">/* xa + xc */</span> |
| <a name="l00679"></a>00679 r1 = pSrc[2u * i0] + pSrc[2u * i2]; |
| <a name="l00680"></a>00680 <span class="comment">/* xa - xc */</span> |
| <a name="l00681"></a>00681 r2 = pSrc[2u * i0] - pSrc[2u * i2]; |
| <a name="l00682"></a>00682 |
| <a name="l00683"></a>00683 <span class="comment">/* ya + yc */</span> |
| <a name="l00684"></a>00684 s1 = pSrc[(2u * i0) + 1u] + pSrc[(2u * i2) + 1u]; |
| <a name="l00685"></a>00685 <span class="comment">/* ya - yc */</span> |
| <a name="l00686"></a>00686 s2 = pSrc[(2u * i0) + 1u] - pSrc[(2u * i2) + 1u]; |
| <a name="l00687"></a>00687 |
| <a name="l00688"></a>00688 <span class="comment">/* xb + xd */</span> |
| <a name="l00689"></a>00689 t1 = pSrc[2u * i1] + pSrc[2u * i3]; |
| <a name="l00690"></a>00690 |
| <a name="l00691"></a>00691 <span class="comment">/* xa' = xa + xb + xc + xd */</span> |
| <a name="l00692"></a>00692 pSrc[2u * i0] = (r1 + t1) >> 2u; |
| <a name="l00693"></a>00693 <span class="comment">/* xa + xc -(xb + xd) */</span> |
| <a name="l00694"></a>00694 r1 = r1 - t1; |
| <a name="l00695"></a>00695 <span class="comment">/* yb + yd */</span> |
| <a name="l00696"></a>00696 t2 = pSrc[(2u * i1) + 1u] + pSrc[(2u * i3) + 1u]; |
| <a name="l00697"></a>00697 <span class="comment">/* ya' = ya + yb + yc + yd */</span> |
| <a name="l00698"></a>00698 pSrc[(2u * i0) + 1u] = (s1 + t2) >> 2u; |
| <a name="l00699"></a>00699 |
| <a name="l00700"></a>00700 <span class="comment">/* (ya + yc) - (yb + yd) */</span> |
| <a name="l00701"></a>00701 s1 = s1 - t2; |
| <a name="l00702"></a>00702 |
| <a name="l00703"></a>00703 <span class="comment">/* (yb - yd) */</span> |
| <a name="l00704"></a>00704 t1 = pSrc[(2u * i1) + 1u] - pSrc[(2u * i3) + 1u]; |
| <a name="l00705"></a>00705 <span class="comment">/* (xb - xd) */</span> |
| <a name="l00706"></a>00706 t2 = pSrc[2u * i1] - pSrc[2u * i3]; |
| <a name="l00707"></a>00707 |
| <a name="l00708"></a>00708 <span class="comment">/* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */</span> |
| <a name="l00709"></a>00709 pSrc[2u * i1] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * co2) >> 32u)) - |
| <a name="l00710"></a>00710 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * si2) >> 32u))) >> 1u; |
| <a name="l00711"></a>00711 |
| <a name="l00712"></a>00712 <span class="comment">/* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */</span> |
| <a name="l00713"></a>00713 pSrc[(2u * i1) + 1u] = |
| <a name="l00714"></a>00714 (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * co2) >> 32u)) + |
| <a name="l00715"></a>00715 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * si2) >> 32u))) >> 1u; |
| <a name="l00716"></a>00716 |
| <a name="l00717"></a>00717 <span class="comment">/* (xa - xc) - (yb - yd) */</span> |
| <a name="l00718"></a>00718 r1 = r2 - t1; |
| <a name="l00719"></a>00719 <span class="comment">/* (xa - xc) + (yb - yd) */</span> |
| <a name="l00720"></a>00720 r2 = r2 + t1; |
| <a name="l00721"></a>00721 |
| <a name="l00722"></a>00722 <span class="comment">/* (ya - yc) + (xb - xd) */</span> |
| <a name="l00723"></a>00723 s1 = s2 + t2; |
| <a name="l00724"></a>00724 <span class="comment">/* (ya - yc) - (xb - xd) */</span> |
| <a name="l00725"></a>00725 s2 = s2 - t2; |
| <a name="l00726"></a>00726 |
| <a name="l00727"></a>00727 <span class="comment">/* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */</span> |
| <a name="l00728"></a>00728 pSrc[2u * i2] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * co1) >> 32)) - |
| <a name="l00729"></a>00729 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * si1) >> 32))) >> 1u; |
| <a name="l00730"></a>00730 |
| <a name="l00731"></a>00731 <span class="comment">/* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */</span> |
| <a name="l00732"></a>00732 pSrc[(2u * i2) + 1u] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s1 * co1) >> 32)) + |
| <a name="l00733"></a>00733 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r1 * si1) >> 32))) >> 1u; |
| <a name="l00734"></a>00734 |
| <a name="l00735"></a>00735 <span class="comment">/* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */</span> |
| <a name="l00736"></a>00736 pSrc[(2u * i3)] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r2 * co3) >> 32)) - |
| <a name="l00737"></a>00737 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s2 * si3) >> 32))) >> 1u; |
| <a name="l00738"></a>00738 |
| <a name="l00739"></a>00739 <span class="comment">/* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */</span> |
| <a name="l00740"></a>00740 pSrc[(2u * i3) + 1u] = (((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) s2 * co3) >> 32)) + |
| <a name="l00741"></a>00741 ((int32_t) (((<a class="code" href="arm__math_8h.html#a5aea1cb12fc02d9d44c8abf217eaa5c6" title="64-bit fractional data type in 1.63 format.">q63_t</a>) r2 * si3) >> 32))) >> 1u; |
| <a name="l00742"></a>00742 } |
| <a name="l00743"></a>00743 } |
| <a name="l00744"></a>00744 twidCoefModifier <<= 2u; |
| <a name="l00745"></a>00745 } |
| <a name="l00746"></a>00746 |
| <a name="l00747"></a>00747 <span class="comment">/* End of Middle stages process */</span> |
| <a name="l00748"></a>00748 |
| <a name="l00749"></a>00749 <span class="comment">/* data is in 11.21(q21) format for the 1024 point as there are 3 middle stages */</span> |
| <a name="l00750"></a>00750 <span class="comment">/* data is in 9.23(q23) format for the 256 point as there are 2 middle stages */</span> |
| <a name="l00751"></a>00751 <span class="comment">/* data is in 7.25(q25) format for the 64 point as there are 1 middle stage */</span> |
| <a name="l00752"></a>00752 <span class="comment">/* data is in 5.27(q27) format for the 16 point as there are no middle stages */</span> |
| <a name="l00753"></a>00753 |
| <a name="l00754"></a>00754 |
| <a name="l00755"></a>00755 <span class="comment">/* Start of last stage process */</span> |
| <a name="l00756"></a>00756 |
| <a name="l00757"></a>00757 |
| <a name="l00758"></a>00758 <span class="comment">/* Initializations of last stage */</span> |
| <a name="l00759"></a>00759 n1 = n2; |
| <a name="l00760"></a>00760 n2 >>= 2u; |
| <a name="l00761"></a>00761 |
| <a name="l00762"></a>00762 <span class="comment">/* Calculations of last stage */</span> |
| <a name="l00763"></a>00763 <span class="keywordflow">for</span> (i0 = 0u; i0 <= (fftLen - n1); i0 += n1) |
| <a name="l00764"></a>00764 { |
| <a name="l00765"></a>00765 <span class="comment">/* index calculation for the input as, */</span> |
| <a name="l00766"></a>00766 <span class="comment">/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2u], pSrc[i0 + 3fftLen/4] */</span> |
| <a name="l00767"></a>00767 i1 = i0 + n2; |
| <a name="l00768"></a>00768 i2 = i1 + n2; |
| <a name="l00769"></a>00769 i3 = i2 + n2; |
| <a name="l00770"></a>00770 |
| <a name="l00771"></a>00771 <span class="comment">/* Butterfly implementation */</span> |
| <a name="l00772"></a>00772 <span class="comment">/* xa + xc */</span> |
| <a name="l00773"></a>00773 r1 = pSrc[2u * i0] + pSrc[2u * i2]; |
| <a name="l00774"></a>00774 <span class="comment">/* xa - xc */</span> |
| <a name="l00775"></a>00775 r2 = pSrc[2u * i0] - pSrc[2u * i2]; |
| <a name="l00776"></a>00776 |
| <a name="l00777"></a>00777 <span class="comment">/* ya + yc */</span> |
| <a name="l00778"></a>00778 s1 = pSrc[(2u * i0) + 1u] + pSrc[(2u * i2) + 1u]; |
| <a name="l00779"></a>00779 <span class="comment">/* ya - yc */</span> |
| <a name="l00780"></a>00780 s2 = pSrc[(2u * i0) + 1u] - pSrc[(2u * i2) + 1u]; |
| <a name="l00781"></a>00781 |
| <a name="l00782"></a>00782 <span class="comment">/* xc + xd */</span> |
| <a name="l00783"></a>00783 t1 = pSrc[2u * i1] + pSrc[2u * i3]; |
| <a name="l00784"></a>00784 <span class="comment">/* xa' = xa + xb + xc + xd */</span> |
| <a name="l00785"></a>00785 pSrc[2u * i0] = (r1 + t1); |
| <a name="l00786"></a>00786 <span class="comment">/* (xa + xb) - (xc + xd) */</span> |
| <a name="l00787"></a>00787 r1 = r1 - t1; |
| <a name="l00788"></a>00788 |
| <a name="l00789"></a>00789 <span class="comment">/* yb + yd */</span> |
| <a name="l00790"></a>00790 t2 = pSrc[(2u * i1) + 1u] + pSrc[(2u * i3) + 1u]; |
| <a name="l00791"></a>00791 <span class="comment">/* ya' = ya + yb + yc + yd */</span> |
| <a name="l00792"></a>00792 pSrc[(2u * i0) + 1u] = (s1 + t2); |
| <a name="l00793"></a>00793 <span class="comment">/* (ya + yc) - (yb + yd) */</span> |
| <a name="l00794"></a>00794 s1 = s1 - t2; |
| <a name="l00795"></a>00795 |
| <a name="l00796"></a>00796 <span class="comment">/* (yb-yd) */</span> |
| <a name="l00797"></a>00797 t1 = pSrc[(2u * i1) + 1u] - pSrc[(2u * i3) + 1u]; |
| <a name="l00798"></a>00798 <span class="comment">/* (xb-xd) */</span> |
| <a name="l00799"></a>00799 t2 = pSrc[2u * i1] - pSrc[2u * i3]; |
| <a name="l00800"></a>00800 |
| <a name="l00801"></a>00801 <span class="comment">/* xc' = (xa-xb+xc-xd)co2 - (ya-yb+yc-yd)(si2) */</span> |
| <a name="l00802"></a>00802 pSrc[2u * i1] = r1; |
| <a name="l00803"></a>00803 <span class="comment">/* yc' = (ya-yb+yc-yd)co2 + (xa-xb+xc-xd)(si2) */</span> |
| <a name="l00804"></a>00804 pSrc[(2u * i1) + 1u] = s1; |
| <a name="l00805"></a>00805 |
| <a name="l00806"></a>00806 <span class="comment">/* (xa - xc) - (yb-yd) */</span> |
| <a name="l00807"></a>00807 r1 = r2 - t1; |
| <a name="l00808"></a>00808 |
| <a name="l00809"></a>00809 <span class="comment">/* (xa - xc) + (yb-yd) */</span> |
| <a name="l00810"></a>00810 r2 = r2 + t1; |
| <a name="l00811"></a>00811 |
| <a name="l00812"></a>00812 <span class="comment">/* (ya - yc) + (xb-xd) */</span> |
| <a name="l00813"></a>00813 s1 = s2 + t2; |
| <a name="l00814"></a>00814 |
| <a name="l00815"></a>00815 <span class="comment">/* (ya - yc) - (xb-xd) */</span> |
| <a name="l00816"></a>00816 s2 = s2 - t2; |
| <a name="l00817"></a>00817 |
| <a name="l00818"></a>00818 <span class="comment">/* xb' = (xa+yb-xc-yd)co1 - (ya-xb-yc+xd)(si1) */</span> |
| <a name="l00819"></a>00819 pSrc[2u * i2] = r1; |
| <a name="l00820"></a>00820 <span class="comment">/* yb' = (ya-xb-yc+xd)co1 + (xa+yb-xc-yd)(si1) */</span> |
| <a name="l00821"></a>00821 pSrc[(2u * i2) + 1u] = s1; |
| <a name="l00822"></a>00822 |
| <a name="l00823"></a>00823 <span class="comment">/* xd' = (xa-yb-xc+yd)co3 - (ya+xb-yc-xd)(si3) */</span> |
| <a name="l00824"></a>00824 pSrc[2u * i3] = r2; |
| <a name="l00825"></a>00825 <span class="comment">/* yd' = (ya+xb-yc-xd)co3 + (xa-yb-xc+yd)(si3) */</span> |
| <a name="l00826"></a>00826 pSrc[(2u * i3) + 1u] = s2; |
| <a name="l00827"></a>00827 |
| <a name="l00828"></a>00828 } |
| <a name="l00829"></a>00829 |
| <a name="l00830"></a>00830 <span class="comment">/* output is in 11.21(q21) format for the 1024 point */</span> |
| <a name="l00831"></a>00831 <span class="comment">/* output is in 9.23(q23) format for the 256 point */</span> |
| <a name="l00832"></a>00832 <span class="comment">/* output is in 7.25(q25) format for the 64 point */</span> |
| <a name="l00833"></a>00833 <span class="comment">/* output is in 5.27(q27) format for the 16 point */</span> |
| <a name="l00834"></a>00834 |
| <a name="l00835"></a>00835 <span class="comment">/* End of last stage process */</span> |
| <a name="l00836"></a>00836 } |
| <a name="l00837"></a>00837 |
| <a name="l00838"></a>00838 |
| <a name="l00839"></a>00839 <span class="comment">/* </span> |
| <a name="l00840"></a>00840 <span class="comment"> * @brief In-place bit reversal function. </span> |
| <a name="l00841"></a>00841 <span class="comment"> * @param[in, out] *pSrc points to the in-place buffer of Q31 data type. </span> |
| <a name="l00842"></a>00842 <span class="comment"> * @param[in] fftLen length of the FFT. </span> |
| <a name="l00843"></a>00843 <span class="comment"> * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table </span> |
| <a name="l00844"></a>00844 <span class="comment"> * @param[in] *pBitRevTab points to bit reversal table. </span> |
| <a name="l00845"></a>00845 <span class="comment"> * @return none. </span> |
| <a name="l00846"></a>00846 <span class="comment"> */</span> |
| <a name="l00847"></a>00847 |
| <a name="l00848"></a><a class="code" href="arm__math_8h.html#a3fab577d25c3a517973c8c214f66f268">00848</a> <span class="keywordtype">void</span> <a class="code" href="arm__cfft__radix4__q31_8c.html#a27618705158b5c42db5fb0a381f8efc1" title="In-place bit reversal function.">arm_bitreversal_q31</a>( |
| <a name="l00849"></a>00849 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> * pSrc, |
| <a name="l00850"></a>00850 uint32_t fftLen, |
| <a name="l00851"></a>00851 uint16_t bitRevFactor, |
| <a name="l00852"></a>00852 uint16_t * pBitRevTable) |
| <a name="l00853"></a>00853 { |
| <a name="l00854"></a>00854 uint32_t fftLenBy2, fftLenBy2p1, i, j; |
| <a name="l00855"></a>00855 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> in; |
| <a name="l00856"></a>00856 |
| <a name="l00857"></a>00857 <span class="comment">/* Initializations */</span> |
| <a name="l00858"></a>00858 j = 0u; |
| <a name="l00859"></a>00859 fftLenBy2 = fftLen / 2u; |
| <a name="l00860"></a>00860 fftLenBy2p1 = (fftLen / 2u) + 1u; |
| <a name="l00861"></a>00861 |
| <a name="l00862"></a>00862 <span class="comment">/* Bit Reversal Implementation */</span> |
| <a name="l00863"></a>00863 <span class="keywordflow">for</span> (i = 0u; i <= (fftLenBy2 - 2u); i += 2u) |
| <a name="l00864"></a>00864 { |
| <a name="l00865"></a>00865 <span class="keywordflow">if</span>(i < j) |
| <a name="l00866"></a>00866 { |
| <a name="l00867"></a>00867 <span class="comment">/* pSrc[i] <-> pSrc[j]; */</span> |
| <a name="l00868"></a>00868 in = pSrc[2u * i]; |
| <a name="l00869"></a>00869 pSrc[2u * i] = pSrc[2u * j]; |
| <a name="l00870"></a>00870 pSrc[2u * j] = in; |
| <a name="l00871"></a>00871 |
| <a name="l00872"></a>00872 <span class="comment">/* pSrc[i+1u] <-> pSrc[j+1u] */</span> |
| <a name="l00873"></a>00873 in = pSrc[(2u * i) + 1u]; |
| <a name="l00874"></a>00874 pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u]; |
| <a name="l00875"></a>00875 pSrc[(2u * j) + 1u] = in; |
| <a name="l00876"></a>00876 |
| <a name="l00877"></a>00877 <span class="comment">/* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */</span> |
| <a name="l00878"></a>00878 in = pSrc[2u * (i + fftLenBy2p1)]; |
| <a name="l00879"></a>00879 pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)]; |
| <a name="l00880"></a>00880 pSrc[2u * (j + fftLenBy2p1)] = in; |
| <a name="l00881"></a>00881 |
| <a name="l00882"></a>00882 <span class="comment">/* pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */</span> |
| <a name="l00883"></a>00883 in = pSrc[(2u * (i + fftLenBy2p1)) + 1u]; |
| <a name="l00884"></a>00884 pSrc[(2u * (i + fftLenBy2p1)) + 1u] = |
| <a name="l00885"></a>00885 pSrc[(2u * (j + fftLenBy2p1)) + 1u]; |
| <a name="l00886"></a>00886 pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in; |
| <a name="l00887"></a>00887 |
| <a name="l00888"></a>00888 } |
| <a name="l00889"></a>00889 |
| <a name="l00890"></a>00890 <span class="comment">/* pSrc[i+1u] <-> pSrc[j+1u] */</span> |
| <a name="l00891"></a>00891 in = pSrc[2u * (i + 1u)]; |
| <a name="l00892"></a>00892 pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)]; |
| <a name="l00893"></a>00893 pSrc[2u * (j + fftLenBy2)] = in; |
| <a name="l00894"></a>00894 |
| <a name="l00895"></a>00895 <span class="comment">/* pSrc[i+2u] <-> pSrc[j+2u] */</span> |
| <a name="l00896"></a>00896 in = pSrc[(2u * (i + 1u)) + 1u]; |
| <a name="l00897"></a>00897 pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u]; |
| <a name="l00898"></a>00898 pSrc[(2u * (j + fftLenBy2)) + 1u] = in; |
| <a name="l00899"></a>00899 |
| <a name="l00900"></a>00900 <span class="comment">/* Reading the index for the bit reversal */</span> |
| <a name="l00901"></a>00901 j = *pBitRevTable; |
| <a name="l00902"></a>00902 |
| <a name="l00903"></a>00903 <span class="comment">/* Updating the bit reversal index depending on the fft length */</span> |
| <a name="l00904"></a>00904 pBitRevTable += bitRevFactor; |
| <a name="l00905"></a>00905 } |
| <a name="l00906"></a>00906 } |
| </pre></div></div> |
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