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<a href="#func-members">Functions</a> </div>
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<div class="headertitle"><div class="title">Real FFT Functions<div class="ingroups"><a class="el" href="group__groupTransforms.html">Transform Functions</a></div></div></div>
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Content</h2></td></tr>
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<tr class="memitem:group__RealFFT__Table"><td class="memItemLeft" align="right" valign="top"> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__RealFFT__Table.html">Real FFT Tables</a></td></tr>
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Functions</h2></td></tr>
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<tr class="memitem:ga3df1766d230532bc068fc4ed69d0fcdc"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__RealFFT.html#ga3df1766d230532bc068fc4ed69d0fcdc">arm_rfft_f32</a> (const <a class="el" href="structarm__rfft__instance__f32.html">arm_rfft_instance_f32</a> *S, <a class="el" href="arm__math__types_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> *pSrc, <a class="el" href="arm__math__types_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> *pDst)</td></tr>
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<tr class="memdesc:ga3df1766d230532bc068fc4ed69d0fcdc"><td class="mdescLeft"> </td><td class="mdescRight">Processing function for the floating-point RFFT/RIFFT. Source buffer is modified by this function. <a href="group__RealFFT.html#ga3df1766d230532bc068fc4ed69d0fcdc">More...</a><br /></td></tr>
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<tr class="separator:ga3df1766d230532bc068fc4ed69d0fcdc"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:gaf018157c88626e83de3d9143f5273d18"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__RealFFT.html#gaf018157c88626e83de3d9143f5273d18">arm_rfft_fast_f16</a> (const <a class="el" href="structarm__rfft__fast__instance__f16.html">arm_rfft_fast_instance_f16</a> *S, float16_t *p, float16_t *pOut, uint8_t <a class="el" href="arm__fft__bin__example__f32_8c.html#a379ccb99013d369a41b49619083c16ef">ifftFlag</a>)</td></tr>
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<tr class="memdesc:gaf018157c88626e83de3d9143f5273d18"><td class="mdescLeft"> </td><td class="mdescRight">Processing function for the floating-point real FFT. <a href="group__RealFFT.html#gaf018157c88626e83de3d9143f5273d18">More...</a><br /></td></tr>
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<tr class="separator:gaf018157c88626e83de3d9143f5273d18"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:ga5d2ec62f3e35575eba467d09ddcd98b5"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__RealFFT.html#ga5d2ec62f3e35575eba467d09ddcd98b5">arm_rfft_fast_f32</a> (const <a class="el" href="structarm__rfft__fast__instance__f32.html">arm_rfft_fast_instance_f32</a> *S, <a class="el" href="arm__math__types_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> *p, <a class="el" href="arm__math__types_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> *pOut, uint8_t <a class="el" href="arm__fft__bin__example__f32_8c.html#a379ccb99013d369a41b49619083c16ef">ifftFlag</a>)</td></tr>
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<tr class="memdesc:ga5d2ec62f3e35575eba467d09ddcd98b5"><td class="mdescLeft"> </td><td class="mdescRight">Processing function for the floating-point real FFT. <a href="group__RealFFT.html#ga5d2ec62f3e35575eba467d09ddcd98b5">More...</a><br /></td></tr>
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<tr class="separator:ga5d2ec62f3e35575eba467d09ddcd98b5"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:gae3b00f039305039732f7364171da89fb"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__RealFFT.html#gae3b00f039305039732f7364171da89fb">arm_rfft_fast_f64</a> (<a class="el" href="structarm__rfft__fast__instance__f64.html">arm_rfft_fast_instance_f64</a> *S, <a class="el" href="arm__math__types_8h.html#ac55f3ae81b5bc9053760baacf57e47f4">float64_t</a> *p, <a class="el" href="arm__math__types_8h.html#ac55f3ae81b5bc9053760baacf57e47f4">float64_t</a> *pOut, uint8_t <a class="el" href="arm__fft__bin__example__f32_8c.html#a379ccb99013d369a41b49619083c16ef">ifftFlag</a>)</td></tr>
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<tr class="memdesc:gae3b00f039305039732f7364171da89fb"><td class="mdescLeft"> </td><td class="mdescRight">Processing function for the Double Precision floating-point real FFT. <a href="group__RealFFT.html#gae3b00f039305039732f7364171da89fb">More...</a><br /></td></tr>
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<tr class="separator:gae3b00f039305039732f7364171da89fb"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:gacc1c721dd5a690a4c90cfb0264058659"><td class="memItemLeft" align="right" valign="top"><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__RealFFT.html#gacc1c721dd5a690a4c90cfb0264058659">arm_rfft_fast_init_f16</a> (<a class="el" href="structarm__rfft__fast__instance__f16.html">arm_rfft_fast_instance_f16</a> *S, uint16_t fftLen)</td></tr>
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<tr class="memdesc:gacc1c721dd5a690a4c90cfb0264058659"><td class="mdescLeft"> </td><td class="mdescRight">Initialization function for the floating-point real FFT. <a href="group__RealFFT.html#gacc1c721dd5a690a4c90cfb0264058659">More...</a><br /></td></tr>
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<tr class="separator:gacc1c721dd5a690a4c90cfb0264058659"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:gac5fceb172551e7c11eb4d0e17ef15aa3"><td class="memItemLeft" align="right" valign="top"><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__RealFFT.html#gac5fceb172551e7c11eb4d0e17ef15aa3">arm_rfft_fast_init_f32</a> (<a class="el" href="structarm__rfft__fast__instance__f32.html">arm_rfft_fast_instance_f32</a> *S, uint16_t fftLen)</td></tr>
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<tr class="memdesc:gac5fceb172551e7c11eb4d0e17ef15aa3"><td class="mdescLeft"> </td><td class="mdescRight">Initialization function for the floating-point real FFT. <a href="group__RealFFT.html#gac5fceb172551e7c11eb4d0e17ef15aa3">More...</a><br /></td></tr>
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<tr class="separator:gac5fceb172551e7c11eb4d0e17ef15aa3"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:ga51ca806ce1aa56a231684add8d2820bb"><td class="memItemLeft" align="right" valign="top"><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__RealFFT.html#ga51ca806ce1aa56a231684add8d2820bb">arm_rfft_fast_init_f64</a> (<a class="el" href="structarm__rfft__fast__instance__f64.html">arm_rfft_fast_instance_f64</a> *S, uint16_t fftLen)</td></tr>
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<tr class="memdesc:ga51ca806ce1aa56a231684add8d2820bb"><td class="mdescLeft"> </td><td class="mdescRight">Initialization function for the Double Precision floating-point real FFT. <a href="group__RealFFT.html#ga51ca806ce1aa56a231684add8d2820bb">More...</a><br /></td></tr>
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<tr class="separator:ga51ca806ce1aa56a231684add8d2820bb"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:ga10717ee326bf50832ef1c25b85a23068"><td class="memItemLeft" align="right" valign="top"><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__RealFFT.html#ga10717ee326bf50832ef1c25b85a23068">arm_rfft_init_f32</a> (<a class="el" href="structarm__rfft__instance__f32.html">arm_rfft_instance_f32</a> *S, <a class="el" href="structarm__cfft__radix4__instance__f32.html">arm_cfft_radix4_instance_f32</a> *S_CFFT, uint32_t fftLenReal, uint32_t ifftFlagR, uint32_t bitReverseFlag)</td></tr>
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<tr class="memdesc:ga10717ee326bf50832ef1c25b85a23068"><td class="mdescLeft"> </td><td class="mdescRight">Initialization function for the floating-point RFFT/RIFFT. <a href="group__RealFFT.html#ga10717ee326bf50832ef1c25b85a23068">More...</a><br /></td></tr>
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<tr class="separator:ga10717ee326bf50832ef1c25b85a23068"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:ga053450cc600a55410ba5b5605e96245d"><td class="memItemLeft" align="right" valign="top"><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__RealFFT.html#ga053450cc600a55410ba5b5605e96245d">arm_rfft_init_q15</a> (<a class="el" href="structarm__rfft__instance__q15.html">arm_rfft_instance_q15</a> *S, uint32_t fftLenReal, uint32_t ifftFlagR, uint32_t bitReverseFlag)</td></tr>
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<tr class="memdesc:ga053450cc600a55410ba5b5605e96245d"><td class="mdescLeft"> </td><td class="mdescRight">Initialization function for the Q15 RFFT/RIFFT. <a href="group__RealFFT.html#ga053450cc600a55410ba5b5605e96245d">More...</a><br /></td></tr>
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<tr class="separator:ga053450cc600a55410ba5b5605e96245d"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:ga5abde938abbe72e95c5bab080eb33c45"><td class="memItemLeft" align="right" valign="top"><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__RealFFT.html#ga5abde938abbe72e95c5bab080eb33c45">arm_rfft_init_q31</a> (<a class="el" href="structarm__rfft__instance__q31.html">arm_rfft_instance_q31</a> *S, uint32_t fftLenReal, uint32_t ifftFlagR, uint32_t bitReverseFlag)</td></tr>
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<tr class="memdesc:ga5abde938abbe72e95c5bab080eb33c45"><td class="mdescLeft"> </td><td class="mdescRight">Initialization function for the Q31 RFFT/RIFFT. <a href="group__RealFFT.html#ga5abde938abbe72e95c5bab080eb33c45">More...</a><br /></td></tr>
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<tr class="separator:ga5abde938abbe72e95c5bab080eb33c45"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:ga00e615f5db21736ad5b27fb6146f3fc5"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__RealFFT.html#ga00e615f5db21736ad5b27fb6146f3fc5">arm_rfft_q15</a> (const <a class="el" href="structarm__rfft__instance__q15.html">arm_rfft_instance_q15</a> *S, <a class="el" href="arm__math__types_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> *pSrc, <a class="el" href="arm__math__types_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> *pDst)</td></tr>
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<tr class="memdesc:ga00e615f5db21736ad5b27fb6146f3fc5"><td class="mdescLeft"> </td><td class="mdescRight">Processing function for the Q15 RFFT/RIFFT. <a href="group__RealFFT.html#ga00e615f5db21736ad5b27fb6146f3fc5">More...</a><br /></td></tr>
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<tr class="separator:ga00e615f5db21736ad5b27fb6146f3fc5"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:gabaeab5646aeea9844e6d42ca8c73fe3a"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__RealFFT.html#gabaeab5646aeea9844e6d42ca8c73fe3a">arm_rfft_q31</a> (const <a class="el" href="structarm__rfft__instance__q31.html">arm_rfft_instance_q31</a> *S, <a class="el" href="arm__math__types_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> *pSrc, <a class="el" href="arm__math__types_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> *pDst)</td></tr>
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<tr class="memdesc:gabaeab5646aeea9844e6d42ca8c73fe3a"><td class="mdescLeft"> </td><td class="mdescRight">Processing function for the Q31 RFFT/RIFFT. <a href="group__RealFFT.html#gabaeab5646aeea9844e6d42ca8c73fe3a">More...</a><br /></td></tr>
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<tr class="separator:gabaeab5646aeea9844e6d42ca8c73fe3a"><td class="memSeparator" colspan="2"> </td></tr>
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</table>
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<a name="details" id="details"></a><h2 class="groupheader">Description</h2>
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<dl class="section user"><dt></dt><dd>The CMSIS DSP library includes specialized algorithms for computing the FFT of real data sequences. The FFT is defined over complex data but in many applications the input is real. Real FFT algorithms take advantage of the symmetry properties of the FFT and have a speed advantage over complex algorithms of the same length. </dd></dl>
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<dl class="section user"><dt></dt><dd>The Fast RFFT algorithm relays on the mixed radix CFFT that save processor usage. </dd></dl>
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<dl class="section user"><dt></dt><dd>The real length N forward FFT of a sequence is computed using the steps shown below. </dd></dl>
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<dl class="section user"><dt></dt><dd><div class="image">
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<img src="RFFT.gif" alt=""/>
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<div class="caption">
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Real Fast Fourier Transform</div></div>
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</dd></dl>
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<dl class="section user"><dt></dt><dd>The real sequence is initially treated as if it were complex to perform a CFFT. Later, a processing stage reshapes the data to obtain half of the frequency spectrum in complex format.</dd></dl>
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<dl class="section user"><dt></dt><dd>The input for the inverse RFFT should keep the same format as the output of the forward RFFT. A first processing stage pre-process the data to later perform an inverse CFFT. </dd></dl>
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<dl class="section user"><dt></dt><dd><div class="image">
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<img src="RIFFT.gif" alt=""/>
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<div class="caption">
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Real Inverse Fast Fourier Transform</div></div>
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</dd></dl>
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<dl class="section user"><dt></dt><dd>The algorithms for floating-point, Q15, and Q31 data are slightly different and we describe each algorithm in turn. </dd></dl>
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<dl class="section user"><dt>Floating-point</dt><dd>The main functions are <a class="el" href="group__RealFFT.html#ga5d2ec62f3e35575eba467d09ddcd98b5">arm_rfft_fast_f32()</a> and <a class="el" href="group__RealFFT.html#gac5fceb172551e7c11eb4d0e17ef15aa3">arm_rfft_fast_init_f32()</a>. The older functions <a class="el" href="group__RealFFT.html#ga3df1766d230532bc068fc4ed69d0fcdc">arm_rfft_f32()</a> and <a class="el" href="group__RealFFT.html#ga10717ee326bf50832ef1c25b85a23068">arm_rfft_init_f32()</a> have been deprecated but are still documented. For f16, the functions are <a class="el" href="group__RealFFT.html#gaf018157c88626e83de3d9143f5273d18">arm_rfft_fast_f16()</a> and <a class="el" href="group__RealFFT.html#gacc1c721dd5a690a4c90cfb0264058659">arm_rfft_fast_init_f16()</a>. For f64, the functions are <a class="el" href="group__RealFFT.html#gae3b00f039305039732f7364171da89fb">arm_rfft_fast_f64()</a> and <a class="el" href="group__RealFFT.html#ga51ca806ce1aa56a231684add8d2820bb">arm_rfft_fast_init_f64()</a>. </dd></dl>
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<dl class="section user"><dt></dt><dd>The FFT of a real N-point sequence has even symmetry in the frequency domain. The second half of the data equals the conjugate of the first half flipped in frequency. This conjugate part is not computed by the float RFFT. As consequence, the output of a N point real FFT should be a N//2 + 1 complex numbers so N + 2 floats. </dd></dl>
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<dl class="section user"><dt></dt><dd>It happens that the first complex of number of the RFFT output is actually all real. Its real part represents the DC offset. The value at Nyquist frequency is also real.</dd></dl>
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<dl class="section user"><dt></dt><dd>Those two complex numbers can be encoded with 2 floats rather than using two numbers with an imaginary part set to zero. </dd></dl>
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<dl class="section user"><dt></dt><dd>The implementation is using a trick so that the output buffer can be N float : the last real is packaged in the imaginary part of the first complex (since this imaginary part is not used and is zero).</dd></dl>
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<dl class="section user"><dt></dt><dd>The real FFT functions pack the frequency domain data in this fashion. The forward transform outputs the data in this form and the inverse transform expects input data in this form. The function always performs the needed bitreversal so that the input and output data is always in normal order. The functions support lengths of [32, 64, 128, ..., 4096] samples. </dd></dl>
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<dl class="section user"><dt>Q15 and Q31</dt><dd>The real algorithms are defined in a similar manner and utilize N/2 complex transforms behind the scenes.</dd></dl>
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<dl class="section user"><dt></dt><dd>But warning, contrary to the float version, the fixed point implementation RFFT is also computing the conjugate part (except for MVE version) so the output buffer must be bigger. Also the fixed point RFFTs are not using any trick to pack the DC and Nyquist frequency in the same complex number. The RIFFT is not using the conjugate part but it is still using the Nyquist frequency value. The details are given in the documentation for the functions. </dd></dl>
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<dl class="section user"><dt></dt><dd>The complex transforms used internally include scaling to prevent fixed-point overflows. The overall scaling equals 1/(fftLen/2). Due to the use of complex transform internally, the source buffer is modified by the rfft. </dd></dl>
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<dl class="section user"><dt></dt><dd>A separate instance structure must be defined for each transform used but twiddle factor and bit reversal tables can be reused. </dd></dl>
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<dl class="section user"><dt></dt><dd>There is also an associated initialization function for each data type. The initialization function performs the following operations:<ul>
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<li>Sets the values of the internal structure fields.</li>
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<li>Initializes twiddle factor table and bit reversal table pointers.</li>
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<li>Initializes the internal complex FFT data structure. </li>
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</ul>
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</dd></dl>
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<dl class="section user"><dt></dt><dd>Use of the initialization function is optional <b>except for MVE versions where it is mandatory</b>. If you don't use the initialization functions, then the structures should be initialized with code similar to the one below: <pre>
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<a class="el" href="structarm__rfft__instance__q31.html" title="Instance structure for the Q31 RFFT/RIFFT function.">arm_rfft_instance_q31</a> S = {fftLenReal, fftLenBy2, ifftFlagR, bitReverseFlagR, twidCoefRModifier, pTwiddleAReal, pTwiddleBReal, pCfft};
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<a class="el" href="structarm__rfft__instance__q15.html" title="Instance structure for the Q15 RFFT/RIFFT function.">arm_rfft_instance_q15</a> S = {fftLenReal, fftLenBy2, ifftFlagR, bitReverseFlagR, twidCoefRModifier, pTwiddleAReal, pTwiddleBReal, pCfft};
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</pre> where <code>fftLenReal</code> is the length of the real transform; <code>fftLenBy2</code> length of the internal complex transform (fftLenReal/2). <code>ifftFlagR</code> Selects forward (=0) or inverse (=1) transform. <code>bitReverseFlagR</code> Selects bit reversed output (=0) or normal order output (=1). <code>twidCoefRModifier</code> stride modifier for the twiddle factor table. The value is based on the FFT length; <code>pTwiddleAReal</code>points to the A array of twiddle coefficients; <code>pTwiddleBReal</code>points to the B array of twiddle coefficients; <code>pCfft</code> points to the CFFT Instance structure. The CFFT structure must also be initialized. <br />
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</dd></dl>
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<dl class="section user"><dt></dt><dd>Note that with MVE versions you can't initialize instance structures directly and <b>must use the initialization function</b>. </dd></dl>
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<h2 class="groupheader">Function Documentation</h2>
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<a id="ga3df1766d230532bc068fc4ed69d0fcdc" name="ga3df1766d230532bc068fc4ed69d0fcdc"></a>
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<h2 class="memtitle"><span class="permalink"><a href="#ga3df1766d230532bc068fc4ed69d0fcdc">◆ </a></span>arm_rfft_f32()</h2>
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<div class="memitem">
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<td class="memname">void arm_rfft_f32 </td>
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<td>(</td>
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<td class="paramtype">const <a class="el" href="structarm__rfft__instance__f32.html">arm_rfft_instance_f32</a> * </td>
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<td class="paramname"><em>S</em>, </td>
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<tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype"><a class="el" href="arm__math__types_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> * </td>
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<td class="paramname"><em>pSrc</em>, </td>
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</tr>
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<tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype"><a class="el" href="arm__math__types_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> * </td>
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<td class="paramname"><em>pDst</em> </td>
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</tr>
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<tr>
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<td></td>
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<td>)</td>
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<td></td><td></td>
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</tr>
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</table>
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</div><div class="memdoc">
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<dl class="deprecated"><dt><b><a class="el" href="deprecated.html#_deprecated000020">Deprecated:</a></b></dt><dd>Do not use this function. It has been superceded by <a class="el" href="group__RealFFT.html#ga5d2ec62f3e35575eba467d09ddcd98b5">arm_rfft_fast_f32</a> and will be removed in the future. </dd></dl>
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in]</td><td class="paramname">S</td><td>points to an instance of the floating-point RFFT/RIFFT structure </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">pSrc</td><td>points to the input buffer </td></tr>
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<tr><td class="paramdir">[out]</td><td class="paramname">pDst</td><td>points to the output buffer </td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>none </dd></dl>
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</div>
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</div>
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<a id="gaf018157c88626e83de3d9143f5273d18" name="gaf018157c88626e83de3d9143f5273d18"></a>
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<h2 class="memtitle"><span class="permalink"><a href="#gaf018157c88626e83de3d9143f5273d18">◆ </a></span>arm_rfft_fast_f16()</h2>
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<div class="memitem">
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<td class="memname">void arm_rfft_fast_f16 </td>
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<td>(</td>
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<td class="paramtype">const <a class="el" href="structarm__rfft__fast__instance__f16.html">arm_rfft_fast_instance_f16</a> * </td>
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<td class="paramname"><em>S</em>, </td>
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</tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">float16_t * </td>
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<td class="paramname"><em>p</em>, </td>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">float16_t * </td>
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<td class="paramname"><em>pOut</em>, </td>
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</tr>
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<tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint8_t </td>
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<td class="paramname"><em>ifftFlag</em> </td>
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</tr>
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<tr>
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<td></td>
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<td>)</td>
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<td></td><td></td>
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</tr>
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</table>
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</div><div class="memdoc">
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in]</td><td class="paramname">S</td><td>points to an <a class="el" href="structarm__rfft__fast__instance__f16.html" title="Instance structure for the floating-point RFFT/RIFFT function.">arm_rfft_fast_instance_f16</a> structure </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">p</td><td>points to input buffer (Source buffer is modified by this function.) </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">pOut</td><td>points to output buffer </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">ifftFlag</td><td><ul>
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<li>value = 0: RFFT</li>
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<li>value = 1: RIFFT </li>
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</ul>
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</td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>none </dd></dl>
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</div>
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</div>
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<a id="ga5d2ec62f3e35575eba467d09ddcd98b5" name="ga5d2ec62f3e35575eba467d09ddcd98b5"></a>
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<h2 class="memtitle"><span class="permalink"><a href="#ga5d2ec62f3e35575eba467d09ddcd98b5">◆ </a></span>arm_rfft_fast_f32()</h2>
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<td class="memname">void arm_rfft_fast_f32 </td>
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<td>(</td>
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<td class="paramtype">const <a class="el" href="structarm__rfft__fast__instance__f32.html">arm_rfft_fast_instance_f32</a> * </td>
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<td class="paramname"><em>S</em>, </td>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype"><a class="el" href="arm__math__types_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> * </td>
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<td class="paramname"><em>p</em>, </td>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype"><a class="el" href="arm__math__types_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> * </td>
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<td class="paramname"><em>pOut</em>, </td>
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</tr>
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<tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint8_t </td>
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<td class="paramname"><em>ifftFlag</em> </td>
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</tr>
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<tr>
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<td></td>
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<td>)</td>
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</table>
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</div><div class="memdoc">
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in]</td><td class="paramname">S</td><td>points to an <a class="el" href="structarm__rfft__fast__instance__f32.html" title="Instance structure for the floating-point RFFT/RIFFT function.">arm_rfft_fast_instance_f32</a> structure </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">p</td><td>points to input buffer (Source buffer is modified by this function.) </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">pOut</td><td>points to output buffer </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">ifftFlag</td><td><ul>
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<li>value = 0: RFFT</li>
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<li>value = 1: RIFFT </li>
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</ul>
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</td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>none </dd></dl>
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</div>
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</div>
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<a id="gae3b00f039305039732f7364171da89fb" name="gae3b00f039305039732f7364171da89fb"></a>
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<h2 class="memtitle"><span class="permalink"><a href="#gae3b00f039305039732f7364171da89fb">◆ </a></span>arm_rfft_fast_f64()</h2>
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<td class="memname">void arm_rfft_fast_f64 </td>
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<td>(</td>
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<td class="paramtype"><a class="el" href="structarm__rfft__fast__instance__f64.html">arm_rfft_fast_instance_f64</a> * </td>
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<td class="paramname"><em>S</em>, </td>
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<tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype"><a class="el" href="arm__math__types_8h.html#ac55f3ae81b5bc9053760baacf57e47f4">float64_t</a> * </td>
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<td class="paramname"><em>p</em>, </td>
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</tr>
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<tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype"><a class="el" href="arm__math__types_8h.html#ac55f3ae81b5bc9053760baacf57e47f4">float64_t</a> * </td>
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<td class="paramname"><em>pOut</em>, </td>
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</tr>
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<tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint8_t </td>
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<td class="paramname"><em>ifftFlag</em> </td>
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</tr>
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<tr>
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<td></td>
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<td>)</td>
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<td></td><td></td>
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</table>
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</div><div class="memdoc">
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in]</td><td class="paramname">S</td><td>points to an <a class="el" href="structarm__rfft__fast__instance__f64.html" title="Instance structure for the Double Precision Floating-point RFFT/RIFFT function.">arm_rfft_fast_instance_f64</a> structure </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">p</td><td>points to input buffer (Source buffer is modified by this function.) </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">pOut</td><td>points to output buffer </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">ifftFlag</td><td><ul>
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<li>value = 0: RFFT</li>
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<li>value = 1: RIFFT </li>
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</ul>
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</td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>none </dd></dl>
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</div>
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</div>
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<a id="gacc1c721dd5a690a4c90cfb0264058659" name="gacc1c721dd5a690a4c90cfb0264058659"></a>
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<h2 class="memtitle"><span class="permalink"><a href="#gacc1c721dd5a690a4c90cfb0264058659">◆ </a></span>arm_rfft_fast_init_f16()</h2>
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<td class="memname"><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> arm_rfft_fast_init_f16 </td>
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<td>(</td>
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<td class="paramtype"><a class="el" href="structarm__rfft__fast__instance__f16.html">arm_rfft_fast_instance_f16</a> * </td>
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<td class="paramname"><em>S</em>, </td>
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</tr>
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<tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint16_t </td>
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<td class="paramname"><em>fftLen</em> </td>
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</tr>
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<tr>
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<td></td>
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<td>)</td>
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<td></td><td></td>
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</div><div class="memdoc">
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in,out]</td><td class="paramname">S</td><td>points to an <a class="el" href="structarm__rfft__fast__instance__f16.html" title="Instance structure for the floating-point RFFT/RIFFT function.">arm_rfft_fast_instance_f16</a> structure </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">fftLen</td><td>length of the Real Sequence </td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>execution status<ul>
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<li><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a9f8b2a10bd827fb4600e77d455902eb0">ARM_MATH_SUCCESS</a> : Operation successful</li>
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<li><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a74897e18d4b8f62b12a7d8a01dd2bb35">ARM_MATH_ARGUMENT_ERROR</a> : <code>fftLen</code> is not a supported length</li>
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</ul>
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</dd></dl>
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<dl class="section user"><dt>Description</dt><dd>The parameter <code>fftLen</code> specifies the length of RFFT/CIFFT process. Supported FFT Lengths are 32, 64, 128, 256, 512, 1024, 2048, 4096. </dd></dl>
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<dl class="section user"><dt></dt><dd>This Function also initializes Twiddle factor table pointer and Bit reversal table pointer. </dd></dl>
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</div>
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</div>
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<a id="gac5fceb172551e7c11eb4d0e17ef15aa3" name="gac5fceb172551e7c11eb4d0e17ef15aa3"></a>
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<h2 class="memtitle"><span class="permalink"><a href="#gac5fceb172551e7c11eb4d0e17ef15aa3">◆ </a></span>arm_rfft_fast_init_f32()</h2>
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<td class="memname"><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> arm_rfft_fast_init_f32 </td>
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<td>(</td>
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<td class="paramtype"><a class="el" href="structarm__rfft__fast__instance__f32.html">arm_rfft_fast_instance_f32</a> * </td>
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<td class="paramname"><em>S</em>, </td>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint16_t </td>
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<td class="paramname"><em>fftLen</em> </td>
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<td></td>
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<td>)</td>
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<td></td><td></td>
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</div><div class="memdoc">
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in,out]</td><td class="paramname">S</td><td>points to an <a class="el" href="structarm__rfft__fast__instance__f32.html" title="Instance structure for the floating-point RFFT/RIFFT function.">arm_rfft_fast_instance_f32</a> structure </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">fftLen</td><td>length of the Real Sequence </td></tr>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>execution status<ul>
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<li><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a9f8b2a10bd827fb4600e77d455902eb0">ARM_MATH_SUCCESS</a> : Operation successful</li>
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<li><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a74897e18d4b8f62b12a7d8a01dd2bb35">ARM_MATH_ARGUMENT_ERROR</a> : <code>fftLen</code> is not a supported length</li>
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</ul>
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</dd></dl>
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<dl class="section user"><dt>Description</dt><dd>The parameter <code>fftLen</code> specifies the length of RFFT/CIFFT process. Supported FFT Lengths are 32, 64, 128, 256, 512, 1024, 2048, 4096. </dd></dl>
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<dl class="section user"><dt></dt><dd>This Function also initializes Twiddle factor table pointer and Bit reversal table pointer. </dd></dl>
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<a id="ga51ca806ce1aa56a231684add8d2820bb" name="ga51ca806ce1aa56a231684add8d2820bb"></a>
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<h2 class="memtitle"><span class="permalink"><a href="#ga51ca806ce1aa56a231684add8d2820bb">◆ </a></span>arm_rfft_fast_init_f64()</h2>
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<td class="memname"><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> arm_rfft_fast_init_f64 </td>
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<td>(</td>
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<td class="paramtype"><a class="el" href="structarm__rfft__fast__instance__f64.html">arm_rfft_fast_instance_f64</a> * </td>
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<td class="paramname"><em>S</em>, </td>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint16_t </td>
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<td class="paramname"><em>fftLen</em> </td>
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</tr>
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<tr>
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<td></td>
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<td>)</td>
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<td></td><td></td>
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</tr>
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</table>
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</div><div class="memdoc">
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in,out]</td><td class="paramname">S</td><td>points to an <a class="el" href="structarm__rfft__fast__instance__f64.html" title="Instance structure for the Double Precision Floating-point RFFT/RIFFT function.">arm_rfft_fast_instance_f64</a> structure </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">fftLen</td><td>length of the Real Sequence </td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>execution status<ul>
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<li><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a9f8b2a10bd827fb4600e77d455902eb0">ARM_MATH_SUCCESS</a> : Operation successful</li>
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<li><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a74897e18d4b8f62b12a7d8a01dd2bb35">ARM_MATH_ARGUMENT_ERROR</a> : <code>fftLen</code> is not a supported length</li>
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</ul>
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</dd></dl>
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<dl class="section user"><dt>Description</dt><dd>The parameter <code>fftLen</code> specifies the length of RFFT/CIFFT process. Supported FFT Lengths are 32, 64, 128, 256, 512, 1024, 2048, 4096. </dd></dl>
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<dl class="section user"><dt></dt><dd>This Function also initializes Twiddle factor table pointer and Bit reversal table pointer. </dd></dl>
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</div>
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<a id="ga10717ee326bf50832ef1c25b85a23068" name="ga10717ee326bf50832ef1c25b85a23068"></a>
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<h2 class="memtitle"><span class="permalink"><a href="#ga10717ee326bf50832ef1c25b85a23068">◆ </a></span>arm_rfft_init_f32()</h2>
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<td class="memname"><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> arm_rfft_init_f32 </td>
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<td>(</td>
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<td class="paramtype"><a class="el" href="structarm__rfft__instance__f32.html">arm_rfft_instance_f32</a> * </td>
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<td class="paramname"><em>S</em>, </td>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype"><a class="el" href="structarm__cfft__radix4__instance__f32.html">arm_cfft_radix4_instance_f32</a> * </td>
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<td class="paramname"><em>S_CFFT</em>, </td>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint32_t </td>
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<td class="paramname"><em>fftLenReal</em>, </td>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint32_t </td>
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<td class="paramname"><em>ifftFlagR</em>, </td>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint32_t </td>
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<td class="paramname"><em>bitReverseFlag</em> </td>
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</tr>
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<tr>
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<td></td>
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<td>)</td>
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</div><div class="memdoc">
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<dl class="deprecated"><dt><b><a class="el" href="deprecated.html#_deprecated000021">Deprecated:</a></b></dt><dd>Do not use this function. It has been superceded by <a class="el" href="group__RealFFT.html#gac5fceb172551e7c11eb4d0e17ef15aa3">arm_rfft_fast_init_f32</a> and will be removed in the future. </dd></dl>
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in,out]</td><td class="paramname">S</td><td>points to an instance of the floating-point RFFT/RIFFT structure </td></tr>
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<tr><td class="paramdir">[in,out]</td><td class="paramname">S_CFFT</td><td>points to an instance of the floating-point CFFT/CIFFT structure </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">fftLenReal</td><td>length of the FFT. </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">ifftFlagR</td><td>flag that selects transform direction<ul>
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<li>value = 0: forward transform</li>
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<li>value = 1: inverse transform </li>
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</ul>
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</td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">bitReverseFlag</td><td>flag that enables / disables bit reversal of output<ul>
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<li>value = 0: disables bit reversal of output</li>
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<li>value = 1: enables bit reversal of output </li>
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</ul>
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</td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>execution status<ul>
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<li><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a9f8b2a10bd827fb4600e77d455902eb0">ARM_MATH_SUCCESS</a> : Operation successful</li>
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<li><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a74897e18d4b8f62b12a7d8a01dd2bb35">ARM_MATH_ARGUMENT_ERROR</a> : <code>fftLenReal</code> is not a supported length</li>
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</ul>
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</dd></dl>
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<dl class="section user"><dt>Description</dt><dd>The parameter <code>fftLenReal</code>specifies length of RFFT/RIFFT Process. Supported FFT Lengths are 128, 512, 2048. </dd></dl>
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<dl class="section user"><dt></dt><dd>The parameter <code>ifftFlagR</code> controls whether a forward or inverse transform is computed. Set(=1) ifftFlagR to calculate RIFFT, otherwise RFFT is calculated. </dd></dl>
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<dl class="section user"><dt></dt><dd>The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order. Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order. </dd></dl>
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<dl class="section user"><dt></dt><dd>This function also initializes Twiddle factor table. </dd></dl>
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</div>
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<a id="ga053450cc600a55410ba5b5605e96245d" name="ga053450cc600a55410ba5b5605e96245d"></a>
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<h2 class="memtitle"><span class="permalink"><a href="#ga053450cc600a55410ba5b5605e96245d">◆ </a></span>arm_rfft_init_q15()</h2>
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<td class="memname"><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> arm_rfft_init_q15 </td>
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<td>(</td>
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<td class="paramtype"><a class="el" href="structarm__rfft__instance__q15.html">arm_rfft_instance_q15</a> * </td>
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<td class="paramname"><em>S</em>, </td>
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</tr>
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<tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint32_t </td>
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<td class="paramname"><em>fftLenReal</em>, </td>
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</tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint32_t </td>
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<td class="paramname"><em>ifftFlagR</em>, </td>
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</tr>
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<tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint32_t </td>
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<td class="paramname"><em>bitReverseFlag</em> </td>
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</tr>
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<tr>
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<td></td>
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<td>)</td>
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<td></td><td></td>
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</tr>
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</table>
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</div><div class="memdoc">
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in,out]</td><td class="paramname">S</td><td>points to an instance of the Q15 RFFT/RIFFT structure </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">fftLenReal</td><td>length of the FFT </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">ifftFlagR</td><td>flag that selects transform direction<ul>
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<li>value = 0: forward transform</li>
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<li>value = 1: inverse transform </li>
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</ul>
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</td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">bitReverseFlag</td><td>flag that enables / disables bit reversal of output<ul>
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<li>value = 0: disables bit reversal of output</li>
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<li>value = 1: enables bit reversal of output </li>
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</ul>
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</td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>execution status<ul>
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<li><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a9f8b2a10bd827fb4600e77d455902eb0">ARM_MATH_SUCCESS</a> : Operation successful</li>
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<li><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a74897e18d4b8f62b12a7d8a01dd2bb35">ARM_MATH_ARGUMENT_ERROR</a> : <code>fftLenReal</code> is not a supported length</li>
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</ul>
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</dd></dl>
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<dl class="section user"><dt>Details</dt><dd>The parameter <code>fftLenReal</code> specifies length of RFFT/RIFFT Process. Supported FFT Lengths are 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192. </dd></dl>
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<dl class="section user"><dt></dt><dd>The parameter <code>ifftFlagR</code> controls whether a forward or inverse transform is computed. Set(=1) ifftFlagR to calculate RIFFT, otherwise RFFT is calculated. </dd></dl>
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<dl class="section user"><dt></dt><dd>The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order. Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order. </dd></dl>
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<dl class="section user"><dt></dt><dd>This function also initializes Twiddle factor table. </dd></dl>
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</div>
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<a id="ga5abde938abbe72e95c5bab080eb33c45" name="ga5abde938abbe72e95c5bab080eb33c45"></a>
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<h2 class="memtitle"><span class="permalink"><a href="#ga5abde938abbe72e95c5bab080eb33c45">◆ </a></span>arm_rfft_init_q31()</h2>
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<td class="memname"><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> arm_rfft_init_q31 </td>
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<td>(</td>
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<td class="paramtype"><a class="el" href="structarm__rfft__instance__q31.html">arm_rfft_instance_q31</a> * </td>
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<td class="paramname"><em>S</em>, </td>
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</tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint32_t </td>
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<td class="paramname"><em>fftLenReal</em>, </td>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint32_t </td>
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<td class="paramname"><em>ifftFlagR</em>, </td>
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</tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint32_t </td>
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<td class="paramname"><em>bitReverseFlag</em> </td>
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</tr>
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<tr>
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<td></td>
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<td>)</td>
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<td></td><td></td>
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</tr>
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</table>
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</div><div class="memdoc">
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in,out]</td><td class="paramname">S</td><td>points to an instance of the Q31 RFFT/RIFFT structure </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">fftLenReal</td><td>length of the FFT </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">ifftFlagR</td><td>flag that selects transform direction<ul>
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<li>value = 0: forward transform</li>
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<li>value = 1: inverse transform </li>
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</ul>
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</td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">bitReverseFlag</td><td>flag that enables / disables bit reversal of output<ul>
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<li>value = 0: disables bit reversal of output</li>
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<li>value = 1: enables bit reversal of output </li>
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</ul>
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</td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>execution status<ul>
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<li><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a9f8b2a10bd827fb4600e77d455902eb0">ARM_MATH_SUCCESS</a> : Operation successful</li>
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<li><a class="el" href="arm__math__types_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a74897e18d4b8f62b12a7d8a01dd2bb35">ARM_MATH_ARGUMENT_ERROR</a> : <code>fftLenReal</code> is not a supported length</li>
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</ul>
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</dd></dl>
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<dl class="section user"><dt>Details</dt><dd>The parameter <code>fftLenReal</code> specifies length of RFFT/RIFFT Process. Supported FFT Lengths are 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192. </dd></dl>
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<dl class="section user"><dt></dt><dd>The parameter <code>ifftFlagR</code> controls whether a forward or inverse transform is computed. Set(=1) ifftFlagR to calculate RIFFT, otherwise RFFT is calculated. </dd></dl>
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<dl class="section user"><dt></dt><dd>The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order. Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order. </dd></dl>
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<dl class="section user"><dt></dt><dd>This function also initializes Twiddle factor table. </dd></dl>
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</div>
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</div>
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<a id="ga00e615f5db21736ad5b27fb6146f3fc5" name="ga00e615f5db21736ad5b27fb6146f3fc5"></a>
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<h2 class="memtitle"><span class="permalink"><a href="#ga00e615f5db21736ad5b27fb6146f3fc5">◆ </a></span>arm_rfft_q15()</h2>
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<td class="memname">void arm_rfft_q15 </td>
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<td>(</td>
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<td class="paramtype">const <a class="el" href="structarm__rfft__instance__q15.html">arm_rfft_instance_q15</a> * </td>
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<td class="paramname"><em>S</em>, </td>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype"><a class="el" href="arm__math__types_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> * </td>
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<td class="paramname"><em>pSrc</em>, </td>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype"><a class="el" href="arm__math__types_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> * </td>
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<td class="paramname"><em>pDst</em> </td>
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</tr>
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<tr>
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<td></td>
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<td>)</td>
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<td></td><td></td>
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</tr>
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</table>
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</div><div class="memdoc">
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in]</td><td class="paramname">S</td><td>points to an instance of the Q15 RFFT/RIFFT structure </td></tr>
|
|
<tr><td class="paramdir">[in]</td><td class="paramname">pSrc</td><td>points to input buffer (Source buffer is modified by this function.) </td></tr>
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<tr><td class="paramdir">[out]</td><td class="paramname">pDst</td><td>points to output buffer </td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>none</dd></dl>
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<dl class="section user"><dt>Input an output formats</dt><dd>Internally input is downscaled by 2 for every stage to avoid saturations inside CFFT/CIFFT process. Hence the output format is different for different RFFT sizes. The input and output formats for different RFFT sizes and number of bits to upscale are mentioned in the tables below for RFFT and RIFFT: </dd></dl>
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<dl class="section user"><dt>Input and Output formats for RFFT Q15</dt><dd></dd></dl>
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<table class="markdownTable">
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<tr class="markdownTableHead">
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<th class="markdownTableHeadRight">RFFT Size </th><th class="markdownTableHeadRight">Input Format </th><th class="markdownTableHeadRight">Output Format </th><th class="markdownTableHeadRight">Number of bits to upscale </th></tr>
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<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">32 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">6.10 </td><td class="markdownTableBodyRight">5 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">64 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">7.9 </td><td class="markdownTableBodyRight">6 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">128 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">8.8 </td><td class="markdownTableBodyRight">7 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">256 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">9.7 </td><td class="markdownTableBodyRight">8 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">512 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">10.6 </td><td class="markdownTableBodyRight">9 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">1024 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">11.5 </td><td class="markdownTableBodyRight">10 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">2048 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">12.4 </td><td class="markdownTableBodyRight">11 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">4096 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">13.3 </td><td class="markdownTableBodyRight">12 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">8192 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">14.2 </td><td class="markdownTableBodyRight">13 </td></tr>
|
|
</table>
|
|
<dl class="section user"><dt>Input and Output formats for RIFFT Q15</dt><dd></dd></dl>
|
|
<table class="markdownTable">
|
|
<tr class="markdownTableHead">
|
|
<th class="markdownTableHeadRight">RIFFT Size </th><th class="markdownTableHeadRight">Input Format </th><th class="markdownTableHeadRight">Output Format </th><th class="markdownTableHeadRight">Number of bits to upscale </th></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">32 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">6.10 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">64 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">7.9 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">128 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">8.8 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">256 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">9.7 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">512 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">10.6 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">1024 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">11.5 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">2048 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">12.4 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">4096 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">13.3 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">8192 </td><td class="markdownTableBodyRight">1.15 </td><td class="markdownTableBodyRight">14.2 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
</table>
|
|
<dl class="section user"><dt></dt><dd>If the input buffer is of length N (fftLenReal), the output buffer must have length 2N since it is containing the conjugate part (except for MVE version where N+2 is enough). The input buffer is modified by this function. </dd></dl>
|
|
<dl class="section user"><dt></dt><dd>For the RIFFT, the source buffer must have length N+2 since the Nyquist frequency value is needed but conjugate part is ignored. It is not using the packing trick of the float version. </dd></dl>
|
|
|
|
</div>
|
|
</div>
|
|
<a id="gabaeab5646aeea9844e6d42ca8c73fe3a" name="gabaeab5646aeea9844e6d42ca8c73fe3a"></a>
|
|
<h2 class="memtitle"><span class="permalink"><a href="#gabaeab5646aeea9844e6d42ca8c73fe3a">◆ </a></span>arm_rfft_q31()</h2>
|
|
|
|
<div class="memitem">
|
|
<div class="memproto">
|
|
<table class="memname">
|
|
<tr>
|
|
<td class="memname">void arm_rfft_q31 </td>
|
|
<td>(</td>
|
|
<td class="paramtype">const <a class="el" href="structarm__rfft__instance__q31.html">arm_rfft_instance_q31</a> * </td>
|
|
<td class="paramname"><em>S</em>, </td>
|
|
</tr>
|
|
<tr>
|
|
<td class="paramkey"></td>
|
|
<td></td>
|
|
<td class="paramtype"><a class="el" href="arm__math__types_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> * </td>
|
|
<td class="paramname"><em>pSrc</em>, </td>
|
|
</tr>
|
|
<tr>
|
|
<td class="paramkey"></td>
|
|
<td></td>
|
|
<td class="paramtype"><a class="el" href="arm__math__types_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> * </td>
|
|
<td class="paramname"><em>pDst</em> </td>
|
|
</tr>
|
|
<tr>
|
|
<td></td>
|
|
<td>)</td>
|
|
<td></td><td></td>
|
|
</tr>
|
|
</table>
|
|
</div><div class="memdoc">
|
|
<dl class="params"><dt>Parameters</dt><dd>
|
|
<table class="params">
|
|
<tr><td class="paramdir">[in]</td><td class="paramname">S</td><td>points to an instance of the Q31 RFFT/RIFFT structure </td></tr>
|
|
<tr><td class="paramdir">[in]</td><td class="paramname">pSrc</td><td>points to input buffer (Source buffer is modified by this function) </td></tr>
|
|
<tr><td class="paramdir">[out]</td><td class="paramname">pDst</td><td>points to output buffer </td></tr>
|
|
</table>
|
|
</dd>
|
|
</dl>
|
|
<dl class="section return"><dt>Returns</dt><dd>none</dd></dl>
|
|
<dl class="section user"><dt>Input an output formats</dt><dd>Internally input is downscaled by 2 for every stage to avoid saturations inside CFFT/CIFFT process. Hence the output format is different for different RFFT sizes. The input and output formats for different RFFT sizes and number of bits to upscale are mentioned in the tables below for RFFT and RIFFT: </dd></dl>
|
|
<dl class="section user"><dt>Input and Output formats for RFFT Q31</dt><dd></dd></dl>
|
|
<table class="markdownTable">
|
|
<tr class="markdownTableHead">
|
|
<th class="markdownTableHeadRight">RFFT Size </th><th class="markdownTableHeadRight">Input Format </th><th class="markdownTableHeadRight">Output Format </th><th class="markdownTableHeadRight">Number of bits to upscale </th></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">32 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">6.26 </td><td class="markdownTableBodyRight">5 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">64 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">7.25 </td><td class="markdownTableBodyRight">6 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">128 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">8.24 </td><td class="markdownTableBodyRight">7 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">256 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">9.23 </td><td class="markdownTableBodyRight">8 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">512 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">10.22 </td><td class="markdownTableBodyRight">9 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">1024 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">11.21 </td><td class="markdownTableBodyRight">10 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">2048 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">12.20 </td><td class="markdownTableBodyRight">11 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">4096 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">13.19 </td><td class="markdownTableBodyRight">12 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">8192 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">14.18 </td><td class="markdownTableBodyRight">13 </td></tr>
|
|
</table>
|
|
<dl class="section user"><dt>Input and Output formats for RIFFT Q31</dt><dd></dd></dl>
|
|
<table class="markdownTable">
|
|
<tr class="markdownTableHead">
|
|
<th class="markdownTableHeadRight">RIFFT Size </th><th class="markdownTableHeadRight">Input Format </th><th class="markdownTableHeadRight">Output Format </th><th class="markdownTableHeadRight">Number of bits to upscale </th></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">32 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">6.26 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">64 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">7.25 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">128 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">8.24 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">256 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">9.23 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">512 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">10.22 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">1024 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">11.21 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">2048 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">12.20 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowEven">
|
|
<td class="markdownTableBodyRight">4096 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">13.19 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
<tr class="markdownTableRowOdd">
|
|
<td class="markdownTableBodyRight">8192 </td><td class="markdownTableBodyRight">1.31 </td><td class="markdownTableBodyRight">14.18 </td><td class="markdownTableBodyRight">0 </td></tr>
|
|
</table>
|
|
<dl class="section user"><dt></dt><dd>If the input buffer is of length N (fftLenReal), the output buffer must have length 2N since it is containing the conjugate part (except for MVE version where N+2 is enough). The input buffer is modified by this function. </dd></dl>
|
|
<dl class="section user"><dt></dt><dd>For the RIFFT, the source buffer must have length N+2 since the Nyquist frequency value is needed but conjugate part is ignored. It is not using the packing trick of the float version. </dd></dl>
|
|
|
|
</div>
|
|
</div>
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