/* * Copyright (c) 2008-2020 Stefan Krah. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include "mpdecimal.h" #include <assert.h> #include "bits.h" #include "constants.h" #include "difradix2.h" #include "numbertheory.h" #include "umodarith.h" /* Bignum: The actual transform routine (decimation in frequency). */ /* * Generate index pairs (x, bitreverse(x)) and carry out the permutation. * n must be a power of two. * Algorithm due to Brent/Lehmann, see Joerg Arndt, "Matters Computational", * Chapter 1.14.4. [http://www.jjj.de/fxt/] */ static inline void bitreverse_permute(mpd_uint_t a[], mpd_size_t n) { … } /* Fast Number Theoretic Transform, decimation in frequency. */ void fnt_dif2(mpd_uint_t a[], mpd_size_t n, struct fnt_params *tparams) { … }
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