75 lines
2.4 KiB
C
75 lines
2.4 KiB
C
/*
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Copyright 2009, 2011 William Hart. All rights reserved.
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Redistribution and use in source and binary forms, with or without modification, are
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permitted provided that the following conditions are met:
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1. Redistributions of source code must retain the above copyright notice, this list of
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conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright notice, this list
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of conditions and the following disclaimer in the documentation and/or other materials
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provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY William Hart ``AS IS'' AND ANY EXPRESS OR IMPLIED
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WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL William Hart OR
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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The views and conclusions contained in the software and documentation are those of the
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authors and should not be interpreted as representing official policies, either expressed
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or implied, of William Hart.
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*/
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#include "mpir.h"
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#include "gmp-impl.h"
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void fft_butterfly(mp_ptr s, mp_ptr t, mp_ptr i1,
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mp_ptr i2, mp_size_t i, mp_size_t limbs, mp_bitcnt_t w)
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{
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mp_size_t y;
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mp_bitcnt_t b1;
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b1 = i*w;
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y = b1/GMP_LIMB_BITS;
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b1 = b1%GMP_LIMB_BITS;
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butterfly_lshB(s, t, i1, i2, limbs, 0, y);
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mpn_mul_2expmod_2expp1(t, t, limbs, b1);
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}
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void fft_radix2(mp_ptr * ii,
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mp_size_t n, mp_bitcnt_t w, mp_ptr * t1, mp_ptr * t2)
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{
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mp_size_t i;
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mp_size_t limbs = (w*n)/GMP_LIMB_BITS;
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if (n == 1)
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{
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fft_butterfly(*t1, *t2, ii[0], ii[1], 0, limbs, w);
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MP_PTR_SWAP(ii[0], *t1);
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MP_PTR_SWAP(ii[1], *t2);
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return;
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}
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for (i = 0; i < n; i++)
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{
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fft_butterfly(*t1, *t2, ii[i], ii[n+i], i, limbs, w);
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MP_PTR_SWAP(ii[i], *t1);
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MP_PTR_SWAP(ii[n+i], *t2);
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}
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fft_radix2(ii, n/2, 2*w, t1, t2);
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fft_radix2(ii + n, n/2, 2*w, t1, t2);
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}
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