106 lines
4.4 KiB
C
106 lines
4.4 KiB
C
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/*
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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 "gmp.h"
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#include "flint.h"
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#include "fft.h"
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void butterfly_rshB(mp_limb_t * t, mp_limb_t * u, mp_limb_t * i1,
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mp_limb_t * i2, mp_size_t limbs, mp_size_t x, mp_size_t y)
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{
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mp_limb_t cy, cy1, cy2, cy3;
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if (x == 0)
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{
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if (y == 0)
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{
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cy = fft_sumdiff(t, u, i1, i2, limbs + 1);
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} else /* y != 0 */
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{
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cy = fft_sumdiff(t, u, i1, i2 + y, limbs - y);
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cy1 = (cy>>1);
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cy2 = -(cy&1);
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cy = fft_sumdiff(u + limbs - y, t + limbs - y, i1 + limbs - y, i2, y);
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u[limbs] = (cy>>1) + i1[limbs];
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t[limbs] = i1[limbs] - (cy&1);
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mpn_addmod_2expp1_1(t + limbs - y, y, cy1 + i2[limbs]);
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mpn_addmod_2expp1_1(u + limbs - y, y, cy2 - i2[limbs]);
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}
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} else if (y == 0) /* x != 0 */
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{
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cy = fft_sumdiff(t, u, i1 + x, i2, limbs - x);
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cy1 = (cy>>1);
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cy2 = -(cy&1);
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cy3 = mpn_neg_n(i1, i1, x);
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cy = fft_sumdiff(t + limbs - x, u + limbs - x, i1, i2 + limbs - x, x);
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u[limbs] = -cy3 - (cy&1) - i2[limbs];
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t[limbs] = -cy3 + i2[limbs] + (cy>>1);
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mpn_addmod_2expp1_1(t + limbs - x, x, cy1 + i1[limbs]);
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mpn_addmod_2expp1_1(u + limbs - x, x, cy2 + i1[limbs]);
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} else if (x == y)
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{
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cy = fft_sumdiff(t, u, i1 + x, i2 + x, limbs - x);
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cy1 = (cy>>1);
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cy2 = -(cy&1);
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cy = fft_sumdiff(t + limbs - x, u + limbs - x, i2, i1, x);
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cy3 = mpn_neg_n(t + limbs - x, t + limbs - x, x);
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u[limbs] = -(cy&1);
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t[limbs] = -(cy>>1) - cy3;
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mpn_addmod_2expp1_1(t + limbs - x, x, cy1 + i1[limbs] + i2[limbs]);
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mpn_addmod_2expp1_1(u + limbs - x, x, cy2 + i1[limbs] - i2[limbs]);
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} else if (x > y)
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{
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cy = fft_sumdiff(t + limbs - y, u + limbs - y, i2, i1 + x - y, y);
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cy3 = mpn_neg_n(t + limbs - y, t + limbs - y, y);
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t[limbs] = -(cy>>1) - cy3;
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u[limbs] = -(cy&1);
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cy3 = mpn_neg_n(i1, i1, x - y);
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cy = fft_sumdiff(t + limbs - x, u + limbs - x, i1, i2 + limbs - x + y, x - y);
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mpn_addmod_2expp1_1(t + limbs - y, y, (cy>>1) + i2[limbs] - cy3);
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mpn_addmod_2expp1_1(u + limbs - y, y, -(cy&1) - i2[limbs] - cy3);
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cy = fft_sumdiff(t, u, i1 + x, i2 + y, limbs - x);
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mpn_addmod_2expp1_1(t + limbs - x, x, (cy>>1) + i1[limbs]);
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mpn_addmod_2expp1_1(u + limbs - x, x, -(cy&1) + i1[limbs]);
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} else /* x < y */
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{
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cy = fft_sumdiff(t + limbs - x, u + limbs - x, i2 + y - x, i1, x);
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cy3 = mpn_neg_n(t + limbs - x, t + limbs - x, x);
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t[limbs] = -(cy>>1) - cy3;
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u[limbs] = -(cy&1);
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cy3 = mpn_neg_n(i2, i2, y - x);
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cy = fft_sumdiff(t + limbs - y, u + limbs - y, i1 + limbs - y + x, i2, y - x);
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mpn_addmod_2expp1_1(t + limbs - x, x, (cy>>1) + i1[limbs] - cy3);
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mpn_addmod_2expp1_1(u + limbs - x, x, -(cy&1) + i1[limbs] + cy3);
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cy = fft_sumdiff(t, u, i1 + x, i2 + y, limbs - y);
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mpn_addmod_2expp1_1(t + limbs - y, y, (cy>>1) + i2[limbs]);
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mpn_addmod_2expp1_1(u + limbs - y, y, -(cy&1) - i2[limbs]);
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}
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}
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