111 lines
3.7 KiB
C
111 lines
3.7 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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mp_size_t
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mpir_fft_split_limbs(mp_ptr * poly, mp_srcptr limbs,
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mp_size_t total_limbs, mp_size_t coeff_limbs, mp_size_t output_limbs)
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{
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mp_size_t i, skip, length = (total_limbs - 1)/coeff_limbs + 1;
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for (skip = 0, i = 0; skip + coeff_limbs <= total_limbs; skip += coeff_limbs, i++)
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{
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mpn_zero(poly[i], output_limbs + 1);
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mpn_copyi(poly[i], limbs + skip, coeff_limbs);
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}
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if (i < length)
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mpn_zero(poly[i], output_limbs + 1);
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if (total_limbs > skip)
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mpn_copyi(poly[i], limbs + skip, total_limbs - skip);
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return length;
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}
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mp_size_t mpir_fft_split_bits(mp_ptr * poly, mp_srcptr limbs,
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mp_size_t total_limbs, mp_bitcnt_t bits, mp_size_t output_limbs)
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{
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mp_size_t i, coeff_limbs, limbs_left, length = (GMP_LIMB_BITS*total_limbs - 1)/bits + 1;
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mp_bitcnt_t shift_bits, top_bits = ((GMP_LIMB_BITS - 1) & bits);
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mp_srcptr limb_ptr;
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mp_limb_t mask;
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if (top_bits == 0)
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return mpir_fft_split_limbs(poly, limbs, total_limbs, bits/GMP_LIMB_BITS, output_limbs);
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coeff_limbs = (bits/GMP_LIMB_BITS) + 1;
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mask = (((mp_limb_t)1)<<top_bits) - 1;
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shift_bits = 0L;
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limb_ptr = limbs;
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for (i = 0; i < length - 1; i++)
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{
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mpn_zero(poly[i], output_limbs + 1);
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if (!shift_bits)
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{
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mpn_copyi(poly[i], limb_ptr, coeff_limbs);
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poly[i][coeff_limbs - 1] &= mask;
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limb_ptr += (coeff_limbs - 1);
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shift_bits += top_bits;
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} else
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{
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mpn_rshift(poly[i], limb_ptr, coeff_limbs, shift_bits);
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limb_ptr += (coeff_limbs - 1);
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shift_bits += top_bits;
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if (shift_bits >= GMP_LIMB_BITS)
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{
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limb_ptr++;
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poly[i][coeff_limbs - 1] += (limb_ptr[0] << (GMP_LIMB_BITS - (shift_bits - top_bits)));
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shift_bits -= GMP_LIMB_BITS;
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}
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poly[i][coeff_limbs - 1] &= mask;
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}
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}
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mpn_zero(poly[i], output_limbs + 1);
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limbs_left = total_limbs - (limb_ptr - limbs);
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if (!shift_bits)
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mpn_copyi(poly[i], limb_ptr, limbs_left);
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else
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mpn_rshift(poly[i], limb_ptr, limbs_left, shift_bits);
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return length;
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}
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