163 lines
4.3 KiB
C
163 lines
4.3 KiB
C
/*=============================================================================
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Copyright (C) 2007, 2008 David Harvey (zn_poly)
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Copyright (C) 2013 William Hart
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice, this
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list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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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
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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=============================================================================*/
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#include <stdlib.h>
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#include <gmp.h>
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#include "flint.h"
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#include "nmod_vec.h"
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#include "nmod_poly.h"
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/*
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Same as _nmod_poly_KS2_pack(), but requires b <= FLINT_BITS.
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*/
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void
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_nmod_poly_KS2_pack1(mp_ptr res, mp_srcptr op, slong n, slong s,
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ulong b, ulong k, slong r)
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{
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/* where to write the next limb */
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mp_ptr dest = res;
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/* limb currently being filled */
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mp_limb_t buf;
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/* number of bits used in buf; always in [0, FLINT_BITS) */
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ulong buf_b, buf_b_old;
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/* write leading zero-padding */
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while (k >= FLINT_BITS)
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{
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*dest++ = 0;
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k -= FLINT_BITS;
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}
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buf = 0;
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buf_b = k;
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for (; n > 0; n--, op += s)
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{
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/* put low bits of current input into buffer */
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buf += *op << buf_b;
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buf_b_old = buf_b;
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buf_b += b;
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if (buf_b >= FLINT_BITS)
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{
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/* buffer is full; flush it */
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*dest++ = buf;
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buf_b -= FLINT_BITS;
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/* put remaining bits of current input into buffer */
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buf = buf_b_old ? (*op >> (FLINT_BITS - buf_b_old)) : 0;
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}
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}
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/* write last limb if it's non-empty */
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if (buf_b)
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*dest++ = buf;
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/* zero-pad up to requested length */
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if (r)
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{
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slong written = dest - res;
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for (; written < r; written++)
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*dest++ = 0;
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}
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}
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void
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_nmod_poly_KS2_pack(mp_ptr res, mp_srcptr op, slong n, slong s,
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ulong b, ulong k, slong r)
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{
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/* where to write the next limb */
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mp_ptr dest = res;
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/* limb currently being filled */
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mp_limb_t buf;
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/* number of bits used in buf; always in [0, FLINT_BITS) */
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ulong buf_b, buf_b_old;
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if (b <= FLINT_BITS)
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{
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/* use specialised version if b is small enough */
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_nmod_poly_KS2_pack1(res, op, n, s, b, k, r);
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return;
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}
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/* write leading zero-padding */
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while (k >= FLINT_BITS)
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{
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*dest++ = 0;
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k -= FLINT_BITS;
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}
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buf = 0;
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buf_b = k;
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for (; n > 0; n--, op += s)
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{
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/* put low bits of current input into buffer */
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buf += *op << buf_b;
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buf_b_old = buf_b;
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buf_b += b;
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if (buf_b >= FLINT_BITS)
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{
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/* buffer is full; flush it */
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*dest++ = buf;
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buf_b -= FLINT_BITS;
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/* put remaining bits of current input into buffer */
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buf = buf_b_old ? (*op >> (FLINT_BITS - buf_b_old)) : 0;
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/* write as many extra zeroes as necessary */
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if (buf_b >= FLINT_BITS)
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{
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*dest++ = buf;
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buf = 0;
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buf_b -= FLINT_BITS;
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if (buf_b >= FLINT_BITS)
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{
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*dest++ = 0;
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buf_b -= FLINT_BITS;
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}
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}
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}
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}
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/* write last limb if it's non-empty */
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if (buf_b)
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*dest++ = buf;
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/* zero-pad up to requested length */
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if (r)
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{
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slong written = dest - res;
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for (; written < r; written++)
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*dest++ = 0;
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}
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} |