284 lines
6.9 KiB
C
284 lines
6.9 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_unpack(), but requires b <= FLINT_BITS
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(i.e. writes one word per coefficient)
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*/
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void
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_nmod_poly_KS2_unpack1(mp_ptr res, mp_srcptr op, slong n, ulong b,
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ulong k)
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{
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/* limb we're currently extracting bits from */
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mp_limb_t buf = 0;
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/* number of bits currently in buf; always in [0, FLINT_BITS) */
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ulong buf_b = 0;
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/* skip over k leading bits */
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while (k >= FLINT_BITS)
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{
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k -= FLINT_BITS;
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op++;
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}
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if (k)
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{
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buf = *op++;
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buf >>= k;
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buf_b = FLINT_BITS - k;
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}
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if (b == FLINT_BITS)
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{
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/* various special cases */
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if (buf_b)
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{
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for (; n > 0; n--)
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{
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/* we need bits from both sides of a limb boundary */
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ulong temp = buf;
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buf = *op++;
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*res++ = temp + (buf << buf_b);
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buf >>= (FLINT_BITS - buf_b);
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}
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}
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else
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{
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for (; n > 0; n--)
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*res++ = *op++;
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}
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}
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else
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{
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ulong mask = (UWORD(1) << b) - 1;
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for (; n > 0; n--)
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{
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if (b <= buf_b)
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{
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/* buf contains all the bits we need */
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*res++ = buf & mask;
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buf >>= b;
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buf_b -= b;
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}
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else
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{
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/* we need bits from both sides of a limb boundary */
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ulong temp = buf;
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buf = *op++;
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*res++ = temp + ((buf << buf_b) & mask);
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buf >>= (b - buf_b);
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buf_b = FLINT_BITS - (b - buf_b);
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}
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}
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}
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}
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/*
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Same as _nmod_poly_KS2_unpack(), but requires FLINT_BITS < b <= 2 * FLINT_BITS
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(i.e. writes two words per coefficient)
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*/
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void
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_nmod_poly_KS2_unpack2(mp_ptr res, mp_srcptr op, slong n, ulong b,
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ulong k)
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{
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/* limb we're currently extracting bits from */
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mp_limb_t buf = 0;
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/* number of bits currently in buf; always in [0, FLINT_BITS) */
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ulong buf_b = 0;
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/* skip over k leading bits */
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while (k >= FLINT_BITS)
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{
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k -= FLINT_BITS;
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op++;
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}
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if (k)
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{
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buf = *op++;
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buf >>= k;
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buf_b = FLINT_BITS - k;
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}
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if (b == 2 * FLINT_BITS)
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{
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n *= 2;
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/* various special cases */
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if (buf_b)
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{
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for (; n > 0; n--)
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{
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/* we need bits from both sides of a limb boundary */
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ulong temp = buf;
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buf = *op++;
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*res++ = temp + (buf << buf_b);
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buf >>= (FLINT_BITS - buf_b);
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}
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}
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else
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{
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for (; n > 0; n--)
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*res++ = *op++;
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}
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}
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else
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{
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ulong mask;
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b -= FLINT_BITS;
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mask = (UWORD(1) << b) - 1;
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for (; n > 0; n--)
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{
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/* shunt one whole limb through first */
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if (buf_b)
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{
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ulong temp = buf;
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buf = *op++;
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*res++ = temp + (buf << buf_b);
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buf >>= (FLINT_BITS - buf_b);
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}
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else
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*res++ = *op++;
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/* now handle the fractional limb */
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if (b <= buf_b)
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{
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/* buf contains all the bits we need */
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*res++ = buf & mask;
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buf >>= b;
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buf_b -= b;
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}
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else
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{
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/* we need bits from both sides of a limb boundary */
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ulong temp = buf;
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buf = *op++;
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*res++ = temp + ((buf << buf_b) & mask);
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buf >>= (b - buf_b);
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buf_b = FLINT_BITS - (b - buf_b);
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}
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}
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}
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}
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/*
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Same as _nmod_poly_KS2_unpack(), but requires 2 * FLINT_BITS < b < 3 * FLINT_BITS
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(i.e. writes three words per coefficient)
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*/
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void
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_nmod_poly_KS2_unpack3(mp_ptr res, mp_srcptr op, slong n, ulong b,
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ulong k)
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{
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/* limb we're currently extracting bits from */
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mp_limb_t buf = 0;
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/* number of bits currently in buf; always in [0, FLINT_BITS) */
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ulong buf_b = 0, mask;
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/* skip over k leading bits */
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while (k >= FLINT_BITS)
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{
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k -= FLINT_BITS;
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op++;
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}
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if (k)
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{
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buf = *op++;
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buf >>= k;
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buf_b = FLINT_BITS - k;
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}
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b -= 2 * FLINT_BITS;
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mask = (UWORD(1) << b) - 1;
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for (; n > 0; n--)
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{
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/* shunt two whole limbs through first */
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if (buf_b)
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{
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ulong temp = buf;
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buf = *op++;
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*res++ = temp + (buf << buf_b);
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buf >>= (FLINT_BITS - buf_b);
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temp = buf;
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buf = *op++;
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*res++ = temp + (buf << buf_b);
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buf >>= (FLINT_BITS - buf_b);
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}
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else
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{
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*res++ = *op++;
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*res++ = *op++;
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}
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/* now handle the fractional limb */
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if (b <= buf_b)
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{
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/* buf contains all the bits we need */
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*res++ = buf & mask;
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buf >>= b;
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buf_b -= b;
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}
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else
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{
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/* we need bits from both sides of a limb boundary */
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ulong temp = buf;
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buf = *op++;
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*res++ = temp + ((buf << buf_b) & mask);
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buf >>= (b - buf_b);
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buf_b = FLINT_BITS - (b - buf_b);
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}
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}
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}
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void
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_nmod_poly_KS2_unpack(mp_ptr res, mp_srcptr op, slong n, ulong b,
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ulong k)
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{
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if (b <= FLINT_BITS)
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_nmod_poly_KS2_unpack1 (res, op, n, b, k);
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else if (b <= 2 * FLINT_BITS)
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_nmod_poly_KS2_unpack2 (res, op, n, b, k);
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else /* b < 3 * FLINT_BITS */
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_nmod_poly_KS2_unpack3 (res, op, n, b, k);
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} |