76 lines
2.4 KiB
C
76 lines
2.4 KiB
C
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/* mpn_mulmid_basecase -- classical middle product algorithm
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Copyright (C) 2009, David Harvey
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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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1. 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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2. 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 HOLDERS 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 "gmp.h"
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#include "gmp-impl.h"
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#include "longlong.h"
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/* Middle product of {up,un} and {vp,vn}, write result to {rp,un-vn+3}.
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Must have un >= vn >= 1.
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Neither input buffer may overlap with the output buffer. */
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void
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mpn_mulmid_basecase (mp_ptr rp,
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mp_srcptr up, mp_size_t un,
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mp_srcptr vp, mp_size_t vn)
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{
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mp_limb_t lo, hi; /* last two limbs of output */
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mp_limb_t temp;
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ASSERT (un >= vn);
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ASSERT (vn >= 1);
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ASSERT (! MPN_OVERLAP_P (rp, un - vn + 3, up, un));
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ASSERT (! MPN_OVERLAP_P (rp, un - vn + 3, vp, vn));
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up += vn - 1;
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un -= vn - 1;
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/* multiply by first limb, store result */
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lo = mpn_mul_1 (rp, up, un, vp[0]);
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hi = 0;
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/* accumulate remaining rows */
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for (vn--; vn; vn--)
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{
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up--, vp++;
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temp = mpn_addmul_1 (rp, up, un, vp[0]);
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add_ssaaaa (hi, lo, hi, lo, 0, temp);
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}
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/* store final limbs */
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#if GMP_NAIL_BITS != 0
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hi = (hi << GMP_NAIL_BITS) + (lo >> GMP_NUMB_BITS);
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lo &= GMP_NUMB_MASK;
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#endif
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rp[un] = lo;
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rp[un + 1] = hi;
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}
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