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Change-Id: Iae65e95cfa0d92091b8b0a424ae36d88efa76aa9 Reviewed-on: https://review.haiku-os.org/c/buildtools/+/3020 Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
65 lines
1.9 KiB
C
65 lines
1.9 KiB
C
/* matrix22_mul1_inverse_vector.c
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THE FUNCTIONS IN THIS FILE ARE INTERNAL WITH MUTABLE INTERFACES. IT IS ONLY
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SAFE TO REACH THEM THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST
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GUARANTEED THAT THEY'LL CHANGE OR DISAPPEAR IN A FUTURE GNU MP RELEASE.
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Copyright 2008, 2010 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of either:
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* the GNU Lesser General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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or
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* the GNU General Public License as published by the Free Software
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Foundation; either version 2 of the License, or (at your option) any
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later version.
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or both in parallel, as here.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received copies of the GNU General Public License and the
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GNU Lesser General Public License along with the GNU MP Library. If not,
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see https://www.gnu.org/licenses/. */
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#include "gmp-impl.h"
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#include "longlong.h"
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/* Sets (r;b) = M^{-1}(a;b), with M^{-1} = (u11, -u01; -u10, u00) from
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the left. Uses three buffers, to avoid a copy. */
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mp_size_t
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mpn_matrix22_mul1_inverse_vector (const struct hgcd_matrix1 *M,
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mp_ptr rp, mp_srcptr ap, mp_ptr bp, mp_size_t n)
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{
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mp_limb_t h0, h1;
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/* Compute (r;b) <-- (u11 a - u01 b; -u10 a + u00 b) as
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r = u11 * a
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r -= u01 * b
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b *= u00
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b -= u10 * a
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*/
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h0 = mpn_mul_1 (rp, ap, n, M->u[1][1]);
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h1 = mpn_submul_1 (rp, bp, n, M->u[0][1]);
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ASSERT (h0 == h1);
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h0 = mpn_mul_1 (bp, bp, n, M->u[0][0]);
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h1 = mpn_submul_1 (bp, ap, n, M->u[1][0]);
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ASSERT (h0 == h1);
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n -= (rp[n-1] | bp[n-1]) == 0;
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return n;
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}
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