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Diffstat (limited to 'Build/source/libs/gmp/gmp-6.0.0/mpz/scan1.c')
-rw-r--r--Build/source/libs/gmp/gmp-6.0.0/mpz/scan1.c124
1 files changed, 124 insertions, 0 deletions
diff --git a/Build/source/libs/gmp/gmp-6.0.0/mpz/scan1.c b/Build/source/libs/gmp/gmp-6.0.0/mpz/scan1.c
new file mode 100644
index 00000000000..c9309de6913
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+++ b/Build/source/libs/gmp/gmp-6.0.0/mpz/scan1.c
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+/* mpz_scan1 -- search for a 1 bit.
+
+Copyright 2000-2002, 2004, 2012 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+it under the terms of either:
+
+ * the GNU Lesser General Public License as published by the Free
+ Software Foundation; either version 3 of the License, or (at your
+ option) any later version.
+
+or
+
+ * the GNU General Public License as published by the Free Software
+ Foundation; either version 2 of the License, or (at your option) any
+ later version.
+
+or both in parallel, as here.
+
+The GNU MP Library is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+for more details.
+
+You should have received copies of the GNU General Public License and the
+GNU Lesser General Public License along with the GNU MP Library. If not,
+see https://www.gnu.org/licenses/. */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+#include "longlong.h"
+
+
+/* mpn_scan0 can't be used for the inverted u<0 search since there might not
+ be a 0 bit before the end of the data. mpn_scan1 could be used under u>0
+ (except when in the high limb), but usually the search won't go very far
+ so it seems reasonable to inline that code. */
+
+mp_bitcnt_t
+mpz_scan1 (mpz_srcptr u, mp_bitcnt_t starting_bit) __GMP_NOTHROW
+{
+ mp_srcptr u_ptr = PTR(u);
+ mp_size_t size = SIZ(u);
+ mp_size_t abs_size = ABS(size);
+ mp_srcptr u_end = u_ptr + abs_size - 1;
+ mp_size_t starting_limb = starting_bit / GMP_NUMB_BITS;
+ mp_srcptr p = u_ptr + starting_limb;
+ mp_limb_t limb;
+ int cnt;
+
+ /* Past the end there's no 1 bits for u>=0, or an immediate 1 bit for u<0.
+ Notice this test picks up any u==0 too. */
+ if (starting_limb >= abs_size)
+ return (size >= 0 ? ~(mp_bitcnt_t) 0 : starting_bit);
+
+ /* This is an important case, where sign is not relevant! */
+ if (starting_bit == 0)
+ goto short_cut;
+
+ limb = *p;
+
+ if (size >= 0)
+ {
+ /* Mask to 0 all bits before starting_bit, thus ignoring them. */
+ limb &= (MP_LIMB_T_MAX << (starting_bit % GMP_NUMB_BITS));
+
+ if (limb == 0)
+ {
+ /* If it's the high limb which is zero after masking, then there's
+ no 1 bits after starting_bit. */
+ if (p == u_end)
+ return ~(mp_bitcnt_t) 0;
+
+ /* Otherwise search further for a non-zero limb. The high limb is
+ non-zero, if nothing else. */
+ search_nonzero:
+ do
+ {
+ ASSERT (p != u_end);
+ p++;
+ short_cut:
+ limb = *p;
+ }
+ while (limb == 0);
+ }
+ }
+ else
+ {
+ /* If there's a non-zero limb before ours then we're in the ones
+ complement region. */
+ if (mpn_zero_p (u_ptr, starting_limb)) {
+ if (limb == 0)
+ /* Seeking for the first non-zero bit, it is the same for u and -u. */
+ goto search_nonzero;
+
+ /* Adjust so ~limb implied by searching for 0 bit becomes -limb. */
+ limb--;
+ }
+
+ /* Now seeking a 0 bit. */
+
+ /* Mask to 1 all bits before starting_bit, thus ignoring them. */
+ limb |= (CNST_LIMB(1) << (starting_bit % GMP_NUMB_BITS)) - 1;
+
+ /* Search for a limb which is not all ones. If the end is reached
+ then the zero immediately past the end is the result. */
+ while (limb == GMP_NUMB_MAX)
+ {
+ if (p == u_end)
+ return (mp_bitcnt_t) abs_size * GMP_NUMB_BITS;
+ p++;
+ limb = *p;
+ }
+
+ /* Now seeking low 1 bit. */
+ limb = ~limb;
+ }
+
+ ASSERT (limb != 0);
+ count_trailing_zeros (cnt, limb);
+ return (mp_bitcnt_t) (p - u_ptr) * GMP_NUMB_BITS + cnt;
+}