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-rw-r--r--vendor/gmp-6.3.0/mpz/kronsz.c137
1 files changed, 137 insertions, 0 deletions
diff --git a/vendor/gmp-6.3.0/mpz/kronsz.c b/vendor/gmp-6.3.0/mpz/kronsz.c
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+/* mpz_si_kronecker -- long+mpz Kronecker/Jacobi symbol.
+
+Copyright 1999-2002 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-impl.h"
+#include "longlong.h"
+
+
+int
+mpz_si_kronecker (long a, mpz_srcptr b)
+{
+ mp_srcptr b_ptr;
+ mp_limb_t b_low;
+ mp_size_t b_size;
+ mp_size_t b_abs_size;
+ mp_limb_t a_limb, b_rem;
+ unsigned twos;
+ int result_bit1;
+
+#if GMP_NUMB_BITS < BITS_PER_ULONG
+ if (a > GMP_NUMB_MAX || a < -GMP_NUMB_MAX)
+ {
+ mp_limb_t alimbs[2];
+ mpz_t az;
+ ALLOC(az) = numberof (alimbs);
+ PTR(az) = alimbs;
+ mpz_set_si (az, a);
+ return mpz_kronecker (az, b);
+ }
+#endif
+
+ b_size = SIZ (b);
+ if (b_size == 0)
+ return JACOBI_S0 (a); /* (a/0) */
+
+ /* account for the effect of the sign of b, then ignore it */
+ result_bit1 = JACOBI_BSGN_SS_BIT1 (a, b_size);
+
+ b_ptr = PTR(b);
+ b_low = b_ptr[0];
+ b_abs_size = ABS (b_size);
+
+ if ((b_low & 1) != 0)
+ {
+ /* b odd */
+
+ result_bit1 ^= JACOBI_ASGN_SU_BIT1 (a, b_low);
+ a_limb = ABS_CAST(mp_limb_t, a);
+
+ if ((a_limb & 1) == 0)
+ {
+ /* (0/b)=1 for b=+/-1, 0 otherwise */
+ if (a_limb == 0)
+ return (b_abs_size == 1 && b_low == 1);
+
+ /* a even, b odd */
+ count_trailing_zeros (twos, a_limb);
+ a_limb >>= twos;
+ /* (a*2^n/b) = (a/b) * twos(n,a) */
+ result_bit1 ^= JACOBI_TWOS_U_BIT1 (twos, b_low);
+ }
+ }
+ else
+ {
+ /* (even/even)=0, and (0/b)=0 for b!=+/-1 */
+ if ((a & 1) == 0)
+ return 0;
+
+ /* a odd, b even
+
+ Establish shifted b_low with valid bit1 for ASGN and RECIP below.
+ Zero limbs stripped are accounted for, but zero bits on b_low are
+ not because they remain in {b_ptr,b_abs_size} for the
+ JACOBI_MOD_OR_MODEXACT_1_ODD. */
+
+ JACOBI_STRIP_LOW_ZEROS (result_bit1, a, b_ptr, b_abs_size, b_low);
+ if ((b_low & 1) == 0)
+ {
+ if (UNLIKELY (b_low == GMP_NUMB_HIGHBIT))
+ {
+ /* need b_ptr[1] to get bit1 in b_low */
+ if (b_abs_size == 1)
+ {
+ /* (a/0x80000000) = (a/2)^(BPML-1) */
+ if ((GMP_NUMB_BITS % 2) == 0)
+ result_bit1 ^= JACOBI_TWO_U_BIT1 (a);
+ return JACOBI_BIT1_TO_PN (result_bit1);
+ }
+
+ /* b_abs_size > 1 */
+ b_low = b_ptr[1] << 1;
+ }
+ else
+ {
+ count_trailing_zeros (twos, b_low);
+ b_low >>= twos;
+ }
+ }
+
+ result_bit1 ^= JACOBI_ASGN_SU_BIT1 (a, b_low);
+ a_limb = (unsigned long) ABS(a);
+ }
+
+ if (a_limb == 1)
+ return JACOBI_BIT1_TO_PN (result_bit1); /* (1/b)=1 */
+
+ /* (a/b*2^n) = (b*2^n mod a / a) * recip(a,b) */
+ JACOBI_MOD_OR_MODEXACT_1_ODD (result_bit1, b_rem, b_ptr, b_abs_size, a_limb);
+ result_bit1 ^= JACOBI_RECIP_UU_BIT1 (a_limb, b_low);
+ return mpn_jacobi_base (b_rem, a_limb, result_bit1);
+}