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Diffstat (limited to 'rts/gmp/mpz/kronzs.c')
-rw-r--r--rts/gmp/mpz/kronzs.c74
1 files changed, 74 insertions, 0 deletions
diff --git a/rts/gmp/mpz/kronzs.c b/rts/gmp/mpz/kronzs.c
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+/* mpz_kronecker_si -- Kronecker/Jacobi symbol. */
+
+/*
+Copyright (C) 1999, 2000 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 the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or (at your
+option) any later version.
+
+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 Lesser General Public
+License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with the GNU MP Library; see the file COPYING.LIB. If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+MA 02111-1307, USA.
+*/
+
+#include "gmp.h"
+#include "gmp-impl.h"
+#include "longlong.h"
+
+
+/* This function is expected to be often used with b odd, so there's a test
+ for this before invoking count_trailing_zeros().
+
+ After the absolute value of b is established it's treated as an unsigned
+ long, because 0x80..00 doesn't fit in a signed long. */
+
+int
+#if __STDC__
+mpz_kronecker_si (mpz_srcptr a, long b)
+#else
+mpz_kronecker_si (a, b)
+ mpz_srcptr a;
+ long b;
+#endif
+{
+ int result_bit1;
+ int twos;
+
+ if (b == 0)
+ return JACOBI_Z0 (a);
+
+ result_bit1 = JACOBI_BSGN_ZS_BIT1(a, b);
+ b = ABS (b);
+
+ if (b == 1)
+ return JACOBI_BIT1_TO_PN (result_bit1); /* (a/1) = 1 for any a */
+
+ if (b & 1)
+ return mpn_jacobi_base (mpz_fdiv_ui (a, b), b, result_bit1);
+
+ /* result 0 if both a,b even */
+ if (mpz_even_p (a))
+ return 0;
+
+ /* (a/2)=(2/a) when a odd */
+ count_trailing_zeros (twos, b);
+ result_bit1 ^= JACOBI_TWOS_U_BIT1 (twos, PTR(a)[0]);
+
+ b = ((unsigned long) b) >> twos;
+ if (b == 1)
+ return JACOBI_BIT1_TO_PN (result_bit1);
+ else
+ return mpn_jacobi_base (mpz_fdiv_ui (a, b), b, result_bit1);
+}
+
+