Imported gcc-4.4.3

[msp430-gcc.git] / gmp / mpz / kronuz.c

diff --git a/gmp/mpz/kronuz.c b/gmp/mpz/kronuz.c
new file mode 100644 (file)
index 0000000..82a9962
--- /dev/null
+++ b/gmp/mpz/kronuz.c
@@ -0,0 +1,119 @@
+/* mpz_ui_kronecker -- ulong+mpz Kronecker/Jacobi symbol.
+
+Copyright 1999, 2000, 2001, 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 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.
+
+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.  If not, see http://www.gnu.org/licenses/.  */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+#include "longlong.h"
+
+
+int
+mpz_ui_kronecker (unsigned long a, mpz_srcptr b)
+{
+  mp_srcptr  b_ptr;
+  mp_limb_t  b_low;
+  int        b_abs_size;
+  mp_limb_t  b_rem;
+  int        twos;
+  int        result_bit1;
+
+  /* (a/-1)=1 when a>=0, so the sign of b is ignored */
+  b_abs_size = ABSIZ (b);
+
+  if (b_abs_size == 0)
+    return JACOBI_U0 (a);  /* (a/0) */
+
+  if (a > GMP_NUMB_MAX)
+    {
+      mp_limb_t  alimbs[2];
+      mpz_t      az;
+      ALLOC(az) = numberof (alimbs);
+      PTR(az) = alimbs;
+      mpz_set_ui (az, a);
+      return mpz_kronecker (az, b);
+    }
+
+  b_ptr = PTR(b);
+  b_low = b_ptr[0];
+  result_bit1 = 0;
+
+  if (! (b_low & 1))
+    {
+      /* (0/b)=0 for b!=+/-1; and (even/even)=0 */
+      if (! (a & 1))
+        return 0;
+
+      /* a odd, b even
+
+         Establish shifted b_low with valid bit1 for the 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
+         JACOBI_MOD_OR_MODEXACT_1_ODD. */
+
+      JACOBI_STRIP_LOW_ZEROS (result_bit1, a, b_ptr, b_abs_size, b_low);
+      if (! (b_low & 1))
+        {
+          if (UNLIKELY (b_low == GMP_NUMB_HIGHBIT))
+            {
+              /* need b_ptr[1] to get bit1 in b_low */
+              if (b_abs_size == 1)
+                {
+                  /* (a/0x80...00) == (a/2)^(NUMB-1) */
+                  if ((GMP_NUMB_BITS % 2) == 0)
+                    {
+                      /* JACOBI_STRIP_LOW_ZEROS does nothing to result_bit1
+                         when GMP_NUMB_BITS is even, so it's still 0. */
+                      ASSERT (result_bit1 == 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;
+            }
+        }
+    }
+  else
+    {
+      if (a == 0)        /* (0/b)=1 for b=+/-1, 0 otherwise */
+        return (b_abs_size == 1 && b_low == 1);
+
+      if (! (a & 1))
+        {
+          /* a even, b odd */
+          count_trailing_zeros (twos, a);
+          a >>= twos;
+          /* (a*2^n/b) = (a/b) * (2/a)^n */
+          result_bit1 = JACOBI_TWOS_U_BIT1 (twos, b_low);
+        }
+    }
+
+  if (a == 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);
+  result_bit1 ^= JACOBI_RECIP_UU_BIT1 (a, b_low);
+  return mpn_jacobi_base (b_rem, (mp_limb_t) a, result_bit1);
+}