Reorganisation of the source tree

[ghc-hetmet.git] / rts / gmp / mpn / generic / mod_1_rs.c

diff --git a/rts/gmp/mpn/generic/mod_1_rs.c b/rts/gmp/mpn/generic/mod_1_rs.c
new file mode 100644 (file)
index 0000000..62aaa94
--- /dev/null
+++ b/rts/gmp/mpn/generic/mod_1_rs.c
@@ -0,0 +1,111 @@
+/* mpn_mod_1_rshift -- mpn remainder under hypothetical right shift.
+
+   THE FUNCTION IN THIS FILE IS FOR INTERNAL USE AND HAS A MUTABLE
+   INTERFACE.  IT IS ONLY SAFE TO REACH IT THROUGH DOCUMENTED INTERFACES.
+   IT'S ALMOST GUARANTEED THAT IT'LL CHANGE OR DISAPPEAR IN A FUTURE GNU MP
+   RELEASE. */
+
+/*
+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"
+
+
+/* When testing on a CPU with UDIV_NEEDS_NORMALIZATION equal to 0, it can be
+   changed to 1 temporarily to test the code under that case too. */
+#if 0
+#undef UDIV_NEEDS_NORMALIZATION
+#define UDIV_NEEDS_NORMALIZATION 1
+#endif
+
+
+/* Calculate the remainder "(ptr,size >> shift) % divisor".  Note ptr,size
+   is unchanged, the shift is only for its effect on the remainder.
+   The shift doesn't even need to be considered until the last limb.
+
+   This function has the normal size!=0 restriction, unlike the basic
+   mpn_mod_1. */
+
+mp_limb_t
+#if __STDC__
+mpn_mod_1_rshift (mp_srcptr ptr, mp_size_t size, unsigned shift,
+                  mp_limb_t divisor)
+#else
+mpn_mod_1_rshift (ptr, size, shift, divisor)
+     mp_srcptr ptr;
+     mp_size_t size;
+     unsigned  shift;
+     mp_limb_t divisor;
+#endif
+{
+  mp_limb_t  quot, rem;
+
+  ASSERT (shift >= 1);
+  ASSERT (shift < BITS_PER_MP_LIMB);
+  ASSERT (size >= 1);
+
+  if (size == 1)
+    return (ptr[0] >> shift) % divisor;
+
+#if UDIV_NEEDS_NORMALIZATION 
+  {
+    int  norm;
+    int  delta;
+
+    count_leading_zeros (norm, divisor);
+    divisor <<= norm;
+
+    delta = shift - norm;
+    if (delta == 0)
+      return mpn_mod_1 (ptr, size, divisor) >> norm;
+
+    if (delta > 0)
+      {
+        rem = mpn_mod_1 (ptr+1, size-1, divisor);
+        udiv_qrnnd (quot, rem,
+                    rem >> delta,
+                    (rem << (BITS_PER_MP_LIMB-delta)) | (ptr[0] >> delta),
+                    divisor);
+        return rem >> norm;
+      }
+    else
+      {
+        rem = mpn_mod_1 (ptr, size, divisor);
+        udiv_qrnnd (quot, rem,
+                    rem >> (BITS_PER_MP_LIMB+delta),
+                    rem << -delta,
+                    divisor);
+        return rem >> norm;
+      }
+  }
+
+#else /* !UDIV_NEEDS_NORMALIZATION */
+
+  rem = mpn_mod_1 (ptr+1, size-1, divisor);
+  udiv_qrnnd (quot, rem,
+              rem >> shift,
+              (rem << (BITS_PER_MP_LIMB-shift)) | (ptr[0] >> shift),
+              divisor);
+  return rem;
+
+#endif
+}