[project @ 1996-01-08 20:28:12 by partain]

[ghc-hetmet.git] / ghc / runtime / gmp / mpz_dmincl.c

diff --git a/ghc/runtime/gmp/mpz_dmincl.c b/ghc/runtime/gmp/mpz_dmincl.c
new file mode 100644 (file)
index 0000000..dde7981
--- /dev/null
+++ b/ghc/runtime/gmp/mpz_dmincl.c
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+/* mpz_dmincl.c -- include file for mpz_dm.c, mpz_mod.c, mdiv.c.
+
+Copyright (C) 1991 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 General Public License as published by
+the Free Software Foundation; either version 2, 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 General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with the GNU MP Library; see the file COPYING.  If not, write to
+the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+/* THIS CODE IS OBSOLETE.  IT WILL SOON BE REPLACED BY CLEANER CODE WITH
+   LESS MEMORY ALLOCATION OVERHEAD.  */
+
+/* If den == quot, den needs temporary storage.
+   If den == rem, den needs temporary storage.
+   If num == quot, num needs temporary storage.
+   If den has temporary storage, it can be normalized while being copied,
+     i.e no extra storage should be allocated.  */
+
+/* This is the function body of mdiv, mpz_divmod, and mpz_mod.
+
+   If COMPUTE_QUOTIENT is defined, the quotient is put in the MP_INT
+   object quot, otherwise that variable is not referenced at all.
+
+   The remainder is always computed, and the result is put in the MP_INT
+   object rem.  */
+
+{
+  mp_ptr np, dp;
+  mp_ptr qp, rp;
+  mp_size nsize = num->size;
+  mp_size dsize = den->size;
+  mp_size qsize, rsize;
+  mp_size sign_remainder = nsize;
+#ifdef COMPUTE_QUOTIENT
+  mp_size sign_quotient = nsize ^ dsize;
+#endif
+  unsigned normalization_steps;
+
+  nsize = ABS (nsize);
+  dsize = ABS (dsize);
+
+  /* Ensure space is enough for quotient and remainder. */
+
+  /* We need space for an extra limb in the remainder, because it's
+     up-shifted (normalized) below.  */
+  rsize = nsize + 1;
+  if (rem->alloc < rsize)
+    _mpz_realloc (rem, rsize);
+
+  qsize = nsize - dsize + 1;   /* qsize cannot be bigger than this.  */
+  if (qsize <= 0)
+    {
+#ifdef COMPUTE_QUOTIENT
+      quot->size = 0;
+#endif
+      if (num != rem)
+       {
+         rem->size = num->size;
+         MPN_COPY (rem->d, num->d, nsize);
+       }
+      return;
+    }
+
+#ifdef COMPUTE_QUOTIENT
+  if (quot->alloc < qsize)
+    _mpz_realloc (quot, qsize);
+  qp = quot->d;
+#else
+  qp = (mp_ptr) alloca (qsize * BYTES_PER_MP_LIMB);
+#endif
+  np = num->d;
+  dp = den->d;
+  rp = rem->d;
+
+  /* Make sure quot and num are different.  Otherwise the numerator
+     would be successively overwritten by the quotient digits.  */
+  if (qp == np)
+    {
+      np = (mp_ptr) alloca (nsize * BYTES_PER_MP_LIMB);
+      MPN_COPY (np, qp, nsize);
+    }
+
+  count_leading_zeros (normalization_steps, dp[dsize - 1]);
+
+  /* Normalize the denominator, i.e. make its most significant bit set by
+     shifting it NORMALIZATION_STEPS bits to the left.  Also shift the
+     numerator the same number of steps (to keep the quotient the same!).  */
+  if (normalization_steps != 0)
+    {
+      mp_ptr tp;
+      mp_limb ndigit;
+
+      /* Shift up the denominator setting the most significant bit of
+        the most significant word.  Use temporary storage not to clobber
+        the original contents of the denominator.  */
+      tp = (mp_ptr) alloca (dsize * BYTES_PER_MP_LIMB);
+      (void) mpn_lshift (tp, dp, dsize, normalization_steps);
+      dp = tp;
+
+      /* Shift up the numerator, possibly introducing a new most
+        significant word.  Move the shifted numerator in the remainder
+        meanwhile.  */
+      ndigit = mpn_lshift (rp, np, nsize, normalization_steps);
+      if (ndigit != 0)
+       {
+         rp[nsize] = ndigit;
+         rsize = nsize + 1;
+       }
+      else
+       rsize = nsize;
+    }
+  else
+    {
+#ifdef COMPUTE_QUOTIENT
+      if (rem == den || quot == den)
+#else
+      if (rem == den)
+#endif
+       {
+         mp_ptr tp;
+
+         tp = (mp_ptr) alloca (dsize * BYTES_PER_MP_LIMB);
+         MPN_COPY (tp, dp, dsize);
+         dp = tp;
+       }
+
+      /* Move the numerator to the remainder.  */
+      if (rp != np)
+       MPN_COPY (rp, np, nsize);
+
+      rsize = nsize;
+    }
+
+  qsize = rsize - dsize + mpn_div (qp, rp, rsize, dp, dsize);
+
+  rsize = dsize;
+
+  /* Normalize the remainder.  */
+  while (rsize > 0)
+    {
+      if (rp[rsize - 1] != 0)
+       break;
+      rsize--;
+    }
+
+  if (normalization_steps != 0)
+    rsize = mpn_rshift (rp, rp, rsize, normalization_steps);
+
+  rem->size = (sign_remainder >= 0) ? rsize : -rsize;
+
+#ifdef COMPUTE_QUOTIENT
+  /* Normalize the quotient.  We may have at most one leading
+     zero-word, so no loop is needed.  */
+  if (qsize > 0)
+    qsize -= (qp[qsize - 1] == 0);
+
+  quot->size = (sign_quotient >= 0) ? qsize : -qsize;
+#endif
+
+  alloca (0);
+}