1 files changed, 107 insertions, 0 deletions
diff --git a/src/fits_intmax.c b/src/fits_intmax.c
new file mode 100644
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--- /dev/null
+++ b/src/fits_intmax.c
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+/* mpfr_fits_intmax_p -- test whether an mpfr fits an intmax_t.
+
+Copyright 2004, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc.
+Contributed by the AriC and Caramel projects, INRIA.
+
+This file is part of the GNU MPFR Library.
+
+The GNU MPFR 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 MPFR 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 MPFR Library; see the file COPYING.LESSER.  If not, see
+http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
+51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"            /* for a build within gmp */
+#endif
+
+#include "mpfr-intmax.h"
+#include "mpfr-impl.h"
+
+#ifdef _MPFR_H_HAVE_INTMAX_T
+
+/* We can't use fits_s.h <= mpfr_cmp_ui */
+int
+mpfr_fits_intmax_p (mpfr_srcptr f, mpfr_rnd_t rnd)
+{
+  mpfr_exp_t e;
+  int prec;
+  mpfr_t x, y;
+  int neg;
+  int res;
+
+  if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (f)))
+    /* Zero always fit */
+    return MPFR_IS_ZERO (f) ? 1 : 0;
+
+  /* now it fits if either
+     (a) MINIMUM <= f <= MAXIMUM
+     (b) or MINIMUM <= round(f, prec(slong), rnd) <= MAXIMUM */
+
+  e = MPFR_EXP (f);
+  if (e < 1)
+    return 1; /* |f| < 1: always fits */
+
+  neg = MPFR_IS_NEG (f);
+
+  /* let EXTREMUM be MAXIMUM if f > 0, and MINIMUM if f < 0 */
+
+  /* first compute prec(EXTREMUM), this could be done at configure time,
+     but the result can depend on neg (the loop is moved inside the "if"
+     to give the compiler a better chance to compute prec statically) */
+  if (neg)
+    {
+      uintmax_t s;
+      /* In C89, the division on negative integers isn't well-defined. */
+      s = SAFE_ABS (uintmax_t, MPFR_INTMAX_MIN);
+      for (prec = 0; s != 0; s /= 2, prec ++);
+    }
+  else
+    {
+      intmax_t s;
+      s = MPFR_INTMAX_MAX;
+      for (prec = 0; s != 0; s /= 2, prec ++);
+    }
+
+  /* EXTREMUM needs prec bits, i.e. 2^(prec-1) <= |EXTREMUM| < 2^prec */
+
+   /* if e <= prec - 1, then f < 2^(prec-1) <= |EXTREMUM| */
+  if (e <= prec - 1)
+    return 1;
+
+  /* if e >= prec + 1, then f >= 2^prec > |EXTREMUM| */
+  if (e >= prec + 1)
+    return 0;
+
+  MPFR_ASSERTD (e == prec);
+
+  /* hard case: first round to prec bits, then check */
+  mpfr_init2 (x, prec);
+  mpfr_set (x, f, rnd);
+
+  if (neg)
+    {
+      mpfr_init2 (y, prec);
+      mpfr_set_sj (y, MPFR_INTMAX_MIN, MPFR_RNDN);
+      res = mpfr_cmp (x, y) >= 0;
+      mpfr_clear (y);
+    }
+  else
+    {
+      res = MPFR_GET_EXP (x) == e;
+    }
+
+  mpfr_clear (x);
+  return res;
+}
+
+#endif