From 5aab0cf7b0958c59b21205cf0338fa7c6e324b58 Mon Sep 17 00:00:00 2001
From: Alex Dyachenko <adyache@yahoo.com>
Date: Fri, 28 Jun 2019 12:18:19 -0400
Subject: [PATCH] Corrected mpf_get_2exp_d on Win64 when the exponent in limbs
 fits in mp_bit_cnt but the exponent in bits (as returned by this API) does
 not

---
 mpf/get_d_2exp.c                              |  2 +-
 .../HugeFloatTests/Conversions.cs             | 30 +++++++++++++--
 mpir.net/mpir.net/HugeFloat.h                 |  9 ++---
 tests/mpf/t-get_d_2exp.c                      | 38 +++++++++++++++++++
 4 files changed, 70 insertions(+), 9 deletions(-)

diff --git a/mpf/get_d_2exp.c b/mpf/get_d_2exp.c
index f073bfe2..da54413b 100644
--- a/mpf/get_d_2exp.c
+++ b/mpf/get_d_2exp.c
@@ -47,7 +47,7 @@ mpf_get_2exp_d (double *r, mpf_srcptr src)
 
   *r = mpn_get_d (ptr, abs_size, size,
                     (long) - (abs_size * GMP_NUMB_BITS - cnt));
-  return EXP(src) * GMP_NUMB_BITS - cnt;
+  return (mpir_si)EXP(src) * GMP_NUMB_BITS - cnt;
 }
 
 double
diff --git a/mpir.net/mpir.net-tests/HugeFloatTests/Conversions.cs b/mpir.net/mpir.net-tests/HugeFloatTests/Conversions.cs
index b8767656..b1626199 100644
--- a/mpir.net/mpir.net-tests/HugeFloatTests/Conversions.cs
+++ b/mpir.net/mpir.net-tests/HugeFloatTests/Conversions.cs
@@ -107,7 +107,7 @@ namespace MPIR.Tests.HugeFloatTests
             using (var a = new HugeFloat())
             {
                 a.SetTo(-123.25);
-                var exp = 0;
+                var exp = Platform.Si(0, 0);
                 double c = a.ToDouble(out exp);
                 Assert.IsTrue(c.Equals(-0.962890625));
                 Assert.AreEqual(7L, exp);
@@ -116,6 +116,30 @@ namespace MPIR.Tests.HugeFloatTests
             }
         }
 
+        [TestMethod]
+        public void FloatFromDoubleWithLargeExponent()
+        {
+            using (var a = new HugeFloat())
+            {
+                var exp = Platform.Si(0, 0);
+                double mantissa;
+
+                a.SetTo(3);
+                a.Value = a << Platform.Ui(0x1F65432FD9, 0x7F654329);
+
+                mantissa = a.ToDouble(out exp);
+                Assert.IsTrue(mantissa.Equals(0.75));
+                Assert.AreEqual(Platform.Si(0x1F65432FDB, 0x7F65432B), exp);
+
+                a.SetTo(-3);
+                a.Value = a >> Platform.Ui(0x1F65432FDD, 0x7F65432D);
+
+                mantissa = a.ToDouble(out exp);
+                Assert.IsTrue(mantissa.Equals(-0.75));
+                Assert.AreEqual(Platform.Si(-0x1F65432FDB, -0x7F65432B), exp);
+            }
+        }
+
         [TestMethod]
         public void FloatToAndFromFloat()
         {
@@ -196,12 +220,12 @@ namespace MPIR.Tests.HugeFloatTests
             using(var a = new HugeFloat())
             {
                 a.SetTo(-123.45e20);
-                var exp = 0;
+                var exp = Platform.Si(0, 0);
                 var zillion = Platform.Si(10000000000, 1000000000);
                 a.Value = a + a;
                 double c = a.ToDouble(out exp);
 
-                Assert.AreEqual(75, exp);
+                Assert.AreEqual(Platform.Si(75, 75), exp);
                 c *= Math.Pow(2, exp);
 
                 Assert.IsTrue(a + zillion >= c);
diff --git a/mpir.net/mpir.net/HugeFloat.h b/mpir.net/mpir.net/HugeFloat.h
index 13d16a84..b4336529 100644
--- a/mpir.net/mpir.net/HugeFloat.h
+++ b/mpir.net/mpir.net/HugeFloat.h
@@ -1025,12 +1025,11 @@ namespace MPIR
             /// </para></summary>
             /// <param name="exp">variable to store the exponent in.</param>
             /// <returns>The mantissa of the value as a double, possibly truncated.</returns>
-            double ToDouble([Out] mp_exp_t% exp) 
+            double ToDouble([Out] mpir_si% exp) 
             { 
-                mp_exp_t x; 
-                auto result = MP(get_d_2exp)(&x, _value); 
-                exp = x; 
-                return result; 
+                double x;
+                exp = MP(get_2exp_d)(&x, _value);
+                return x;
             }
 
             #pragma endregion
diff --git a/tests/mpf/t-get_d_2exp.c b/tests/mpf/t-get_d_2exp.c
index 2459fbc5..ac2b9571 100644
--- a/tests/mpf/t-get_d_2exp.c
+++ b/tests/mpf/t-get_d_2exp.c
@@ -109,6 +109,43 @@ check_round (void)
   tests_hardware_setround (old_rnd_mode);
 }
 
+static void
+check_large_exponent(void)
+{
+#ifdef _WIN64
+  static const mpir_si data[] = { 0x1F789ABCDE, 0x1FFFFFFFBF, -0x1FEDCBA987, -0x1FFFFFFFC1 };
+  mpf_t   f;
+  double  got;
+  mpir_si got_exp;
+  unsigned int i;
+
+  mpf_init2 (f, 1024L);
+
+  for (i = 0; i < numberof (data); i++)
+  {
+    mpf_set_ui (f, 1L);
+    if (data[i] > 0)
+    {
+      mpf_mul_2exp(f, f, data[i]);
+    }
+    else
+    {
+      mpf_div_2exp(f, f, -data[i]);
+    }
+    got_exp = mpf_get_2exp_d (&got, f);
+    if (got != 0.5 || got_exp != data[i] + 1)
+    {
+      printf    ("mpf_get_2exp_d bad on 2**%lld\n", data[i]);
+      printf    ("result incorrect, expect mantissa = 0.5, exp = %lld\n", data[i] + 1);
+      mpf_trace ("   f    ", f);
+      d_trace   ("   got  ", got);
+      printf    ("   got exp  %lld\n", got_exp);
+      abort();
+    }
+  }
+  mpf_clear (f);
+#endif
+}
 
 int
 main (void)
@@ -118,6 +155,7 @@ main (void)
 
   check_onebit ();
   check_round ();
+  check_large_exponent ();
 
   tests_end ();
   exit (0);