Merge remote-tracking branch 'origin/master' into feature/bignum

1 files changed, 16 insertions, 32 deletions

diff --git a/src/print.c b/src/print.c
index 998ff2dc0c6..3819c505b12 100644
--- a/src/print.c
+++ b/src/print.c
@@ -38,6 +38,11 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 #include <c-ctype.h>
 #include <float.h>
 #include <ftoastr.h>
+#include <math.h>
+
+#if IEEE_FLOATING_POINT
+# include <ieee754.h>
+#endif
 
 #ifdef WINDOWSNT
 # include <sys/socket.h> /* for F_DUPFD_CLOEXEC */
@@ -1001,43 +1006,22 @@ float_to_string (char *buf, double data)
   int width;
   int len;
 
-  /* Check for plus infinity in a way that won't lose
-     if there is no plus infinity.  */
-  if (data == data / 2 && data > 1.0)
-    {
-      static char const infinity_string[] = "1.0e+INF";
-      strcpy (buf, infinity_string);
-      return sizeof infinity_string - 1;
-    }
-  /* Likewise for minus infinity.  */
-  if (data == data / 2 && data < -1.0)
+  if (isinf (data))
     {
       static char const minus_infinity_string[] = "-1.0e+INF";
-      strcpy (buf, minus_infinity_string);
-      return sizeof minus_infinity_string - 1;
+      bool positive = 0 < data;
+      strcpy (buf, minus_infinity_string + positive);
+      return sizeof minus_infinity_string - 1 - positive;
     }
-  /* Check for NaN in a way that won't fail if there are no NaNs.  */
-  if (! (data * 0.0 >= 0.0))
+#if IEEE_FLOATING_POINT
+  if (isnan (data))
     {
-      /* Prepend "-" if the NaN's sign bit is negative.
-         The sign bit of a double is the bit that is 1 in -0.0.  */
-      static char const NaN_string[] = "0.0e+NaN";
-      int i;
-      union { double d; char c[sizeof (double)]; } u_data, u_minus_zero;
-      bool negative = 0;
-      u_data.d = data;
-      u_minus_zero.d = - 0.0;
-      for (i = 0; i < sizeof (double); i++)
-        if (u_data.c[i] & u_minus_zero.c[i])
-          {
-            *buf = '-';
-            negative = 1;
-            break;
-          }
-
-      strcpy (buf + negative, NaN_string);
-      return negative + sizeof NaN_string - 1;
+      union ieee754_double u = { .d = data };
+      uprintmax_t hi = u.ieee_nan.mantissa0;
+      return sprintf (buf, &"-%"pMu".0e+NaN"[!u.ieee_nan.negative],
+                      (hi << 31 << 1) + u.ieee_nan.mantissa1);
     }
+#endif
 
   if (NILP (Vfloat_output_format)
       || !STRINGP (Vfloat_output_format))