power-ieee128: Fix up byte-swapping for IBM extended real(kind=16)

Here is a patch to fix up the ppc64be vs. ppc64le byteswapping
of IBM extended real(kind=16) and complex(kind=16).
Similarly to the BT_COMPLEX case it halves size and doubles nelems
for the bswap_array calls.  Of course for r16_ibm and r16_ieee conversions
one needs to make sure it is only done when the on file data is in that
format and not in IEEE quad.

2022-01-11  Jakub Jelinek  <jakub@redhat.com>

	* io/transfer.c (unformatted_read, unformatted_write): When
	byteswapping IBM extended real(kind=16), handle it as byteswapping
	two real(kind=8) values.

diff --git a/libgfortran/io/transfer.c b/libgfortran/io/transfer.c
index 8e4f64d..f543dfd 100644 (file)
--- a/libgfortran/io/transfer.c
+++ b/libgfortran/io/transfer.c
@@ -1145,11 +1145,28 @@ unformatted_read (st_parameter_dt *dtp, bt type,
          size /= 2;
        }
 #ifndef HAVE_GFC_REAL_17
+#if defined(HAVE_GFC_REAL_16) && GFC_REAL_16_DIGITS == 106
+      /* IBM extended format is stored as a pair of IEEE754
+        double values, with the more significant value first
+        in both big and little endian.  */
+      if (kind == 16 && (type == BT_REAL || type == BT_COMPLEX))
+       {
+         nelems *= 2;
+         size /= 2;
+       }
+#endif
       bswap_array (dest, dest, size, nelems);
 #else
       unit_convert bswap = convert & ~(GFC_CONVERT_R16_IEEE | GFC_CONVERT_R16_IBM);
       if (bswap == GFC_CONVERT_SWAP)
-       bswap_array (dest, dest, size, nelems);
+       {
+         if ((type == BT_REAL || type == BT_COMPLEX)
+             && ((kind == 16 && (convert & GFC_CONVERT_R16_IEEE) == 0)
+                 || (kind == 17 && (convert & GFC_CONVERT_R16_IBM))))
+           bswap_array (dest, dest, size / 2, nelems * 2);
+         else
+           bswap_array (dest, dest, size, nelems);
+       }
 
       if ((convert & GFC_CONVERT_R16_IEEE)
          && kind == 16
@@ -1274,6 +1291,18 @@ unformatted_write (st_parameter_dt *dtp, bt type,
          size /= 2;
        }
 
+#if !defined(HAVE_GFC_REAL_17) && defined(HAVE_GFC_REAL_16) \
+    && GFC_REAL_16_DIGITS == 106
+      /* IBM extended format is stored as a pair of IEEE754
+        double values, with the more significant value first
+        in both big and little endian.  */
+      if (kind == 16 && (type == BT_REAL || type == BT_COMPLEX))
+       {
+         nelems *= 2;
+         size /= 2;
+       }
+#endif
+
       /* By now, all complex variables have been split into their
         constituent reals.  */
 
@@ -1321,7 +1350,12 @@ unformatted_write (st_parameter_dt *dtp, bt type,
              if ((dtp->u.p.current_unit->flags.convert
                   & ~(GFC_CONVERT_R16_IEEE | GFC_CONVERT_R16_IBM))
                  == GFC_CONVERT_SWAP)
-               bswap_array (buffer, buffer, size, nc);
+               bswap_array (buffer, buffer, size / 2, nc * 2);
+           }
+         else if (kind == 16 && (type == BT_REAL || type == BT_COMPLEX))
+           {
+             bswap_array (buffer, p, size / 2, nc * 2);
+             p += size * nc;
            }
          else
 #endif