soft-fp: Add __extendhfsf2/__extendhfdf2, __truncsfhf2/__truncdfhf2, __eqhf2/__nehf2

1. Add __extendhfdf2/__extendhfsf2 to return an IEEE half converted to IEEE double/single.
2. Add __truncdfhf2/__extendsfhf2 to truncate IEEE double/single into IEEE half.
3. Add __eqhf2/__nehf2 to return 0 if a == b and a,b are not NAN, otherwise return 1.

These are needed by x86 _Float16:

https://software.intel.com/content/www/us/en/develop/download/intel-avx512-fp16-architecture-specification.html

support in GCC.

1 files changed, 52 insertions, 0 deletions

diff --git a/soft-fp/truncdfhf2.c b/soft-fp/truncdfhf2.c
new file mode 100644
index 0000000000..8bcb278769
--- /dev/null
+++ b/soft-fp/truncdfhf2.c
@@ -0,0 +1,52 @@
+/* Software floating-point emulation.
+   Truncate IEEE double into IEEE half.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C 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 2.1 of the License, or (at your option) any later version.
+
+   In addition to the permissions in the GNU Lesser General Public
+   License, the Free Software Foundation gives you unlimited
+   permission to link the compiled version of this file into
+   combinations with other programs, and to distribute those
+   combinations without any restriction coming from the use of this
+   file.  (The Lesser General Public License restrictions do apply in
+   other respects; for example, they cover modification of the file,
+   and distribution when not linked into a combine executable.)
+
+   The GNU C 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 C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include "soft-fp.h"
+#include "half.h"
+#include "double.h"
+
+HFtype
+__truncdfhf2 (DFtype a)
+{
+  FP_DECL_EX;
+  FP_DECL_D (A);
+  FP_DECL_H (R);
+  HFtype r;
+
+  FP_INIT_ROUNDMODE;
+  FP_UNPACK_SEMIRAW_D (A, a);
+#if _FP_W_TYPE_SIZE < _FP_FRACBITS_D
+  FP_TRUNC (H, D, 1, 2, R, A);
+#else
+  FP_TRUNC (H, D, 1, 1, R, A);
+#endif
+  FP_PACK_SEMIRAW_H (r, R);
+  FP_HANDLE_EXCEPTIONS;
+
+  return r;
+}