1 files changed, 75 insertions, 0 deletions
diff --git a/libgcc/soft-fp/truncbfhf2.c b/libgcc/soft-fp/truncbfhf2.c
new file mode 100644
index 0000000..6b6e6b4
--- /dev/null
+++ b/libgcc/soft-fp/truncbfhf2.c
@@ -0,0 +1,75 @@
+/* Software floating-point emulation.
+   Truncate bfloat16 into IEEE half.
+   Copyright (C) 2022 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 "brain.h"
+#include "single.h"
+
+/* BFtype and HFtype are unordered, neither is a superset or subset
+   of each other.  Convert BFtype to SFtype (lossless) and then
+   truncate to HFtype.  */
+
+HFtype
+__truncbfhf2 (BFtype a)
+{
+  FP_DECL_EX;
+  FP_DECL_H (A);
+  FP_DECL_S (B);
+  FP_DECL_B (R);
+  SFtype b;
+  HFtype r;
+
+  FP_INIT_ROUNDMODE;
+  /* Optimize BFtype to SFtype conversion to simple left shift
+     by 16 if possible, we don't need to raise exceptions on sNaN
+     here as the SFtype to HFtype truncation should do that too.  */
+  if (sizeof (BFtype) == 2
+      && sizeof (unsigned short) == 2
+      && sizeof (SFtype) == 4
+      && sizeof (unsigned int) == 4)
+    {
+      union { BFtype a; unsigned short b; } u1;
+      union { SFtype a; unsigned int b; } u2;
+      u1.a = a;
+      u2.b = (u1.b << 8) << 8;
+      b = u2.a;
+    }
+  else
+    {
+      FP_UNPACK_RAW_B (A, a);
+      FP_EXTEND (S, B, 1, 1, B, A);
+      FP_PACK_RAW_S (b, B);
+    }
+  FP_UNPACK_SEMIRAW_S (B, b);
+  FP_TRUNC (H, S, 1, 1, R, B);
+  FP_PACK_SEMIRAW_H (r, R);
+  FP_HANDLE_EXCEPTIONS;
+
+  return r;
+}