1 files changed, 41 insertions, 0 deletions
diff --git a/sysdeps/i386/fpu/s_f32xsubf64.c b/sysdeps/i386/fpu/s_f32xsubf64.c
new file mode 100644
index 0000000..3a7dbca
--- /dev/null
+++ b/sysdeps/i386/fpu/s_f32xsubf64.c
@@ -0,0 +1,41 @@
+/* Subtract _Float64 values, converting the result to _Float32x.  i386 version.
+   Copyright (C) 2018 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.
+
+   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 <math.h>
+#include <fpu_control.h>
+#include <math_private.h>
+#include <math-narrow.h>
+
+_Float32x
+__f32xsubf64 (_Float64 x, _Float64 y)
+{
+  /* To avoid double rounding, set double precision for the subtraction.
+     math_narrow_eval is still needed to eliminate excess range in the
+     case of overflow.  If the result of the subtraction is in the
+     subnormal range for double, it is exact, so no issues of double
+     rounding for subnormals arise.  */
+  fpu_control_t cw, cw_double;
+  _FPU_GETCW (cw);
+  cw_double = (cw & ~_FPU_EXTENDED) | _FPU_DOUBLE;
+  _FPU_SETCW (cw_double);
+  _Float32x ret = math_narrow_eval (x - y);
+  _FPU_SETCW (cw);
+  CHECK_NARROW_SUB (ret, x, y);
+  return ret;
+}
+libm_alias_float32x_float64 (sub)