2002-05-28 Roland McGrath <roland@frob.com>

	* sysdeps/mach/alpha/setfpucw.c: New file.

diff --git a/sysdeps/mach/alpha/setfpucw.c b/sysdeps/mach/alpha/setfpucw.c
new file mode 100644 (file)
index 0000000..a2887c8
--- /dev/null
+++ b/sysdeps/mach/alpha/setfpucw.c
@@ -0,0 +1,69 @@
+/* Set FP exception mask and rounding mode.  Mach/Alpha version.
+   Copyright (C) 2002 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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <fpu_control.h>
+
+
+#define FPCR_DYN_SHIFT 58              /* first dynamic rounding mode bit */
+#define FPCR_DYN_CHOPPED (0x0UL << FPCR_DYN_SHIFT)     /* towards 0 */
+#define FPCR_DYN_MINUS  (0x1UL << FPCR_DYN_SHIFT)      /* towards -INF */
+#define FPCR_DYN_NORMAL         (0x2UL << FPCR_DYN_SHIFT)      /* towards nearest */
+#define FPCR_DYN_PLUS   (0x3UL << FPCR_DYN_SHIFT)      /* towards +INF */
+#define FPCR_DYN_MASK   (0x3UL << FPCR_DYN_SHIFT)
+
+static inline unsigned long
+rdfpcr (void)
+{
+  unsigned long fpcr;
+  asm ("excb; mf_fpcr %0" : "=f"(fpcr));
+  return fpcr;
+}
+
+static inline void
+wrfpcr (unsigned long fpcr)
+{
+  asm volatile ("mt_fpcr %0; excb" : : "f"(fpcr));
+}
+
+
+void
+__setfpucw (fpu_control_t fpu_control)
+{
+  unsigned long fpcr;
+
+  if (!fpu_control)
+    fpu_control = _FPU_DEFAULT;
+
+  /* first, set dynamic rounding mode: */
+
+  fpcr = rdfpcr();
+  fpcr &= ~FPCR_DYN_MASK;
+  switch (fpu_control & 0xc00)
+    {
+    case _FPU_RC_NEAREST:      fpcr |= FPCR_DYN_NORMAL; break;
+    case _FPU_RC_DOWN:         fpcr |= FPCR_DYN_MINUS; break;
+    case _FPU_RC_UP:           fpcr |= FPCR_DYN_PLUS; break;
+    case _FPU_RC_ZERO:         fpcr |= FPCR_DYN_CHOPPED; break;
+    }
+  wrfpcr(fpcr);
+
+  /* XXX trap bits? */
+
+  __fpu_control = fpu_control; /* update global copy */
+}