Add RISC-V port for libm

  Contributor list:
    - Michael Neilly  <mneilly@yahoo.com>
    - Kito Cheng  <kito.cheng@gmail.com>

1 files changed, 89 insertions, 0 deletions

diff --git a/newlib/libm/machine/riscv/feupdateenv.c b/newlib/libm/machine/riscv/feupdateenv.c
new file mode 100644
index 000000000..737095c2b
--- /dev/null
+++ b/newlib/libm/machine/riscv/feupdateenv.c
@@ -0,0 +1,89 @@
+/*
+  (c) Copyright 2017 Michael R. Neilly
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions
+  are met:
+
+  * Redistributions of source code must retain the above copyright
+  notice, this list of conditions and the following disclaimer.
+
+  * Redistributions in binary form must reproduce the above copyright
+  notice, this list of conditions and the following disclaimer in the
+  documentation and/or other materials provided with the distribution.
+
+  * Neither the names of the copyright holders nor the names of their
+  contributors may be used to endorse or promote products derived from
+  this software without specific prior written permission.
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+  COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+  ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+  POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include <fenv.h>
+
+/* This implementation is intended to comply with the following
+ * specification:
+ *
+ * http://pubs.opengroup.org/onlinepubs/9699919799/functions/feupdateenv.html
+ *
+ * "The feupdateenv() function shall attempt to save the currently
+ * raised floating-point exceptions in its automatic storage, attempt
+ * to install the floating-point environment represented by the object
+ * pointed to by envp, and then attempt to raise the saved
+ * floating-point exceptions. The argument envp shall point to an
+ * object set by a call to feholdexcept() or fegetenv(), or equal a
+ * floating-point environment macro."
+ */
+
+int feupdateenv(const fenv_t *envp)
+{
+
+#if __riscv_flen
+
+  /* Get current exception flags */
+
+  fexcept_t flags;
+  asm volatile("frflags %0" : "=r"(flags));
+
+  /* Set the environment as requested */
+
+  fenv_t fcsr = *envp; /* Environment to install */
+  asm volatile("fscsr %0" : : "r"(fcsr)); /* Install environment */
+
+  /* OR in the saved exception flags */
+
+  asm volatile("csrs fflags, %0" : : "r"(flags));
+
+  /* "The feupdateenv() function shall return a zero value if and only
+   * if all the required actions were successfully carried out."
+   */
+
+  return 0;
+
+#else
+
+  /* For soft float */
+
+#if defined FE_NOMASK_ENV && FE_ALL_EXCEPT != 0
+
+  if (envp == FE_NOMASK_ENV)
+      return 1;
+
+#endif
+
+  return 0;
+
+#endif
+}