1 files changed, 78 insertions, 0 deletions
diff --git a/newlib/libm/common/nexttowardf.c b/newlib/libm/common/nexttowardf.c
new file mode 100644
index 000000000..6f473190f
--- /dev/null
+++ b/newlib/libm/common/nexttowardf.c
@@ -0,0 +1,78 @@
+/*
+ * Copyright © 2005-2014 Rich Felker, et al.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <math.h>
+#include <inttypes.h>
+#include "local.h"
+
+union fshape {
+  float value;
+  uint32_t bits;
+};
+
+// This is only necessary because the implementation of isnan only works
+// properly when long double == double.
+// See: https://sourceware.org/ml/newlib/2014/msg00684.html
+#ifdef _LDBL_EQ_DOUBLE
+
+float
+nexttowardf (float x, long double y)
+{
+  union fshape ux;
+  uint32_t e;
+
+  if (isnan(x) || isnan(y))
+    return x + y;
+  if (x == y)
+    return y;
+  ux.value = x;
+  if (x == 0) {
+    ux.bits = 1;
+    if (signbit(y))
+      ux.bits |= 0x80000000;
+  } else if (x < y) {
+    if (signbit(x))
+      ux.bits--;
+    else
+      ux.bits++;
+  } else {
+    if (signbit(x))
+      ux.bits++;
+    else
+      ux.bits--;
+  }
+  e = ux.bits & 0x7f800000;
+  /* raise overflow if ux.value is infinite and x is finite */
+  if (e == 0x7f800000) {
+    volatile float force_eval;
+    force_eval = x + x;
+  }
+  /* raise underflow if ux.value is subnormal or zero */
+  if (e == 0) {
+    volatile float force_eval;
+    force_eval = x*x + ux.value*ux.value;
+  }
+  return ux.value;
+}
+
+#endif // _LDBL_EQ_DOUBLE