1 files changed, 47 insertions, 0 deletions
diff --git a/libquadmath/math/logbq.c b/libquadmath/math/logbq.c
new file mode 100644
index 00000000000..2e47a4b434a
--- /dev/null
+++ b/libquadmath/math/logbq.c
@@ -0,0 +1,47 @@
+/* s_logbl.c -- long double version of s_logb.c.
+ * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
+ */
+
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+/*
+ * long double logbl(x)
+ * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
+ * Use ilogb instead.
+ */
+
+#include "quadmath-imp.h"
+
+__float128
+logbq (__float128 x)
+{
+  int64_t lx, hx, ex;
+
+  GET_FLT128_WORDS64 (hx, lx, x);
+  hx &= 0x7fffffffffffffffLL;	/* high |x| */
+  if ((hx | lx) == 0)
+    return -1.0 / fabsq (x);
+  if (hx >= 0x7fff000000000000LL)
+    return x * x;
+  if ((ex = hx >> 48) == 0)	/* IEEE 754 logb */
+    {
+      /* POSIX specifies that denormal number is treated as
+         though it were normalized.  */
+      int ma;
+      if (hx == 0)
+	ma = __builtin_clzll (lx) + 64;
+      else
+	ma = __builtin_clzll (hx);
+      ex -= ma - 16;
+    }
+  return (__float128) (ex - 16383);
+}