m68k: properly implement logbl for Motorola extended float

diff --git a/ChangeLog.m68k b/ChangeLog.m68k
index 393f3978dfded0b6eb9530cf69c9ed47b44ffb5e..a6f187120073c07c9a193cbafc148735fae2a68b 100644 (file)
--- a/ChangeLog.m68k
+++ b/ChangeLog.m68k
@@ -1,5 +1,7 @@
 2012-05-21  Andreas Schwab  <schwab@linux-m68k.org>
 
+       * sysdeps/m68k/m680x0/fpu/s_logbl.c: New file.
+
        * sysdeps/unix/sysv/linux/m68k/m680x0/nptl/libc.abilist: Update.
        * sysdeps/unix/sysv/linux/m68k/coldfire/nptl/libc.abilist: Update.
 

diff --git a/sysdeps/m68k/m680x0/fpu/s_logbl.c b/sysdeps/m68k/m680x0/fpu/s_logbl.c
new file mode 100644 (file)
index 0000000..2586622
--- /dev/null
+++ b/sysdeps/m68k/m680x0/fpu/s_logbl.c
@@ -0,0 +1,49 @@
+/* s_logbl.c -- long double version of s_logb.c.
+ * Conversion to long double by Ulrich Drepper,
+ * Cygnus Support, drepper@cygnus.com.
+ */
+
+/*
+ * ====================================================
+ * 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 <math.h>
+#include <math_private.h>
+
+long double
+__logbl (long double x)
+{
+  int32_t es, lx, ix;
+
+  GET_LDOUBLE_WORDS (es, ix, lx, x);
+  es &= 0x7fff;                        /* exponent */
+  if ((es | ix | lx) == 0)
+    return -1.0 / fabsl (x);
+  if (es == 0x7fff)
+    return x * x;
+  if (es == 0)                 /* IEEE 754 logb */
+    {
+      /* POSIX specifies that denormal number is treated as
+         though it were normalized.  */
+      if (ix == 0)
+       es = -(__builtin_clz (lx) + 32);
+      else
+       es = -__builtin_clz (ix);
+    }
+  return (long double) (es - 16383);
+}
+
+weak_alias (__logbl, logbl)