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diff --git a/libgcc/config/libbid/bid64_logb.c b/libgcc/config/libbid/bid64_logb.c
new file mode 100644
index 00000000..eeb3fac2
--- /dev/null
+++ b/libgcc/config/libbid/bid64_logb.c
@@ -0,0 +1,68 @@
+/* Copyright (C) 2007, 2009  Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC 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 General Public License
+for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+<http://www.gnu.org/licenses/>.  */
+
+#include "bid_internal.h"
+
+#define MAX_FORMAT_DIGITS     16
+#define DECIMAL_EXPONENT_BIAS 398
+
+#if DECIMAL_CALL_BY_REFERENCE
+
+void
+bid64_logb (int * pres, UINT64 * px
+	    _EXC_FLAGS_PARAM _EXC_MASKS_PARAM _EXC_INFO_PARAM) {
+  UINT64 x;
+#else
+
+int
+bid64_logb (UINT64 x _EXC_FLAGS_PARAM _EXC_MASKS_PARAM _EXC_INFO_PARAM) {
+#endif
+  UINT64 sign_x, coefficient_x;
+  int_double dx;
+  int exponent_x, bin_expon_cx, digits;
+
+#if DECIMAL_CALL_BY_REFERENCE
+  x = *px;
+#endif
+  // unpack arguments, check for NaN or Infinity
+  if (!unpack_BID64 (&sign_x, &exponent_x, &coefficient_x, x)) {
+    // x is Inf. or NaN
+#ifdef SET_STATUS_FLAGS
+      __set_status_flags (pfpsf, INVALID_EXCEPTION);
+#endif
+      BID_RETURN (0x80000000);
+  }
+  // find number of digits in coefficient
+  if (coefficient_x >= 1000000000000000ull) {
+    digits = 16;
+  } else {
+    dx.d = (double)coefficient_x;   // exact conversion;
+    bin_expon_cx = (int)(dx.i >> 52) - 1023;
+    digits = estimate_decimal_digits[bin_expon_cx];
+    if (coefficient_x >= power10_table_128[digits].w[0])
+      digits++;
+  }
+  exponent_x = exponent_x - DECIMAL_EXPONENT_BIAS + digits - 1;
+
+  BID_RETURN (exponent_x);
+}