Imported gcc-4.4.3

[msp430-gcc.git] / libgcc / config / libbid / bid128_logb.c

diff --git a/libgcc/config/libbid/bid128_logb.c b/libgcc/config/libbid/bid128_logb.c
new file mode 100644 (file)
index 0000000..f462cf6
--- /dev/null
+++ b/libgcc/config/libbid/bid128_logb.c
@@ -0,0 +1,58 @@
+/* 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/>.  */
+
+#define BID_128RES
+#include "bid_internal.h"
+
+BID128_FUNCTION_ARG1_NORND_CUSTOMRESTYPE(int, bid128_logb, x)
+
+  UINT128 CX;
+  UINT64 sign_x;
+  SINT64 D;
+  int_float f64, fx;
+  int exponent_x, bin_expon_cx, digits;
+
+  if (!unpack_BID128_value (&sign_x, &exponent_x, &CX, x)) {
+#ifdef SET_STATUS_FLAGS
+      __set_status_flags (pfpsf, INVALID_EXCEPTION);
+#endif
+    BID_RETURN_VAL (0x80000000);
+  }
+  // find number of digits in coefficient
+  // 2^64
+  f64.i = 0x5f800000;
+  // fx ~ CX
+  fx.d = (float) CX.w[1] * f64.d + (float) CX.w[0];
+  bin_expon_cx = ((fx.i >> 23) & 0xff) - 0x7f;
+  digits = estimate_decimal_digits[bin_expon_cx];
+  // scale = 38-estimate_decimal_digits[bin_expon_cx];
+  D = CX.w[1] - power10_index_binexp_128[bin_expon_cx].w[1];
+  if (D > 0 || (!D && CX.w[0] >= power10_index_binexp_128[bin_expon_cx].w[0])) {
+    digits++;
+  }
+
+  exponent_x = exponent_x - DECIMAL_EXPONENT_BIAS_128 - 1 + digits;
+
+  BID_RETURN_VAL (exponent_x);
+
+}