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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
commit554fd8c5195424bdbcabf5de30fdc183aba391bd (patch)
tree976dc5ab7fddf506dadce60ae936f43f58787092 /libgcc/config/libbid/bid128_logb.c
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Diffstat (limited to 'libgcc/config/libbid/bid128_logb.c')
-rw-r--r--libgcc/config/libbid/bid128_logb.c58
1 files changed, 58 insertions, 0 deletions
diff --git a/libgcc/config/libbid/bid128_logb.c b/libgcc/config/libbid/bid128_logb.c
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+++ b/libgcc/config/libbid/bid128_logb.c
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+/* 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);
+
+}