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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);
}
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