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[/] [openrisc/] [trunk/] [gnu-src/] [gcc-4.5.1/] [libgcc/] [config/] [libbid/] [bid128_logb.c] - Rev 280
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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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