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[/] [openrisc/] [trunk/] [gnu-src/] [gcc-4.5.1/] [libgcc/] [config/] [libbid/] [bid64_scalb.c] - Rev 300
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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/>. */ #include "bid_internal.h" #define MAX_FORMAT_DIGITS 16 #define DECIMAL_EXPONENT_BIAS 398 #define MAX_DECIMAL_EXPONENT 767 #if DECIMAL_CALL_BY_REFERENCE void bid64_scalb (UINT64 * pres, UINT64 * px, int *pn _RND_MODE_PARAM _EXC_FLAGS_PARAM _EXC_MASKS_PARAM _EXC_INFO_PARAM) { UINT64 x; int n; #else UINT64 bid64_scalb (UINT64 x, int n _RND_MODE_PARAM _EXC_FLAGS_PARAM _EXC_MASKS_PARAM _EXC_INFO_PARAM) { #endif UINT64 sign_x, coefficient_x, res; SINT64 exp64; int exponent_x, rmode; #if DECIMAL_CALL_BY_REFERENCE #if !DECIMAL_GLOBAL_ROUNDING _IDEC_round rnd_mode = *prnd_mode; #endif x = *px; n = *pn; #endif // unpack arguments, check for NaN or Infinity if (!unpack_BID64 (&sign_x, &exponent_x, &coefficient_x, x)) { // x is Inf. or NaN or 0 #ifdef SET_STATUS_FLAGS if ((x & SNAN_MASK64) == SNAN_MASK64) // y is sNaN __set_status_flags (pfpsf, INVALID_EXCEPTION); #endif if (coefficient_x) res = coefficient_x & QUIET_MASK64; else { exp64 = (SINT64) exponent_x + (SINT64) n; if(exp64<0) exp64=0; if(exp64>MAX_DECIMAL_EXPONENT) exp64=MAX_DECIMAL_EXPONENT; exponent_x = exp64; res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x); // 0 } BID_RETURN (res); } exp64 = (SINT64) exponent_x + (SINT64) n; exponent_x = exp64; if ((UINT32) exponent_x <= MAX_DECIMAL_EXPONENT) { res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x); BID_RETURN (res); } // check for overflow if (exp64 > MAX_DECIMAL_EXPONENT) { // try to normalize coefficient while ((coefficient_x < 1000000000000000ull) && (exp64 > MAX_DECIMAL_EXPONENT)) { // coefficient_x < 10^15, scale by 10 coefficient_x = (coefficient_x << 1) + (coefficient_x << 3); exponent_x--; exp64--; } if (exp64 <= MAX_DECIMAL_EXPONENT) { res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x); BID_RETURN (res); } else exponent_x = 0x7fffffff; // overflow } // exponent < 0 // the BID pack routine will round the coefficient rmode = rnd_mode; res = get_BID64 (sign_x, exponent_x, coefficient_x, rmode, pfpsf); BID_RETURN (res); }
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