413 lines
11 KiB
C
413 lines
11 KiB
C
/* $NetBSD: dfdiv.c,v 1.4 2007/02/22 05:46:29 thorpej Exp $ */
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/* $OpenBSD: dfdiv.c,v 1.4 2001/03/29 03:58:17 mickey Exp $ */
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/*
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* Copyright 1996 1995 by Open Software Foundation, Inc.
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* All Rights Reserved
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*
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* Permission to use, copy, modify, and distribute this software and
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* its documentation for any purpose and without fee is hereby granted,
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* provided that the above copyright notice appears in all copies and
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* that both the copyright notice and this permission notice appear in
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* supporting documentation.
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*
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* OSF DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
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* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE.
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*
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* IN NO EVENT SHALL OSF BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
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* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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* LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
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* NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
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* WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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*/
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/*
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* pmk1.1
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*/
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/*
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* (c) Copyright 1986 HEWLETT-PACKARD COMPANY
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*
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* To anyone who acknowledges that this file is provided "AS IS"
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* without any express or implied warranty:
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* permission to use, copy, modify, and distribute this file
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* for any purpose is hereby granted without fee, provided that
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* the above copyright notice and this notice appears in all
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* copies, and that the name of Hewlett-Packard Company not be
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* used in advertising or publicity pertaining to distribution
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* of the software without specific, written prior permission.
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* Hewlett-Packard Company makes no representations about the
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* suitability of this software for any purpose.
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: dfdiv.c,v 1.4 2007/02/22 05:46:29 thorpej Exp $");
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#include "../spmath/float.h"
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#include "../spmath/dbl_float.h"
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/*
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* Double Precision Floating-point Divide
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*/
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int
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dbl_fdiv(srcptr1,srcptr2,dstptr,status)
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dbl_floating_point *srcptr1, *srcptr2, *dstptr;
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unsigned int *status;
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{
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register unsigned int opnd1p1, opnd1p2, opnd2p1, opnd2p2;
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register unsigned int opnd3p1, opnd3p2, resultp1, resultp2;
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register int dest_exponent, count;
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register int inexact = false, guardbit = false, stickybit = false;
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int is_tiny;
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Dbl_copyfromptr(srcptr1,opnd1p1,opnd1p2);
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Dbl_copyfromptr(srcptr2,opnd2p1,opnd2p2);
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/*
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* set sign bit of result
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*/
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if (Dbl_sign(opnd1p1) ^ Dbl_sign(opnd2p1))
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Dbl_setnegativezerop1(resultp1);
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else Dbl_setzerop1(resultp1);
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/*
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* check first operand for NaN's or infinity
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*/
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if (Dbl_isinfinity_exponent(opnd1p1)) {
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if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) {
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if (Dbl_isnotnan(opnd2p1,opnd2p2)) {
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if (Dbl_isinfinity(opnd2p1,opnd2p2)) {
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/*
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* invalid since both operands
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* are infinity
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*/
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if (Is_invalidtrap_enabled())
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return(INVALIDEXCEPTION);
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Set_invalidflag();
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Dbl_makequietnan(resultp1,resultp2);
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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return(NOEXCEPTION);
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}
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/*
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* return infinity
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*/
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Dbl_setinfinity_exponentmantissa(resultp1,resultp2);
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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return(NOEXCEPTION);
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}
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}
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else {
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/*
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* is NaN; signaling or quiet?
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*/
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if (Dbl_isone_signaling(opnd1p1)) {
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/* trap if INVALIDTRAP enabled */
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if (Is_invalidtrap_enabled())
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return(INVALIDEXCEPTION);
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/* make NaN quiet */
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Set_invalidflag();
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Dbl_set_quiet(opnd1p1);
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}
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/*
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* is second operand a signaling NaN?
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*/
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else if (Dbl_is_signalingnan(opnd2p1)) {
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/* trap if INVALIDTRAP enabled */
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if (Is_invalidtrap_enabled())
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return(INVALIDEXCEPTION);
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/* make NaN quiet */
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Set_invalidflag();
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Dbl_set_quiet(opnd2p1);
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Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
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return(NOEXCEPTION);
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}
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/*
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* return quiet NaN
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*/
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Dbl_copytoptr(opnd1p1,opnd1p2,dstptr);
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return(NOEXCEPTION);
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}
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}
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/*
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* check second operand for NaN's or infinity
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*/
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if (Dbl_isinfinity_exponent(opnd2p1)) {
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if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) {
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/*
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* return zero
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*/
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Dbl_setzero_exponentmantissa(resultp1,resultp2);
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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return(NOEXCEPTION);
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}
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/*
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* is NaN; signaling or quiet?
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*/
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if (Dbl_isone_signaling(opnd2p1)) {
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/* trap if INVALIDTRAP enabled */
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if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
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/* make NaN quiet */
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Set_invalidflag();
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Dbl_set_quiet(opnd2p1);
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}
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/*
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* return quiet NaN
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*/
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Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
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return(NOEXCEPTION);
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}
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/*
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* check for division by zero
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*/
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if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) {
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if (Dbl_iszero_exponentmantissa(opnd1p1,opnd1p2)) {
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/* invalid since both operands are zero */
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if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
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Set_invalidflag();
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Dbl_makequietnan(resultp1,resultp2);
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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return(NOEXCEPTION);
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}
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if (Is_divisionbyzerotrap_enabled())
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return(DIVISIONBYZEROEXCEPTION);
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Set_divisionbyzeroflag();
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Dbl_setinfinity_exponentmantissa(resultp1,resultp2);
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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return(NOEXCEPTION);
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}
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/*
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* Generate exponent
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*/
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dest_exponent = Dbl_exponent(opnd1p1) - Dbl_exponent(opnd2p1) + DBL_BIAS;
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/*
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* Generate mantissa
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*/
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if (Dbl_isnotzero_exponent(opnd1p1)) {
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/* set hidden bit */
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Dbl_clear_signexponent_set_hidden(opnd1p1);
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}
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else {
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/* check for zero */
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if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) {
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Dbl_setzero_exponentmantissa(resultp1,resultp2);
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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return(NOEXCEPTION);
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}
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/* is denormalized, want to normalize */
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Dbl_clear_signexponent(opnd1p1);
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Dbl_leftshiftby1(opnd1p1,opnd1p2);
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Dbl_normalize(opnd1p1,opnd1p2,dest_exponent);
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}
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/* opnd2 needs to have hidden bit set with msb in hidden bit */
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if (Dbl_isnotzero_exponent(opnd2p1)) {
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Dbl_clear_signexponent_set_hidden(opnd2p1);
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}
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else {
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/* is denormalized; want to normalize */
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Dbl_clear_signexponent(opnd2p1);
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Dbl_leftshiftby1(opnd2p1,opnd2p2);
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while (Dbl_iszero_hiddenhigh7mantissa(opnd2p1)) {
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dest_exponent+=8;
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Dbl_leftshiftby8(opnd2p1,opnd2p2);
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}
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if (Dbl_iszero_hiddenhigh3mantissa(opnd2p1)) {
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dest_exponent+=4;
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Dbl_leftshiftby4(opnd2p1,opnd2p2);
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}
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while (Dbl_iszero_hidden(opnd2p1)) {
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dest_exponent++;
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Dbl_leftshiftby1(opnd2p1,opnd2p2);
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}
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}
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/* Divide the source mantissas */
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/*
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* A non-restoring divide algorithm is used.
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*/
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Twoword_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2);
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Dbl_setzero(opnd3p1,opnd3p2);
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for (count=1; count <= DBL_P && (opnd1p1 || opnd1p2); count++) {
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Dbl_leftshiftby1(opnd1p1,opnd1p2);
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Dbl_leftshiftby1(opnd3p1,opnd3p2);
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if (Dbl_iszero_sign(opnd1p1)) {
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Dbl_setone_lowmantissap2(opnd3p2);
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Twoword_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2);
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}
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else {
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Twoword_add(opnd1p1, opnd1p2, opnd2p1, opnd2p2);
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}
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}
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if (count <= DBL_P) {
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Dbl_leftshiftby1(opnd3p1,opnd3p2);
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Dbl_setone_lowmantissap2(opnd3p2);
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Dbl_leftshift(opnd3p1,opnd3p2,(DBL_P-count));
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if (Dbl_iszero_hidden(opnd3p1)) {
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Dbl_leftshiftby1(opnd3p1,opnd3p2);
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dest_exponent--;
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}
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}
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else {
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if (Dbl_iszero_hidden(opnd3p1)) {
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/* need to get one more bit of result */
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Dbl_leftshiftby1(opnd1p1,opnd1p2);
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Dbl_leftshiftby1(opnd3p1,opnd3p2);
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if (Dbl_iszero_sign(opnd1p1)) {
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Dbl_setone_lowmantissap2(opnd3p2);
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Twoword_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2);
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}
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else {
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Twoword_add(opnd1p1,opnd1p2,opnd2p1,opnd2p2);
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}
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dest_exponent--;
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}
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if (Dbl_iszero_sign(opnd1p1)) guardbit = true;
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stickybit = Dbl_allp1(opnd1p1) || Dbl_allp2(opnd1p2);
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}
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inexact = guardbit | stickybit;
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/*
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* round result
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*/
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if (inexact && (dest_exponent > 0 || Is_underflowtrap_enabled())) {
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Dbl_clear_signexponent(opnd3p1);
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switch (Rounding_mode()) {
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case ROUNDPLUS:
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if (Dbl_iszero_sign(resultp1))
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Dbl_increment(opnd3p1,opnd3p2);
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break;
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case ROUNDMINUS:
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if (Dbl_isone_sign(resultp1))
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Dbl_increment(opnd3p1,opnd3p2);
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break;
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case ROUNDNEAREST:
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if (guardbit && (stickybit ||
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Dbl_isone_lowmantissap2(opnd3p2))) {
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Dbl_increment(opnd3p1,opnd3p2);
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}
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}
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if (Dbl_isone_hidden(opnd3p1)) dest_exponent++;
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}
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Dbl_set_mantissa(resultp1,resultp2,opnd3p1,opnd3p2);
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/*
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* Test for overflow
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*/
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if (dest_exponent >= DBL_INFINITY_EXPONENT) {
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/* trap if OVERFLOWTRAP enabled */
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if (Is_overflowtrap_enabled()) {
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/*
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* Adjust bias of result
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*/
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Dbl_setwrapped_exponent(resultp1,dest_exponent,ovfl);
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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if (inexact) {
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if (Is_inexacttrap_enabled())
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return(OVERFLOWEXCEPTION | INEXACTEXCEPTION);
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else
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Set_inexactflag();
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}
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return(OVERFLOWEXCEPTION);
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}
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Set_overflowflag();
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/* set result to infinity or largest number */
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Dbl_setoverflow(resultp1,resultp2);
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inexact = true;
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}
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/*
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* Test for underflow
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*/
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else if (dest_exponent <= 0) {
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/* trap if UNDERFLOWTRAP enabled */
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if (Is_underflowtrap_enabled()) {
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/*
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* Adjust bias of result
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*/
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Dbl_setwrapped_exponent(resultp1,dest_exponent,unfl);
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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if (inexact) {
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if (Is_inexacttrap_enabled())
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return(UNDERFLOWEXCEPTION | INEXACTEXCEPTION);
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else
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Set_inexactflag();
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}
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return(UNDERFLOWEXCEPTION);
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}
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/* Determine if should set underflow flag */
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is_tiny = true;
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if (dest_exponent == 0 && inexact) {
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switch (Rounding_mode()) {
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case ROUNDPLUS:
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if (Dbl_iszero_sign(resultp1)) {
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Dbl_increment(opnd3p1,opnd3p2);
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if (Dbl_isone_hiddenoverflow(opnd3p1))
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is_tiny = false;
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Dbl_decrement(opnd3p1,opnd3p2);
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}
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break;
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case ROUNDMINUS:
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if (Dbl_isone_sign(resultp1)) {
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Dbl_increment(opnd3p1,opnd3p2);
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if (Dbl_isone_hiddenoverflow(opnd3p1))
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is_tiny = false;
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Dbl_decrement(opnd3p1,opnd3p2);
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}
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break;
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case ROUNDNEAREST:
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if (guardbit && (stickybit ||
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Dbl_isone_lowmantissap2(opnd3p2))) {
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Dbl_increment(opnd3p1,opnd3p2);
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if (Dbl_isone_hiddenoverflow(opnd3p1))
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is_tiny = false;
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Dbl_decrement(opnd3p1,opnd3p2);
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}
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break;
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}
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}
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/*
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* denormalize result or set to signed zero
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*/
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stickybit = inexact;
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Dbl_denormalize(opnd3p1,opnd3p2,dest_exponent,guardbit,
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stickybit,inexact);
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/* return rounded number */
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if (inexact) {
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switch (Rounding_mode()) {
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case ROUNDPLUS:
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if (Dbl_iszero_sign(resultp1)) {
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Dbl_increment(opnd3p1,opnd3p2);
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}
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break;
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case ROUNDMINUS:
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if (Dbl_isone_sign(resultp1)) {
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Dbl_increment(opnd3p1,opnd3p2);
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}
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break;
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case ROUNDNEAREST:
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if (guardbit && (stickybit ||
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Dbl_isone_lowmantissap2(opnd3p2))) {
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Dbl_increment(opnd3p1,opnd3p2);
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}
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break;
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}
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if (is_tiny)
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Set_underflowflag();
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}
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Dbl_set_exponentmantissa(resultp1,resultp2,opnd3p1,opnd3p2);
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}
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else Dbl_set_exponent(resultp1,dest_exponent);
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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/* check for inexact */
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if (inexact) {
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if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
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else Set_inexactflag();
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}
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return(NOEXCEPTION);
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}
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