301 lines
8.2 KiB
C
301 lines
8.2 KiB
C
/* $NetBSD: dfrem.c,v 1.1 2002/06/05 01:04:24 fredette Exp $ */
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/* $OpenBSD: dfrem.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 "../spmath/float.h"
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#include "../spmath/dbl_float.h"
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/*
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* Double Precision Floating-point Remainder
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*/
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int
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dbl_frem(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 resultp1, resultp2;
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register int opnd1_exponent, opnd2_exponent, dest_exponent, stepcount;
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register int roundup = FALSE;
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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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* check first operand for NaN's or infinity
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*/
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if ((opnd1_exponent = Dbl_exponent(opnd1p1)) == DBL_INFINITY_EXPONENT) {
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if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) {
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if (Dbl_isnotnan(opnd2p1,opnd2p2)) {
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/* invalid since first operand is infinity */
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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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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 ((opnd2_exponent = Dbl_exponent(opnd2p1)) == DBL_INFINITY_EXPONENT) {
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if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) {
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/*
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* return first operand
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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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* 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 second operand for zero
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*/
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if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) {
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/* invalid since second operand is 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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/*
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* get sign of result
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*/
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resultp1 = opnd1p1;
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/*
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* check for denormalized operands
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*/
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if (opnd1_exponent == 0) {
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/* check for zero */
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if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) {
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Dbl_copytoptr(opnd1p1,opnd1p2,dstptr);
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return(NOEXCEPTION);
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}
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/* normalize, then continue */
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opnd1_exponent = 1;
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Dbl_normalize(opnd1p1,opnd1p2,opnd1_exponent);
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}
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else {
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Dbl_clear_signexponent_set_hidden(opnd1p1);
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}
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if (opnd2_exponent == 0) {
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/* normalize, then continue */
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opnd2_exponent = 1;
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Dbl_normalize(opnd2p1,opnd2p2,opnd2_exponent);
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}
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else {
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Dbl_clear_signexponent_set_hidden(opnd2p1);
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}
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/* find result exponent and divide step loop count */
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dest_exponent = opnd2_exponent - 1;
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stepcount = opnd1_exponent - opnd2_exponent;
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/*
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* check for opnd1/opnd2 < 1
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*/
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if (stepcount < 0) {
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/*
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* check for opnd1/opnd2 > 1/2
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*
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* In this case n will round to 1, so
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* r = opnd1 - opnd2
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*/
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if (stepcount == -1 &&
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Dbl_isgreaterthan(opnd1p1,opnd1p2,opnd2p1,opnd2p2)) {
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/* set sign */
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Dbl_allp1(resultp1) = ~Dbl_allp1(resultp1);
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/* align opnd2 with opnd1 */
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Dbl_leftshiftby1(opnd2p1,opnd2p2);
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Dbl_subtract(opnd2p1,opnd2p2,opnd1p1,opnd1p2,
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opnd2p1,opnd2p2);
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/* now normalize */
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while (Dbl_iszero_hidden(opnd2p1)) {
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Dbl_leftshiftby1(opnd2p1,opnd2p2);
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dest_exponent--;
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}
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Dbl_set_exponentmantissa(resultp1,resultp2,opnd2p1,opnd2p2);
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goto testforunderflow;
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}
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/*
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* opnd1/opnd2 <= 1/2
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*
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* In this case n will round to zero, so
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* r = opnd1
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*/
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Dbl_set_exponentmantissa(resultp1,resultp2,opnd1p1,opnd1p2);
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dest_exponent = opnd1_exponent;
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goto testforunderflow;
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}
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/*
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* Generate result
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*
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* Do iterative subtract until remainder is less than operand 2.
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*/
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while (stepcount-- > 0 && (Dbl_allp1(opnd1p1) || Dbl_allp2(opnd1p2))) {
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if (Dbl_isnotlessthan(opnd1p1,opnd1p2,opnd2p1,opnd2p2)) {
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Dbl_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2,opnd1p1,opnd1p2);
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}
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Dbl_leftshiftby1(opnd1p1,opnd1p2);
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}
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/*
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* Do last subtract, then determine which way to round if remainder
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* is exactly 1/2 of opnd2
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*/
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if (Dbl_isnotlessthan(opnd1p1,opnd1p2,opnd2p1,opnd2p2)) {
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Dbl_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2,opnd1p1,opnd1p2);
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roundup = TRUE;
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}
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if (stepcount > 0 || Dbl_iszero(opnd1p1,opnd1p2)) {
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/* division is exact, remainder is zero */
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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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* Check for cases where opnd1/opnd2 < n
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*
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* In this case the result's sign will be opposite that of
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* opnd1. The mantissa also needs some correction.
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*/
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Dbl_leftshiftby1(opnd1p1,opnd1p2);
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if (Dbl_isgreaterthan(opnd1p1,opnd1p2,opnd2p1,opnd2p2)) {
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Dbl_invert_sign(resultp1);
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Dbl_leftshiftby1(opnd2p1,opnd2p2);
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Dbl_subtract(opnd2p1,opnd2p2,opnd1p1,opnd1p2,opnd1p1,opnd1p2);
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}
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/* check for remainder being exactly 1/2 of opnd2 */
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else if (Dbl_isequal(opnd1p1,opnd1p2,opnd2p1,opnd2p2) && roundup) {
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Dbl_invert_sign(resultp1);
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}
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/* normalize result's mantissa */
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while (Dbl_iszero_hidden(opnd1p1)) {
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dest_exponent--;
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Dbl_leftshiftby1(opnd1p1,opnd1p2);
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}
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Dbl_set_exponentmantissa(resultp1,resultp2,opnd1p1,opnd1p2);
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/*
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* Test for underflow
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*/
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testforunderflow:
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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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/* frem is always exact */
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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return(UNDERFLOWEXCEPTION);
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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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if (dest_exponent >= (1 - DBL_P)) {
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Dbl_rightshift_exponentmantissa(resultp1,resultp2,
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1-dest_exponent);
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}
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else {
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Dbl_setzero_exponentmantissa(resultp1,resultp2);
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}
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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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return(NOEXCEPTION);
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}
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