310 строки
9.2 KiB
C
310 строки
9.2 KiB
C
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/*
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* Linux/PA-RISC Project (http://www.parisc-linux.org/)
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*
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* Floating-point emulation code
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* Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/*
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* BEGIN_DESC
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*
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* File:
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* @(#) pa/spmath/fcnvff.c $Revision: 1.1 $
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*
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* Purpose:
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* Single Floating-point to Double Floating-point
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* Double Floating-point to Single Floating-point
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*
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* External Interfaces:
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* dbl_to_sgl_fcnvff(srcptr,nullptr,dstptr,status)
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* sgl_to_dbl_fcnvff(srcptr,nullptr,dstptr,status)
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*
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* Internal Interfaces:
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*
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* Theory:
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* <<please update with a overview of the operation of this file>>
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*
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* END_DESC
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*/
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#include "float.h"
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#include "sgl_float.h"
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#include "dbl_float.h"
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#include "cnv_float.h"
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/*
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* Single Floating-point to Double Floating-point
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*/
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/*ARGSUSED*/
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int
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sgl_to_dbl_fcnvff(
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sgl_floating_point *srcptr,
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unsigned int *nullptr,
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dbl_floating_point *dstptr,
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unsigned int *status)
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{
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register unsigned int src, resultp1, resultp2;
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register int src_exponent;
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src = *srcptr;
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src_exponent = Sgl_exponent(src);
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Dbl_allp1(resultp1) = Sgl_all(src); /* set sign of result */
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/*
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* Test for NaN or infinity
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*/
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if (src_exponent == SGL_INFINITY_EXPONENT) {
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/*
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* determine if NaN or infinity
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*/
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if (Sgl_iszero_mantissa(src)) {
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/*
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* is infinity; want to return double 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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else {
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/*
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* is NaN; signaling or quiet?
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*/
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if (Sgl_isone_signaling(src)) {
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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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else {
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Set_invalidflag();
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Sgl_set_quiet(src);
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}
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}
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/*
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* NaN is quiet, return as double NaN
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*/
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Dbl_setinfinity_exponent(resultp1);
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Sgl_to_dbl_mantissa(src,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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/*
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* Test for zero or denormalized
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*/
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if (src_exponent == 0) {
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/*
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* determine if zero or denormalized
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*/
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if (Sgl_isnotzero_mantissa(src)) {
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/*
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* is denormalized; want to normalize
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*/
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Sgl_clear_signexponent(src);
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Sgl_leftshiftby1(src);
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Sgl_normalize(src,src_exponent);
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Sgl_to_dbl_exponent(src_exponent,resultp1);
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Sgl_to_dbl_mantissa(src,resultp1,resultp2);
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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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Dbl_copytoptr(resultp1,resultp2,dstptr);
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return(NOEXCEPTION);
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}
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/*
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* No special cases, just complete the conversion
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*/
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Sgl_to_dbl_exponent(src_exponent, resultp1);
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Sgl_to_dbl_mantissa(Sgl_mantissa(src), 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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* Double Floating-point to Single Floating-point
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*/
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/*ARGSUSED*/
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int
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dbl_to_sgl_fcnvff(
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dbl_floating_point *srcptr,
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unsigned int *nullptr,
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sgl_floating_point *dstptr,
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unsigned int *status)
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{
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register unsigned int srcp1, srcp2, result;
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register int src_exponent, dest_exponent, dest_mantissa;
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register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE;
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register boolean lsb_odd = FALSE;
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boolean is_tiny;
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Dbl_copyfromptr(srcptr,srcp1,srcp2);
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src_exponent = Dbl_exponent(srcp1);
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Sgl_all(result) = Dbl_allp1(srcp1); /* set sign of result */
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/*
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* Test for NaN or infinity
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*/
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if (src_exponent == DBL_INFINITY_EXPONENT) {
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/*
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* determine if NaN or infinity
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*/
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if (Dbl_iszero_mantissa(srcp1,srcp2)) {
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/*
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* is infinity; want to return single infinity
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*/
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Sgl_setinfinity_exponentmantissa(result);
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*dstptr = result;
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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(srcp1)) {
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/* trap if INVALIDTRAP enabled */
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if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
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else {
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Set_invalidflag();
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/* make NaN quiet */
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Dbl_set_quiet(srcp1);
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}
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}
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/*
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* NaN is quiet, return as single NaN
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*/
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Sgl_setinfinity_exponent(result);
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Sgl_set_mantissa(result,Dallp1(srcp1)<<3 | Dallp2(srcp2)>>29);
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if (Sgl_iszero_mantissa(result)) Sgl_set_quiet(result);
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*dstptr = result;
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return(NOEXCEPTION);
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}
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/*
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* Generate result
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*/
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Dbl_to_sgl_exponent(src_exponent,dest_exponent);
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if (dest_exponent > 0) {
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Dbl_to_sgl_mantissa(srcp1,srcp2,dest_mantissa,inexact,guardbit,
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stickybit,lsb_odd);
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}
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else {
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if (Dbl_iszero_exponentmantissa(srcp1,srcp2)){
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Sgl_setzero_exponentmantissa(result);
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*dstptr = result;
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return(NOEXCEPTION);
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}
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if (Is_underflowtrap_enabled()) {
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Dbl_to_sgl_mantissa(srcp1,srcp2,dest_mantissa,inexact,
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guardbit,stickybit,lsb_odd);
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}
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else {
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/* compute result, determine inexact info,
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* and set Underflowflag if appropriate
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*/
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Dbl_to_sgl_denormalized(srcp1,srcp2,dest_exponent,
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dest_mantissa,inexact,guardbit,stickybit,lsb_odd,
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is_tiny);
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}
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}
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/*
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* Now round result if not exact
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*/
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if (inexact) {
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switch (Rounding_mode()) {
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case ROUNDPLUS:
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if (Sgl_iszero_sign(result)) dest_mantissa++;
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break;
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case ROUNDMINUS:
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if (Sgl_isone_sign(result)) dest_mantissa++;
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break;
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case ROUNDNEAREST:
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if (guardbit) {
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if (stickybit || lsb_odd) dest_mantissa++;
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}
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}
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}
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Sgl_set_exponentmantissa(result,dest_mantissa);
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/*
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* check for mantissa overflow after rounding
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*/
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if ((dest_exponent>0 || Is_underflowtrap_enabled()) &&
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Sgl_isone_hidden(result)) dest_exponent++;
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/*
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* Test for overflow
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*/
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if (dest_exponent >= SGL_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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* Check for gross overflow
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*/
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if (dest_exponent >= SGL_INFINITY_EXPONENT+SGL_WRAP)
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return(UNIMPLEMENTEDEXCEPTION);
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/*
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* Adjust bias of result
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*/
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Sgl_setwrapped_exponent(result,dest_exponent,ovfl);
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*dstptr = result;
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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 Set_inexactflag();
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return(OVERFLOWEXCEPTION);
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}
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Set_overflowflag();
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inexact = TRUE;
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/* set result to infinity or largest number */
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Sgl_setoverflow(result);
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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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* Check for gross underflow
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*/
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if (dest_exponent <= -(SGL_WRAP))
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return(UNIMPLEMENTEDEXCEPTION);
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/*
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* Adjust bias of result
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*/
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Sgl_setwrapped_exponent(result,dest_exponent,unfl);
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*dstptr = result;
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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 Set_inexactflag();
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return(UNDERFLOWEXCEPTION);
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}
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/*
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* result is denormalized or signed zero
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*/
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if (inexact && is_tiny) Set_underflowflag();
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}
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else Sgl_set_exponent(result,dest_exponent);
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*dstptr = result;
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/*
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* Trap if inexact trap is enabled
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*/
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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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return(NOEXCEPTION);
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}
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