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![Simon Arlott](/assets/img/avatar_default.png)
Spelling fixes in arch/parisc/. Signed-off-by: Simon Arlott <simon@fire.lp0.eu> Acked-by: Grant Grundler <grundler@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
195 lines
5.4 KiB
C
195 lines
5.4 KiB
C
/*
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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/dfsqrt.c $Revision: 1.1 $
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*
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* Purpose:
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* Double Floating-point Square Root
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*
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* External Interfaces:
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* dbl_fsqrt(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 "dbl_float.h"
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/*
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* Double Floating-point Square Root
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*/
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/*ARGSUSED*/
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unsigned int
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dbl_fsqrt(
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dbl_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 srcp1, srcp2, resultp1, resultp2;
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register unsigned int newbitp1, newbitp2, sump1, sump2;
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register int src_exponent;
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register boolean guardbit = FALSE, even_exponent;
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Dbl_copyfromptr(srcptr,srcp1,srcp2);
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/*
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* check source operand for NaN or infinity
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*/
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if ((src_exponent = Dbl_exponent(srcp1)) == DBL_INFINITY_EXPONENT) {
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/*
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* is signaling NaN?
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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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/* make NaN quiet */
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Set_invalidflag();
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Dbl_set_quiet(srcp1);
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}
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/*
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* Return quiet NaN or positive infinity.
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* Fall through to negative test if negative infinity.
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*/
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if (Dbl_iszero_sign(srcp1) ||
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Dbl_isnotzero_mantissa(srcp1,srcp2)) {
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Dbl_copytoptr(srcp1,srcp2,dstptr);
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return(NOEXCEPTION);
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}
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}
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/*
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* check for zero source operand
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*/
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if (Dbl_iszero_exponentmantissa(srcp1,srcp2)) {
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Dbl_copytoptr(srcp1,srcp2,dstptr);
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return(NOEXCEPTION);
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}
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/*
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* check for negative source operand
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*/
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if (Dbl_isone_sign(srcp1)) {
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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_makequietnan(srcp1,srcp2);
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Dbl_copytoptr(srcp1,srcp2,dstptr);
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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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if (src_exponent > 0) {
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even_exponent = Dbl_hidden(srcp1);
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Dbl_clear_signexponent_set_hidden(srcp1);
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}
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else {
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/* normalize operand */
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Dbl_clear_signexponent(srcp1);
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src_exponent++;
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Dbl_normalize(srcp1,srcp2,src_exponent);
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even_exponent = src_exponent & 1;
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}
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if (even_exponent) {
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/* exponent is even */
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/* Add comment here. Explain why odd exponent needs correction */
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Dbl_leftshiftby1(srcp1,srcp2);
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}
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/*
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* Add comment here. Explain following algorithm.
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*
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* Trust me, it works.
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*
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*/
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Dbl_setzero(resultp1,resultp2);
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Dbl_allp1(newbitp1) = 1 << (DBL_P - 32);
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Dbl_setzero_mantissap2(newbitp2);
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while (Dbl_isnotzero(newbitp1,newbitp2) && Dbl_isnotzero(srcp1,srcp2)) {
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Dbl_addition(resultp1,resultp2,newbitp1,newbitp2,sump1,sump2);
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if(Dbl_isnotgreaterthan(sump1,sump2,srcp1,srcp2)) {
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Dbl_leftshiftby1(newbitp1,newbitp2);
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/* update result */
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Dbl_addition(resultp1,resultp2,newbitp1,newbitp2,
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resultp1,resultp2);
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Dbl_subtract(srcp1,srcp2,sump1,sump2,srcp1,srcp2);
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Dbl_rightshiftby2(newbitp1,newbitp2);
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}
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else {
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Dbl_rightshiftby1(newbitp1,newbitp2);
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}
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Dbl_leftshiftby1(srcp1,srcp2);
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}
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/* correct exponent for pre-shift */
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if (even_exponent) {
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Dbl_rightshiftby1(resultp1,resultp2);
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}
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/* check for inexact */
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if (Dbl_isnotzero(srcp1,srcp2)) {
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if (!even_exponent && Dbl_islessthan(resultp1,resultp2,srcp1,srcp2)) {
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Dbl_increment(resultp1,resultp2);
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}
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guardbit = Dbl_lowmantissap2(resultp2);
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Dbl_rightshiftby1(resultp1,resultp2);
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/* now round result */
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switch (Rounding_mode()) {
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case ROUNDPLUS:
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Dbl_increment(resultp1,resultp2);
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break;
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case ROUNDNEAREST:
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/* stickybit is always true, so guardbit
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* is enough to determine rounding */
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if (guardbit) {
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Dbl_increment(resultp1,resultp2);
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}
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break;
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}
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/* increment result exponent by 1 if mantissa overflowed */
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if (Dbl_isone_hiddenoverflow(resultp1)) src_exponent+=2;
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if (Is_inexacttrap_enabled()) {
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Dbl_set_exponent(resultp1,
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((src_exponent-DBL_BIAS)>>1)+DBL_BIAS);
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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return(INEXACTEXCEPTION);
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}
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else Set_inexactflag();
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}
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else {
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Dbl_rightshiftby1(resultp1,resultp2);
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}
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Dbl_set_exponent(resultp1,((src_exponent-DBL_BIAS)>>1)+DBL_BIAS);
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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return(NOEXCEPTION);
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}
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