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/* $OpenBSD: dfmpy.c,v 1.3 1998/07/02 19:05:01 mickey Exp $ */
/*
* Copyright 1996 1995 by Open Software Foundation, Inc.
* All Rights Reserved
*
* Permission to use, copy, modify, and distribute this software and
* its documentation for any purpose and without fee is hereby granted,
* provided that the above copyright notice appears in all copies and
* that both the copyright notice and this permission notice appear in
* supporting documentation.
*
* OSF DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE.
*
* IN NO EVENT SHALL OSF BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
* NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
/*
* pmk1.1
*/
/*
* (c) Copyright 1986 HEWLETT-PACKARD COMPANY
*
* To anyone who acknowledges that this file is provided "AS IS"
* without any express or implied warranty:
* permission to use, copy, modify, and distribute this file
* for any purpose is hereby granted without fee, provided that
* the above copyright notice and this notice appears in all
* copies, and that the name of Hewlett-Packard Company not be
* used in advertising or publicity pertaining to distribution
* of the software without specific, written prior permission.
* Hewlett-Packard Company makes no representations about the
* suitability of this software for any purpose.
*/
#include "../spmath/float.h"
#include "../spmath/dbl_float.h"
/*
* Double Precision Floating-point Multiply
*/
int
dbl_fmpy(srcptr1,srcptr2,dstptr,status)
dbl_floating_point *srcptr1, *srcptr2, *dstptr;
unsigned int *status;
{
register unsigned int opnd1p1, opnd1p2, opnd2p1, opnd2p2;
register unsigned int opnd3p1, opnd3p2, resultp1, resultp2;
register int dest_exponent, count;
register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE;
boolean is_tiny;
Dbl_copyfromptr(srcptr1,opnd1p1,opnd1p2);
Dbl_copyfromptr(srcptr2,opnd2p1,opnd2p2);
/*
* set sign bit of result
*/
if (Dbl_sign(opnd1p1) ^ Dbl_sign(opnd2p1))
Dbl_setnegativezerop1(resultp1);
else Dbl_setzerop1(resultp1);
/*
* check first operand for NaN's or infinity
*/
if (Dbl_isinfinity_exponent(opnd1p1)) {
if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) {
if (Dbl_isnotnan(opnd2p1,opnd2p2)) {
if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) {
/*
* invalid since operands are infinity
* and zero
*/
if (Is_invalidtrap_enabled())
return(INVALIDEXCEPTION);
Set_invalidflag();
Dbl_makequietnan(resultp1,resultp2);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
/*
* return infinity
*/
Dbl_setinfinity_exponentmantissa(resultp1,resultp2);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
}
else {
/*
* is NaN; signaling or quiet?
*/
if (Dbl_isone_signaling(opnd1p1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Dbl_set_quiet(opnd1p1);
}
/*
* is second operand a signaling NaN?
*/
else if (Dbl_is_signalingnan(opnd2p1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Dbl_set_quiet(opnd2p1);
Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
return(NOEXCEPTION);
}
/*
* return quiet NaN
*/
Dbl_copytoptr(opnd1p1,opnd1p2,dstptr);
return(NOEXCEPTION);
}
}
/*
* check second operand for NaN's or infinity
*/
if (Dbl_isinfinity_exponent(opnd2p1)) {
if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) {
if (Dbl_iszero_exponentmantissa(opnd1p1,opnd1p2)) {
/* invalid since operands are zero & infinity */
if (Is_invalidtrap_enabled())
return(INVALIDEXCEPTION);
Set_invalidflag();
Dbl_makequietnan(opnd2p1,opnd2p2);
Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
return(NOEXCEPTION);
}
/*
* return infinity
*/
Dbl_setinfinity_exponentmantissa(resultp1,resultp2);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
/*
* is NaN; signaling or quiet?
*/
if (Dbl_isone_signaling(opnd2p1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Dbl_set_quiet(opnd2p1);
}
/*
* return quiet NaN
*/
Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
return(NOEXCEPTION);
}
/*
* Generate exponent
*/
dest_exponent = Dbl_exponent(opnd1p1) + Dbl_exponent(opnd2p1) -DBL_BIAS;
/*
* Generate mantissa
*/
if (Dbl_isnotzero_exponent(opnd1p1)) {
/* set hidden bit */
Dbl_clear_signexponent_set_hidden(opnd1p1);
}
else {
/* check for zero */
if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) {
Dbl_setzero_exponentmantissa(resultp1,resultp2);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
/* is denormalized, adjust exponent */
Dbl_clear_signexponent(opnd1p1);
Dbl_leftshiftby1(opnd1p1,opnd1p2);
Dbl_normalize(opnd1p1,opnd1p2,dest_exponent);
}
/* opnd2 needs to have hidden bit set with msb in hidden bit */
if (Dbl_isnotzero_exponent(opnd2p1)) {
Dbl_clear_signexponent_set_hidden(opnd2p1);
}
else {
/* check for zero */
if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) {
Dbl_setzero_exponentmantissa(resultp1,resultp2);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
/* is denormalized; want to normalize */
Dbl_clear_signexponent(opnd2p1);
Dbl_leftshiftby1(opnd2p1,opnd2p2);
Dbl_normalize(opnd2p1,opnd2p2,dest_exponent);
}
/* Multiply two source mantissas together */
/* make room for guard bits */
Dbl_leftshiftby7(opnd2p1,opnd2p2);
Dbl_setzero(opnd3p1,opnd3p2);
/*
* Four bits at a time are inspected in each loop, and a
* simple shift and add multiply algorithm is used.
*/
for (count=1;count<=DBL_P;count+=4) {
stickybit |= Dlow4p2(opnd3p2);
Dbl_rightshiftby4(opnd3p1,opnd3p2);
if (Dbit28p2(opnd1p2)) {
/* Twoword_add should be an ADDC followed by an ADD. */
Twoword_add(opnd3p1, opnd3p2, opnd2p1<<3 | opnd2p2>>29,
opnd2p2<<3);
}
if (Dbit29p2(opnd1p2)) {
Twoword_add(opnd3p1, opnd3p2, opnd2p1<<2 | opnd2p2>>30,
opnd2p2<<2);
}
if (Dbit30p2(opnd1p2)) {
Twoword_add(opnd3p1, opnd3p2, opnd2p1<<1 | opnd2p2>>31,
opnd2p2<<1);
}
if (Dbit31p2(opnd1p2)) {
Twoword_add(opnd3p1, opnd3p2, opnd2p1, opnd2p2);
}
Dbl_rightshiftby4(opnd1p1,opnd1p2);
}
if (Dbit3p1(opnd3p1)==0) {
Dbl_leftshiftby1(opnd3p1,opnd3p2);
}
else {
/* result mantissa >= 2. */
dest_exponent++;
}
/* check for denormalized result */
while (Dbit3p1(opnd3p1)==0) {
Dbl_leftshiftby1(opnd3p1,opnd3p2);
dest_exponent--;
}
/*
* check for guard, sticky and inexact bits
*/
stickybit |= Dallp2(opnd3p2) << 25;
guardbit = (Dallp2(opnd3p2) << 24) >> 31;
inexact = guardbit | stickybit;
/* align result mantissa */
Dbl_rightshiftby8(opnd3p1,opnd3p2);
/*
* round result
*/
if (inexact && (dest_exponent>0 || Is_underflowtrap_enabled())) {
Dbl_clear_signexponent(opnd3p1);
switch (Rounding_mode()) {
case ROUNDPLUS:
if (Dbl_iszero_sign(resultp1))
Dbl_increment(opnd3p1,opnd3p2);
break;
case ROUNDMINUS:
if (Dbl_isone_sign(resultp1))
Dbl_increment(opnd3p1,opnd3p2);
break;
case ROUNDNEAREST:
if (guardbit) {
if (stickybit || Dbl_isone_lowmantissap2(opnd3p2))
Dbl_increment(opnd3p1,opnd3p2);
}
}
if (Dbl_isone_hidden(opnd3p1)) dest_exponent++;
}
Dbl_set_mantissa(resultp1,resultp2,opnd3p1,opnd3p2);
/*
* Test for overflow
*/
if (dest_exponent >= DBL_INFINITY_EXPONENT) {
/* trap if OVERFLOWTRAP enabled */
if (Is_overflowtrap_enabled()) {
/*
* Adjust bias of result
*/
Dbl_setwrapped_exponent(resultp1,dest_exponent,ovfl);
Dbl_copytoptr(resultp1,resultp2,dstptr);
if (inexact) {
if (Is_inexacttrap_enabled())
return (OVERFLOWEXCEPTION | INEXACTEXCEPTION);
else
Set_inexactflag();
}
return (OVERFLOWEXCEPTION);
}
inexact = TRUE;
Set_overflowflag();
/* set result to infinity or largest number */
Dbl_setoverflow(resultp1,resultp2);
}
/*
* Test for underflow
*/
else if (dest_exponent <= 0) {
/* trap if UNDERFLOWTRAP enabled */
if (Is_underflowtrap_enabled()) {
/*
* Adjust bias of result
*/
Dbl_setwrapped_exponent(resultp1,dest_exponent,unfl);
Dbl_copytoptr(resultp1,resultp2,dstptr);
if (inexact) {
if (Is_inexacttrap_enabled())
return (UNDERFLOWEXCEPTION | INEXACTEXCEPTION);
else
Set_inexactflag();
}
return (UNDERFLOWEXCEPTION);
}
/* Determine if should set underflow flag */
is_tiny = TRUE;
if (dest_exponent == 0 && inexact) {
switch (Rounding_mode()) {
case ROUNDPLUS:
if (Dbl_iszero_sign(resultp1)) {
Dbl_increment(opnd3p1,opnd3p2);
if (Dbl_isone_hiddenoverflow(opnd3p1))
is_tiny = FALSE;
Dbl_decrement(opnd3p1,opnd3p2);
}
break;
case ROUNDMINUS:
if (Dbl_isone_sign(resultp1)) {
Dbl_increment(opnd3p1,opnd3p2);
if (Dbl_isone_hiddenoverflow(opnd3p1))
is_tiny = FALSE;
Dbl_decrement(opnd3p1,opnd3p2);
}
break;
case ROUNDNEAREST:
if (guardbit && (stickybit ||
Dbl_isone_lowmantissap2(opnd3p2))) {
Dbl_increment(opnd3p1,opnd3p2);
if (Dbl_isone_hiddenoverflow(opnd3p1))
is_tiny = FALSE;
Dbl_decrement(opnd3p1,opnd3p2);
}
break;
}
}
/*
* denormalize result or set to signed zero
*/
stickybit = inexact;
Dbl_denormalize(opnd3p1,opnd3p2,dest_exponent,guardbit,
stickybit,inexact);
/* return zero or smallest number */
if (inexact) {
switch (Rounding_mode()) {
case ROUNDPLUS:
if (Dbl_iszero_sign(resultp1)) {
Dbl_increment(opnd3p1,opnd3p2);
}
break;
case ROUNDMINUS:
if (Dbl_isone_sign(resultp1)) {
Dbl_increment(opnd3p1,opnd3p2);
}
break;
case ROUNDNEAREST:
if (guardbit && (stickybit ||
Dbl_isone_lowmantissap2(opnd3p2))) {
Dbl_increment(opnd3p1,opnd3p2);
}
break;
}
if (is_tiny) Set_underflowflag();
}
Dbl_set_exponentmantissa(resultp1,resultp2,opnd3p1,opnd3p2);
}
else Dbl_set_exponent(resultp1,dest_exponent);
/* check for inexact */
Dbl_copytoptr(resultp1,resultp2,dstptr);
if (inexact) {
if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
else Set_inexactflag();
}
return(NOEXCEPTION);
}
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