/*
* 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.
*/
/*
* Single Precision Floating-point Divide
*/
int
sgl_fdiv(sgl_floating_point *srcptr1, sgl_floating_point *srcptr2,
sgl_floating_point *dstptr, unsigned int *status)
{
register unsigned int opnd1, opnd2, opnd3, result;
register int dest_exponent, count;
register int inexact = false, guardbit = false, stickybit = false;
int is_tiny;
opnd1 = *srcptr1;
opnd2 = *srcptr2;
/*
* set sign bit of result
*/
if (Sgl_sign(opnd1) ^ Sgl_sign(opnd2)) Sgl_setnegativezero(result);
else Sgl_setzero(result);
/*
* check first operand for NaN's or infinity
*/
if (Sgl_isinfinity_exponent(opnd1)) {
if (Sgl_iszero_mantissa(opnd1)) {
if (Sgl_isnotnan(opnd2)) {
if (Sgl_isinfinity(opnd2)) {
/*
* invalid since both operands
* are infinity
*/
if (Is_invalidtrap_enabled())
return(INVALIDEXCEPTION);
Set_invalidflag();
Sgl_makequietnan(result);
*dstptr = result;
return(NOEXCEPTION);
}
/*
* return infinity
*/
Sgl_setinfinity_exponentmantissa(result);
*dstptr = result;
return(NOEXCEPTION);
}
}
else {
/*
* is NaN; signaling or quiet?
*/
if (Sgl_isone_signaling(opnd1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(opnd1);
}
/*
* is second operand a signaling NaN?
*/
else if (Sgl_is_signalingnan(opnd2)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(opnd2);
*dstptr = opnd2;
return(NOEXCEPTION);
}
/*
* return quiet NaN
*/
*dstptr = opnd1;
return(NOEXCEPTION);
}
}
/*
* check second operand for NaN's or infinity
*/
if (Sgl_isinfinity_exponent(opnd2)) {
if (Sgl_iszero_mantissa(opnd2)) {
/*
* return zero
*/
Sgl_setzero_exponentmantissa(result);
*dstptr = result;
return(NOEXCEPTION);
}
/*
* is NaN; signaling or quiet?
*/
if (Sgl_isone_signaling(opnd2)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(opnd2);
}
/*
* return quiet NaN
*/
*dstptr = opnd2;
return(NOEXCEPTION);
}
/*
* check for division by zero
*/
if (Sgl_iszero_exponentmantissa(opnd2)) {
if (Sgl_iszero_exponentmantissa(opnd1)) {
/* invalid since both operands are zero */
if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
Set_invalidflag();
Sgl_makequietnan(result);
*dstptr = result;
return(NOEXCEPTION);
}
if (Is_divisionbyzerotrap_enabled())
return(DIVISIONBYZEROEXCEPTION);
Set_divisionbyzeroflag();
Sgl_setinfinity_exponentmantissa(result);
*dstptr = result;
return(NOEXCEPTION);
}
/*
* Generate exponent
*/
dest_exponent = Sgl_exponent(opnd1) - Sgl_exponent(opnd2) + SGL_BIAS;
/*
* Generate mantissa
*/
if (Sgl_isnotzero_exponent(opnd1)) {
/* set hidden bit */
Sgl_clear_signexponent_set_hidden(opnd1);
}
else {
/* check for zero */
if (Sgl_iszero_mantissa(opnd1)) {
Sgl_setzero_exponentmantissa(result);
*dstptr = result;
return(NOEXCEPTION);
}
/* is denormalized; want to normalize */
Sgl_clear_signexponent(opnd1);
Sgl_leftshiftby1(opnd1);
Sgl_normalize(opnd1,dest_exponent);
}
/* opnd2 needs to have hidden bit set with msb in hidden bit */
if (Sgl_isnotzero_exponent(opnd2)) {
Sgl_clear_signexponent_set_hidden(opnd2);
}
else {
/* is denormalized; want to normalize */
Sgl_clear_signexponent(opnd2);
Sgl_leftshiftby1(opnd2);
while(Sgl_iszero_hiddenhigh7mantissa(opnd2)) {
Sgl_leftshiftby8(opnd2);
dest_exponent += 8;
}
if(Sgl_iszero_hiddenhigh3mantissa(opnd2)) {
Sgl_leftshiftby4(opnd2);
dest_exponent += 4;
}
while(Sgl_iszero_hidden(opnd2)) {
Sgl_leftshiftby1(opnd2);
dest_exponent += 1;
}
}
/* Divide the source mantissas */
/*
* A non_restoring divide algorithm is used.
*/
Sgl_subtract(opnd1,opnd2,opnd1);
Sgl_setzero(opnd3);
for (count=1;count<=SGL_P && Sgl_all(opnd1);count++) {
Sgl_leftshiftby1(opnd1);
Sgl_leftshiftby1(opnd3);
if (Sgl_iszero_sign(opnd1)) {
Sgl_setone_lowmantissa(opnd3);
Sgl_subtract(opnd1,opnd2,opnd1);
}
else Sgl_addition(opnd1,opnd2,opnd1);
}
if (count <= SGL_P) {
Sgl_leftshiftby1(opnd3);
Sgl_setone_lowmantissa(opnd3);
Sgl_leftshift(opnd3,SGL_P-count);
if (Sgl_iszero_hidden(opnd3)) {
Sgl_leftshiftby1(opnd3);
dest_exponent--;
}
}
else {
if (Sgl_iszero_hidden(opnd3)) {
/* need to get one more bit of result */
Sgl_leftshiftby1(opnd1);
Sgl_leftshiftby1(opnd3);
if (Sgl_iszero_sign(opnd1)) {
Sgl_setone_lowmantissa(opnd3);
Sgl_subtract(opnd1,opnd2,opnd1);
}
else Sgl_addition(opnd1,opnd2,opnd1);
dest_exponent--;
}
if (Sgl_iszero_sign(opnd1)) guardbit = true;
stickybit = Sgl_all(opnd1);
}
inexact = guardbit | stickybit;
/*
* round result
*/
if (inexact && (dest_exponent > 0 || Is_underflowtrap_enabled())) {
Sgl_clear_signexponent(opnd3);
switch (Rounding_mode()) {
case ROUNDPLUS:
if (Sgl_iszero_sign(result))
Sgl_increment_mantissa(opnd3);
break;
case ROUNDMINUS:
if (Sgl_isone_sign(result))
Sgl_increment_mantissa(opnd3);
break;
case ROUNDNEAREST:
if (guardbit &&
(stickybit || Sgl_isone_lowmantissa(opnd3)))
Sgl_increment_mantissa(opnd3);
}
if (Sgl_isone_hidden(opnd3)) dest_exponent++;
}
Sgl_set_mantissa(result,opnd3);
/*
* Test for overflow
*/
if (dest_exponent >= SGL_INFINITY_EXPONENT) {
/* trap if OVERFLOWTRAP enabled */
if (Is_overflowtrap_enabled()) {
/*
* Adjust bias of result
*/
Sgl_setwrapped_exponent(result,dest_exponent,ovfl);
*dstptr = result;
if (inexact) {
if (Is_inexacttrap_enabled())
return(OVERFLOWEXCEPTION | INEXACTEXCEPTION);
else Set_inexactflag();
}
return(OVERFLOWEXCEPTION);
}
Set_overflowflag();
/* set result to infinity or largest number */
Sgl_setoverflow(result);
inexact = true;
}
/*
* Test for underflow
*/
else if (dest_exponent <= 0) {
/* trap if UNDERFLOWTRAP enabled */
if (Is_underflowtrap_enabled()) {
/*
* Adjust bias of result
*/
Sgl_setwrapped_exponent(result,dest_exponent,unfl);
*dstptr = result;
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 (Sgl_iszero_sign(result)) {
Sgl_increment(opnd3);
if (Sgl_isone_hiddenoverflow(opnd3))
is_tiny = false;
Sgl_decrement(opnd3);
}
break;
case ROUNDMINUS:
if (Sgl_isone_sign(result)) {
Sgl_increment(opnd3);
if (Sgl_isone_hiddenoverflow(opnd3))
is_tiny = false;
Sgl_decrement(opnd3);
}
break;
case ROUNDNEAREST:
if (guardbit && (stickybit ||
Sgl_isone_lowmantissa(opnd3))) {
Sgl_increment(opnd3);
if (Sgl_isone_hiddenoverflow(opnd3))
is_tiny = false;
Sgl_decrement(opnd3);
}
break;
}
}
/*
* denormalize result or set to signed zero
*/
stickybit = inexact;
Sgl_denormalize(opnd3,dest_exponent,guardbit,stickybit,inexact);
/* return rounded number */
if (inexact) {
switch (Rounding_mode()) {
case ROUNDPLUS:
if (Sgl_iszero_sign(result)) {
Sgl_increment(opnd3);
}
break;
case ROUNDMINUS:
if (Sgl_isone_sign(result)) {
Sgl_increment(opnd3);
}
break;
case ROUNDNEAREST:
if (guardbit && (stickybit ||
Sgl_isone_lowmantissa(opnd3))) {
Sgl_increment(opnd3);
}
break;
}
if (is_tiny) Set_underflowflag();
}
Sgl_set_exponentmantissa(result,opnd3);
}
else Sgl_set_exponent(result,dest_exponent);
*dstptr = result;
/* check for inexact */
if (inexact) {
if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
else Set_inexactflag();
}
return(NOEXCEPTION);
}
