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/* IEEE754 floating point arithmetic
* double precision: common utilities
*/
/*
* MIPS floating point support
* Copyright (C) 1994-2000 Algorithmics Ltd.
* http://www.algor.co.uk
*
* ########################################################################
*
* This program is free software; you can distribute it and/or modify it
* under the terms of the GNU General Public License (Version 2) as
* published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
*
* ########################################################################
*/
#include "ieee754dp.h"
int ieee754dp_class(ieee754dp x)
{
COMPXDP;
EXPLODEXDP;
return xc;
}
int ieee754dp_isnan(ieee754dp x)
{
return ieee754dp_class(x) >= IEEE754_CLASS_SNAN;
}
int ieee754dp_issnan(ieee754dp x)
{
assert(ieee754dp_isnan(x));
return ((DPMANT(x) & DP_MBIT(DP_MBITS-1)) == DP_MBIT(DP_MBITS-1));
}
ieee754dp ieee754dp_xcpt(ieee754dp r, const char *op, ...)
{
struct ieee754xctx ax;
if (!TSTX())
return r;
ax.op = op;
ax.rt = IEEE754_RT_DP;
ax.rv.dp = r;
va_start(ax.ap, op);
ieee754_xcpt(&ax);
va_end(ax.ap);
return ax.rv.dp;
}
ieee754dp ieee754dp_nanxcpt(ieee754dp r, const char *op, ...)
{
struct ieee754xctx ax;
assert(ieee754dp_isnan(r));
if (!ieee754dp_issnan(r)) /* QNAN does not cause invalid op !! */
return r;
if (!SETANDTESTCX(IEEE754_INVALID_OPERATION)) {
/* not enabled convert to a quiet NaN */
DPMANT(r) &= (~DP_MBIT(DP_MBITS-1));
if (ieee754dp_isnan(r))
return r;
else
return ieee754dp_indef();
}
ax.op = op;
ax.rt = 0;
ax.rv.dp = r;
va_start(ax.ap, op);
ieee754_xcpt(&ax);
va_end(ax.ap);
return ax.rv.dp;
}
ieee754dp ieee754dp_bestnan(ieee754dp x, ieee754dp y)
{
assert(ieee754dp_isnan(x));
assert(ieee754dp_isnan(y));
if (DPMANT(x) > DPMANT(y))
return x;
else
return y;
}
static u64 get_rounding(int sn, u64 xm)
{
/* inexact must round of 3 bits
*/
if (xm & (DP_MBIT(3) - 1)) {
switch (ieee754_csr.rm) {
case IEEE754_RZ:
break;
case IEEE754_RN:
xm += 0x3 + ((xm >> 3) & 1);
/* xm += (xm&0x8)?0x4:0x3 */
break;
case IEEE754_RU: /* toward +Infinity */
if (!sn) /* ?? */
xm += 0x8;
break;
case IEEE754_RD: /* toward -Infinity */
if (sn) /* ?? */
xm += 0x8;
break;
}
}
return xm;
}
/* generate a normal/denormal number with over,under handling
* sn is sign
* xe is an unbiased exponent
* xm is 3bit extended precision value.
*/
ieee754dp ieee754dp_format(int sn, int xe, u64 xm)
{
assert(xm); /* we don't gen exact zeros (probably should) */
assert((xm >> (DP_MBITS + 1 + 3)) == 0); /* no execess */
assert(xm & (DP_HIDDEN_BIT << 3));
if (xe < DP_EMIN) {
/* strip lower bits */
int es = DP_EMIN - xe;
if (ieee754_csr.nod) {
SETCX(IEEE754_UNDERFLOW);
SETCX(IEEE754_INEXACT);
switch(ieee754_csr.rm) {
case IEEE754_RN:
return ieee754dp_zero(sn);
case IEEE754_RZ:
return ieee754dp_zero(sn);
case IEEE754_RU: /* toward +Infinity */
if(sn == 0)
return ieee754dp_min(0);
else
return ieee754dp_zero(1);
case IEEE754_RD: /* toward -Infinity */
if(sn == 0)
return ieee754dp_zero(0);
else
return ieee754dp_min(1);
}
}
if (xe == DP_EMIN - 1
&& get_rounding(sn, xm) >> (DP_MBITS + 1 + 3))
{
/* Not tiny after rounding */
SETCX(IEEE754_INEXACT);
xm = get_rounding(sn, xm);
xm >>= 1;
/* Clear grs bits */
xm &= ~(DP_MBIT(3) - 1);
xe++;
}
else {
/* sticky right shift es bits
*/
xm = XDPSRS(xm, es);
xe += es;
assert((xm & (DP_HIDDEN_BIT << 3)) == 0);
assert(xe == DP_EMIN);
}
}
if (xm & (DP_MBIT(3) - 1)) {
SETCX(IEEE754_INEXACT);
if ((xm & (DP_HIDDEN_BIT << 3)) == 0) {
SETCX(IEEE754_UNDERFLOW);
}
/* inexact must round of 3 bits
*/
xm = get_rounding(sn, xm);
/* adjust exponent for rounding add overflowing
*/
if (xm >> (DP_MBITS + 3 + 1)) {
/* add causes mantissa overflow */
xm >>= 1;
xe++;
}
}
/* strip grs bits */
xm >>= 3;
assert((xm >> (DP_MBITS + 1)) == 0); /* no execess */
assert(xe >= DP_EMIN);
if (xe > DP_EMAX) {
SETCX(IEEE754_OVERFLOW);
SETCX(IEEE754_INEXACT);
/* -O can be table indexed by (rm,sn) */
switch (ieee754_csr.rm) {
case IEEE754_RN:
return ieee754dp_inf(sn);
case IEEE754_RZ:
return ieee754dp_max(sn);
case IEEE754_RU: /* toward +Infinity */
if (sn == 0)
return ieee754dp_inf(0);
else
return ieee754dp_max(1);
case IEEE754_RD: /* toward -Infinity */
if (sn == 0)
return ieee754dp_max(0);
else
return ieee754dp_inf(1);
}
}
/* gen norm/denorm/zero */
if ((xm & DP_HIDDEN_BIT) == 0) {
/* we underflow (tiny/zero) */
assert(xe == DP_EMIN);
if (ieee754_csr.mx & IEEE754_UNDERFLOW)
SETCX(IEEE754_UNDERFLOW);
return builddp(sn, DP_EMIN - 1 + DP_EBIAS, xm);
} else {
assert((xm >> (DP_MBITS + 1)) == 0); /* no execess */
assert(xm & DP_HIDDEN_BIT);
return builddp(sn, xe + DP_EBIAS, xm & ~DP_HIDDEN_BIT);
}
}
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