OpenSolaris_b135/lib/libbc/libc/gen/common/pack_float.c
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 1988-1995, by Sun Microsystems, Inc.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
#include "base_conversion.h"
void
_fp_rightshift(pu, n)
unpacked *pu;
int n;
/* Right shift significand sticky by n bits. */
{
int i;
if (n >= (32 * UNPACKED_SIZE)) { /* drastic */
for (i = 0; (pu->significand[i] == 0) && (i < UNPACKED_SIZE); i++);
if (i >= UNPACKED_SIZE) {
pu->fpclass = fp_zero;
return;
} else {
for (i = 0; i < (UNPACKED_SIZE - 1); i++)
pu->significand[i] = 0;
pu->significand[UNPACKED_SIZE - 1] = 1;
return;
}
}
while (n >= 32) { /* big shift */
if (pu->significand[UNPACKED_SIZE - 1] != 0)
pu->significand[UNPACKED_SIZE - 2] |= 1;
for (i = UNPACKED_SIZE - 2; i >= 0; i--)
pu->significand[i + 1] = pu->significand[i];
pu->significand[0] = 0;
n -= 32;
}
if (n >= 1) { /* small shift */
unsigned long high, low, shiftout = 0;
for (i = 0; i < UNPACKED_SIZE; i++) {
high = pu->significand[i] >> n;
low = pu->significand[i] << (32 - n);
pu->significand[i] = shiftout | high;
shiftout = low;
}
if (shiftout != 0)
pu->significand[UNPACKED_SIZE - 1] |= 1;
}
}
PRIVATE int
overflow_to_infinity(sign)
int sign;
/* Returns 1 if overflow should go to infinity, 0 if to max finite. */
{
int inf;
switch (_fp_current_direction) {
case fp_nearest:
inf = 1;
break;
case fp_tozero:
inf = 0;
break;
case fp_positive:
inf = !sign;
break;
case fp_negative:
inf = sign;
break;
}
return (inf);
}
PRIVATE void
round(pu, roundword)
unpacked *pu;
/*
* Round according to current rounding mode. pu must be shifted to so that
* the roundbit is pu->significand[roundword] & 0x80000000
*/
{
int increment; /* boolean to indicate round up */
int is;
unsigned msw; /* msw before increment */
for (is = (roundword + 1); is < UNPACKED_SIZE; is++)
if (pu->significand[is] != 0) { /* Condense extra bits into
* sticky bottom of
* roundword. */
pu->significand[roundword] |= 1;
break;
}
if (pu->significand[roundword] == 0)
return;
_fp_set_exception(fp_inexact);
switch (_fp_current_direction) {
case fp_nearest:
increment = pu->significand[roundword] >= 0x80000000;
break;
case fp_tozero:
increment = 0;
break;
case fp_positive:
increment = (pu->sign == 0) & (pu->significand[roundword] != 0);
break;
case fp_negative:
increment = (pu->sign != 0) & (pu->significand[roundword] != 0);
break;
}
if (increment) {
msw=pu->significand[0]; /* save msw before round */
is = roundword;
do {
is--;
pu->significand[is]++;
}
while ((pu->significand[is] == 0) && (is > 0));
if (pu->significand[0] < msw) { /* rounding carried out */
pu->exponent++;
pu->significand[0] = 0x80000000;
}
}
if ((_fp_current_direction == fp_nearest) && (pu->significand[roundword] == 0x80000000)) { /* ambiguous case */
pu->significand[roundword - 1] &= ~1; /* force round to even */
}
}
void
_pack_single(pu, px)
unpacked *pu; /* unpacked result */
single *px; /* packed single */
{
single_equivalence kluge;
kluge.f.msw.sign = pu->sign;
switch (pu->fpclass) {
case fp_zero:
kluge.f.msw.exponent = 0;
kluge.f.msw.significand = 0;
break;
case fp_infinity:
infinity:
kluge.f.msw.exponent = 0xff;
kluge.f.msw.significand = 0;
break;
case fp_quiet:
kluge.f.msw.exponent = 0xff;
kluge.f.msw.significand = 0x400000 | (0x3fffff & (pu->significand[0] >> 8));
break;
case fp_normal:
_fp_rightshift(pu, 8);
pu->exponent += SINGLE_BIAS;
if (pu->exponent <= 0) {
kluge.f.msw.exponent = 0;
_fp_rightshift(pu, 1 - pu->exponent);
round(pu, 1);
if (pu->significand[0] == 0x800000) { /* rounded back up to
* normal */
kluge.f.msw.exponent = 1;
kluge.f.msw.significand = 0;
_fp_set_exception(fp_underflow);
goto ret;
}
if (_fp_current_exceptions & (1 << fp_inexact))
_fp_set_exception(fp_underflow);
kluge.f.msw.significand = 0x7fffff & pu->significand[0];
goto ret;
}
round(pu, 1);
if (pu->significand[0] == 0x1000000) { /* rounding overflow */
pu->significand[0] = 0x800000;
pu->exponent += 1;
}
if (pu->exponent >= 0xff) {
_fp_set_exception(fp_overflow);
_fp_set_exception(fp_inexact);
if (overflow_to_infinity(pu->sign))
goto infinity;
kluge.f.msw.exponent = 0xfe;
kluge.f.msw.significand = 0x7fffff;
goto ret;
}
kluge.f.msw.exponent = pu->exponent;
kluge.f.msw.significand = 0x7fffff & pu->significand[0];
}
ret:
*px = kluge.x;
}
void
_pack_double(pu, px)
unpacked *pu; /* unpacked result */
double *px; /* packed double */
{
double_equivalence kluge;
kluge.f.msw.sign = pu->sign;
switch (pu->fpclass) {
case fp_zero:
kluge.f.msw.exponent = 0;
kluge.f.msw.significand = 0;
kluge.f.significand2 = 0;
break;
case fp_infinity:
infinity:
kluge.f.msw.exponent = 0x7ff;
kluge.f.msw.significand = 0;
kluge.f.significand2 = 0;
break;
case fp_quiet:
kluge.f.msw.exponent = 0x7ff;
_fp_rightshift(pu, 11);
kluge.f.msw.significand = 0x80000 | (0x7ffff & pu->significand[0]);
kluge.f.significand2 = pu->significand[1];
break;
case fp_normal:
_fp_rightshift(pu, 11);
pu->exponent += DOUBLE_BIAS;
if (pu->exponent <= 0) { /* underflow */
kluge.f.msw.exponent = 0;
_fp_rightshift(pu, 1 - pu->exponent);
round(pu, 2);
if (pu->significand[0] == 0x100000) { /* rounded back up to
* normal */
kluge.f.msw.exponent = 1;
kluge.f.msw.significand = 0;
kluge.f.significand2 = 0;
_fp_set_exception(fp_underflow);
goto ret;
}
if (_fp_current_exceptions & (1 << fp_inexact))
_fp_set_exception(fp_underflow);
kluge.f.msw.exponent = 0;
kluge.f.msw.significand = 0xfffff & pu->significand[0];
kluge.f.significand2 = pu->significand[1];
goto ret;
}
round(pu, 2);
if (pu->significand[0] == 0x200000) { /* rounding overflow */
pu->significand[0] = 0x100000;
pu->exponent += 1;
}
if (pu->exponent >= 0x7ff) { /* overflow */
_fp_set_exception(fp_overflow);
_fp_set_exception(fp_inexact);
if (overflow_to_infinity(pu->sign))
goto infinity;
kluge.f.msw.exponent = 0x7fe;
kluge.f.msw.significand = 0xfffff;
kluge.f.significand2 = 0xffffffff;
goto ret;
}
kluge.f.msw.exponent = pu->exponent;
kluge.f.msw.significand = 0xfffff & pu->significand[0];
kluge.f.significand2 = pu->significand[1];
break;
}
ret:
*px = kluge.x;
}
void
_pack_extended(pu, px)
unpacked *pu; /* unpacked result */
extended *px; /* packed extended */
{
extended_equivalence kluge;
kluge.f.msw.sign = pu->sign;
switch (pu->fpclass) {
case fp_zero:
kluge.f.msw.exponent = 0;
kluge.f.significand = 0;
kluge.f.significand2 = 0;
break;
case fp_infinity:
infinity:
kluge.f.msw.exponent = 0x7fff;
kluge.f.significand = 0;
kluge.f.significand2 = 0;
break;
case fp_quiet:
kluge.f.msw.exponent = 0x7fff;
kluge.f.significand = 0x40000000 | (0x7fffffff & pu->significand[0]);
kluge.f.significand2 = pu->significand[1];
break;
case fp_normal:
switch (_fp_current_precision) {
case fp_single:
{
single s;
_pack_single(pu, &s);
_unpack_single(pu, &s);
break;
}
case fp_double:
{
double s;
_pack_double(pu, &s);
_unpack_double(pu, &s);
break;
}
}
pu->exponent += EXTENDED_BIAS;
if (pu->exponent <= 0) { /* underflow */
kluge.f.msw.exponent = 0;
_fp_rightshift(pu, -pu->exponent);
round(pu, 2);
if (_fp_current_exceptions & (1 << fp_inexact))
_fp_set_exception(fp_underflow);
kluge.f.msw.exponent = 0;
kluge.f.significand = pu->significand[0];
kluge.f.significand2 = pu->significand[1];
goto ret;
}
round(pu, 2);
if (pu->exponent >= 0x7fff) { /* overflow */
_fp_set_exception(fp_overflow);
_fp_set_exception(fp_inexact);
if (overflow_to_infinity(pu->sign))
goto infinity;
kluge.f.msw.exponent = 0x7ffe;
kluge.f.significand = 0xffffffff;
kluge.f.significand2 = 0xffffffff;
goto ret;
}
kluge.f.msw.exponent = pu->exponent;
kluge.f.significand = pu->significand[0];
kluge.f.significand2 = pu->significand[1];
break;
}
ret:
(*px)[0] = kluge.x[0];
(*px)[1] = kluge.x[1];
(*px)[2] = kluge.x[2];
}
void
_pack_quadruple(pu, px)
unpacked *pu; /* unpacked result */
quadruple *px; /* packed quadruple */
{
quadruple_equivalence kluge;
int i;
kluge.f.msw.sign = pu->sign;
switch (pu->fpclass) {
case fp_zero:
kluge.f.msw.exponent = 0;
kluge.f.msw.significand = 0;
kluge.f.significand2 = 0;
kluge.f.significand3 = 0;
kluge.f.significand4 = 0;
break;
case fp_infinity:
infinity:
kluge.f.msw.exponent = 0x7fff;
kluge.f.msw.significand = 0;
kluge.f.significand2 = 0;
kluge.f.significand3 = 0;
kluge.f.significand4 = 0;
break;
case fp_quiet:
kluge.f.msw.exponent = 0x7fff;
_fp_rightshift(pu, 15);
kluge.f.msw.significand = 0x8000 | (0xffff & pu->significand[0]);
kluge.f.significand2 = pu->significand[1];
kluge.f.significand3 = pu->significand[2];
kluge.f.significand4 = pu->significand[3];
break;
case fp_normal:
_fp_rightshift(pu, 15);
pu->exponent += QUAD_BIAS;
if (pu->exponent <= 0) { /* underflow */
kluge.f.msw.exponent = 0;
_fp_rightshift(pu, 1 - pu->exponent);
round(pu, 4);
if (pu->significand[0] == 0x10000) { /* rounded back up to
* normal */
kluge.f.msw.exponent = 1;
kluge.f.msw.significand = 0;
kluge.f.significand2 = 0;
kluge.f.significand3 = 0;
kluge.f.significand4 = 0;
_fp_set_exception(fp_underflow);
goto ret;
}
if (_fp_current_exceptions & (1 << fp_inexact))
_fp_set_exception(fp_underflow);
kluge.f.msw.exponent = 0;
kluge.f.msw.significand = 0xffff & pu->significand[0];
kluge.f.significand2 = pu->significand[1];
kluge.f.significand3 = pu->significand[2];
kluge.f.significand4 = pu->significand[3];
goto ret;
}
round(pu, 4);
if (pu->significand[0] == 0x20000) { /* rounding overflow */
pu->significand[0] = 0x10000;
pu->exponent += 1;
}
if (pu->exponent >= 0x7fff) { /* overflow */
_fp_set_exception(fp_overflow);
_fp_set_exception(fp_inexact);
if (overflow_to_infinity(pu->sign))
goto infinity;
kluge.f.msw.exponent = 0x7ffe;
kluge.f.msw.significand = 0xffff;
kluge.f.significand2 = 0xffffffff;
kluge.f.significand3 = 0xffffffff;
kluge.f.significand4 = 0xffffffff;
goto ret;
}
kluge.f.msw.exponent = pu->exponent;
kluge.f.msw.significand = pu->significand[0] & 0xffff;
kluge.f.significand2 = pu->significand[1];
kluge.f.significand3 = pu->significand[2];
kluge.f.significand4 = pu->significand[3];
break;
}
ret:
#ifdef __STDC__
*px = kluge.x;
#else
for (i = 0; i < 4; i++)
px->u[i] = kluge.x.u[i];
#endif
}