/*
* sgl_cmp: compare two values
*/
int
sgl_fcmp (sgl_floating_point * leftptr, sgl_floating_point * rightptr,
unsigned int cond, unsigned int *status)
/* The predicate to be tested */
{
register unsigned int left, right;
register int xorresult;
/* Create local copies of the numbers */
left = *leftptr;
right = *rightptr;
/*
* Test for NaN
*/
if( (Sgl_exponent(left) == SGL_INFINITY_EXPONENT)
|| (Sgl_exponent(right) == SGL_INFINITY_EXPONENT) )
{
/* Check if a NaN is involved. Signal an invalid exception when
* comparing a signaling NaN or when comparing quiet NaNs and the
* low bit of the condition is set */
if( ( (Sgl_exponent(left) == SGL_INFINITY_EXPONENT)
&& Sgl_isnotzero_mantissa(left)
&& (Exception(cond) || Sgl_isone_signaling(left)))
||
( (Sgl_exponent(right) == SGL_INFINITY_EXPONENT)
&& Sgl_isnotzero_mantissa(right)
&& (Exception(cond) || Sgl_isone_signaling(right)) ) )
{
if( Is_invalidtrap_enabled() ) {
Set_status_cbit(Unordered(cond));
return(INVALIDEXCEPTION);
}
else Set_invalidflag();
Set_status_cbit(Unordered(cond));
return(NOEXCEPTION);
}
/* All the exceptional conditions are handled, now special case
NaN compares */
else if( ((Sgl_exponent(left) == SGL_INFINITY_EXPONENT)
&& Sgl_isnotzero_mantissa(left))
||
((Sgl_exponent(right) == SGL_INFINITY_EXPONENT)
&& Sgl_isnotzero_mantissa(right)) )
{
/* NaNs always compare unordered. */
Set_status_cbit(Unordered(cond));
return(NOEXCEPTION);
}
/* infinities will drop down to the normal compare mechanisms */
}
/* First compare for unequal signs => less or greater or
* special equal case */
Sgl_xortointp1(left,right,xorresult);
if( xorresult < 0 )
{
/* left negative => less, left positive => greater.
* equal is possible if both operands are zeros. */
if( Sgl_iszero_exponentmantissa(left)
&& Sgl_iszero_exponentmantissa(right) )
{
Set_status_cbit(Equal(cond));
}
else if( Sgl_isone_sign(left) )
{
Set_status_cbit(Lessthan(cond));
}
else
{
Set_status_cbit(Greaterthan(cond));
}
}
/* Signs are the same. Treat negative numbers separately
* from the positives because of the reversed sense. */
else if( Sgl_all(left) == Sgl_all(right) )
{
Set_status_cbit(Equal(cond));
}
else if( Sgl_iszero_sign(left) )
{
/* Positive compare */
if( Sgl_all(left) < Sgl_all(right) )
{
Set_status_cbit(Lessthan(cond));
}
else
{
Set_status_cbit(Greaterthan(cond));
}
}
else
{
/* Negative compare. Signed or unsigned compares
* both work the same. That distinction is only
* important when the sign bits differ. */
if( Sgl_all(left) > Sgl_all(right) )
{
Set_status_cbit(Lessthan(cond));
}
else
{
Set_status_cbit(Greaterthan(cond));
}
}
return(NOEXCEPTION);
}
/*ARGSUSED*/
int
sgl_fsqrt(sgl_floating_point *srcptr, sgl_floating_point *dstptr,
unsigned int *status)
{
register unsigned int src, result;
register int src_exponent, newbit, sum;
register int guardbit = false, even_exponent;
src = *srcptr;
/*
* check source operand for NaN or infinity
*/
if ((src_exponent = Sgl_exponent(src)) == SGL_INFINITY_EXPONENT) {
/*
* is signaling NaN?
*/
if (Sgl_isone_signaling(src)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(src);
}
/*
* Return quiet NaN or positive infinity.
* Fall thru to negative test if negative infinity.
*/
if (Sgl_iszero_sign(src) || Sgl_isnotzero_mantissa(src)) {
*dstptr = src;
return(NOEXCEPTION);
}
}
/*
* check for zero source operand
*/
if (Sgl_iszero_exponentmantissa(src)) {
*dstptr = src;
return(NOEXCEPTION);
}
/*
* check for negative source operand
*/
if (Sgl_isone_sign(src)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_makequietnan(src);
*dstptr = src;
return(NOEXCEPTION);
}
/*
* Generate result
*/
if (src_exponent > 0) {
even_exponent = Sgl_hidden(src);
Sgl_clear_signexponent_set_hidden(src);
}
else {
/* normalize operand */
Sgl_clear_signexponent(src);
src_exponent++;
Sgl_normalize(src,src_exponent);
even_exponent = src_exponent & 1;
}
if (even_exponent) {
/* exponent is even */
/* Add comment here. Explain why odd exponent needs correction */
Sgl_leftshiftby1(src);
}
/*
* Add comment here. Explain following algorithm.
*
* Trust me, it works.
*
*/
Sgl_setzero(result);
newbit = 1 << SGL_P;
while (newbit && Sgl_isnotzero(src)) {
Sgl_addition(result,newbit,sum);
if(sum <= Sgl_all(src)) {
/* update result */
Sgl_addition(result,(newbit<<1),result);
Sgl_subtract(src,sum,src);
}
Sgl_rightshiftby1(newbit);
Sgl_leftshiftby1(src);
}
/* correct exponent for pre-shift */
if (even_exponent) {
Sgl_rightshiftby1(result);
}
/* check for inexact */
if (Sgl_isnotzero(src)) {
if (!even_exponent & Sgl_islessthan(result,src))
Sgl_increment(result);
guardbit = Sgl_lowmantissa(result);
Sgl_rightshiftby1(result);
/* now round result */
switch (Rounding_mode()) {
case ROUNDPLUS:
Sgl_increment(result);
break;
case ROUNDNEAREST:
/* stickybit is always true, so guardbit
* is enough to determine rounding */
if (guardbit) {
Sgl_increment(result);
}
break;
}
/* increment result exponent by 1 if mantissa overflowed */
if (Sgl_isone_hiddenoverflow(result)) src_exponent+=2;
if (Is_inexacttrap_enabled()) {
Sgl_set_exponent(result,
((src_exponent-SGL_BIAS)>>1)+SGL_BIAS);
*dstptr = result;
return(INEXACTEXCEPTION);
}
else Set_inexactflag();
}
