xfnw/plan9fox
1
0
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity

frexp: handle NaN values (from sources)

Browse source
This commit is contained in:
cinap_lenrek 2013-05-01 16:44:04 +02:00
parent 27f65a138a
commit decade55c6
2 changed files with 23 additions and 11 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

16
sys/src/ape/lib/ap/plan9/frexp.c
View file

@ -6,6 +6,7 @@
#define MASK 0x7ffL
#define SHIFT 20
#define BIAS 1022L
#define SIG 52
typedef union
{
@ -25,13 +26,18 @@ typedef union
double
frexp(double d, int *ep)
{
Cheat x;
Cheat x, a;
if(d == 0) {
*ep = 0;
return 0;
}
*ep = 0;
/* order matters: only isNaN can operate on NaN */
if(isNaN(d) || isInf(d, 0) || d == 0)
return d;
x.d = d;
a.d = fabs(d);
if((a.ms >> SHIFT) == 0){ /* normalize subnormal numbers */
x.d = (double)(1ULL<<SIG) * d;
*ep = -SIG;
}
*ep = ((x.ms >> SHIFT) & MASK) - BIAS;
x.ms &= ~(MASK << SHIFT);
x.ms |= BIAS << SHIFT;

18
sys/src/libc/port/frexp.c
View file

@ -9,18 +9,24 @@
#define MASK 0x7ffL
#define SHIFT 20
#define BIAS 1022L
#define SIG 52
double
frexp(double d, int *ep)
{
FPdbleword x;
FPdbleword x, a;
if(d == 0) {
*ep = 0;
return 0;
}
*ep = 0;
/* order matters: only isNaN can operate on NaN */
if(isNaN(d) || isInf(d, 0) || d == 0)
return d;
x.x = d;
*ep = ((x.hi >> SHIFT) & MASK) - BIAS;
a.x = fabs(d);
if((a.hi >> SHIFT) == 0){ /* normalize subnormal numbers */
x.x = (double)(1ULL<<SIG) * d;
*ep = -SIG;
}
*ep += ((x.hi >> SHIFT) & MASK) - BIAS;
x.hi &= ~(MASK << SHIFT);
x.hi |= BIAS << SHIFT;
return x.x;