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Added dnewlongobject(), function to convert double to long int.

This commit is contained in:
Guido van Rossum 1991-06-03 10:58:24 +00:00
parent ad40531aa1
commit 149e9ea24c
1 changed files with 39 additions and 0 deletions
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39
Objects/longobject.c
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@ -28,8 +28,14 @@ OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#include "allobjects.h"
#include "longintrepr.h"
#include <math.h>
#include <assert.h>
/* Forward: */
extern object *long_mul PROTO((longobject *, object *));
extern object *long_add PROTO((longobject *, object *));
extern object *long_neg PROTO((longobject *));
static int ticker; /* XXX Could be shared with ceval? */
#define INTRCHECK(block) \
@ -87,6 +93,39 @@ newlongobject(ival)
return (object *)v;
}
/* Create a new long int object from a C double */
object *
dnewlongobject(dval)
double dval;
{
longobject *v;
double frac;
int i, ndig, expo, neg;
neg = 0;
if (dval < 0.0) {
neg = 1;
dval = -dval;
}
frac = frexp(dval, &expo); /* dval = frac*2**expo; 0.0 <= frac < 1.0 */
if (expo <= 0)
return newlongobject(0L);
ndig = (expo-1) / SHIFT + 1; /* Number of 'digits' in result */
v = alloclongobject(ndig);
if (v == NULL)
return NULL;
frac = ldexp(frac, (expo-1) % SHIFT + 1);
for (i = ndig; --i >= 0; ) {
long bits = (long)frac;
v->ob_digit[i] = bits;
frac = frac - (double)bits;
frac = ldexp(frac, SHIFT);
}
if (neg)
v->ob_size = -v->ob_size;
return (object *)v;
}
/* Get a C long int from a long int object.
Returns -1 and sets an error condition if overflow occurs. */