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#105 OnBC: Faulty division of negative long integers
OnBoardC 2.3
Division of one long integer by another one seems to
work only if both of them have the same sign.
{
Int32 a, b, c;
...
c = a / b;
}
For a=-6, b=3 ---> c = -6 results.
For a=6, b=-3 ---> c = -6 results.
For a=-6, b=-3 ---> c = 2 results. OK
For a=6, b=3 ---> c = 2 results. OK
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Hmm... I think I found a similar trouble, but I just noted
it down in a memo quickly so this might not be right:
Int x, z;
PointType p; //both members are of type int
//...
(x-p.x)/z ---> if x-p.x works out to be negative, the result
is the value of x-p.x, ignoring "/z"
If x is a double the trouble goes away (I'm guessing that
would cast p.x to a double, which results in casting z to
double and appearantly there is no bug there).
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I can not recreate this BUG. (OnBC/Asm v.2.3)
static Boolean test(void){
Int32 a, b, c;
a = -6;
b = 3;
c = a/b;
if (c = -2)
return 0; // upon success!
else
return 1; // upon failure.
}
This function will return 0 for me.
Anyone else having other results?
/John
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John,
please change the line
if (c = -2)
of your test function by
if (c == -2)
. Otherwise the function will always show the same result
regardless of the values used. On my m515 that code returns 1.
I repeated the test using first Int16 and then Int8. But the
error occured when using Int32 only.
Ari
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Hi all,
I was wrong!
There IS a BUG in v.2.3!
Thanks for correcting mw!
/John
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Hi all,
I was wrong!
There IS a BUG in v.2.3!
Thanks for correcting mw!
/John
Logged In: YES
user_id=574706
Hi all,
I was wrong!
There IS a BUG in v.2.3!
Thanks for correcting mw!
/John
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user_id=574706
Yes to fixing this.
static Boolean test(void){
Int32 a, b, c;
a = -6;
b = 3;
c = a/b;
if (c == -2) // Thanks Ari.
return 0; // upon success!
else
return 1; // upon failure.
}
It strange: this litte function assembles to aprox. 300 bytes
of code!