Re: [pdf-devel] Issues with bug FS#105

[Dave Johnson]

Can i get a copy of the application.

> On Mar 30, 2010 3:08 PM, "gerel" <address@hidden> wrote:
>
>
> Hi,
>
> I've tried to reproduce the bug there named. I couldn't.
> However, I believe there is some issue with signs.
> I made some tests myself regarding the number sign that should be returned.  The
> mod operator native implementation works like this:
>
> INPUT
> ##
> #include <stdio.h>
> int main (){
>         printf ("5 % 3: %d\n",  5%3);
>         printf ("5 % -3: %d\n",  5%-3);
>         printf ("-5 % 3: %d\n", -5%3);
>         printf ("-5 % -3: %d\n\n", -5%-3);
>
>         printf ("3 % 5: %d\n",  3%5);
>         printf ("3 % -5: %d\n",  3%-5);
>         printf ("-3 % 5: %d\n", -3%5);
>         printf ("-3 % -5: %d\n", -3%-5);
> }
> ##
> OUTPUT:
> address@hidden:~$ ./a.out
> 5 % 3: 2
> 5 % -3: 2
> -5 % 3: -2
> -5 % -3: -2
>
> 3 % 5: 3
> 3 % -5: 3
> -3 % 5: -3
> -3 % -5: -3
> ##
>
> That means that the result sign is _only_ decided on the dividend sign.  In the
> current code for pdf_i64_mod() (built-in implementation), It says:
> ##
>       [...]
>
>       /*Now check the signs fo divisor and dividend*/
>       if (pdf_i64_cmp(divisor,zero) < 0)
>         {
>           result_sign = -1;
>           pdf_i64_abs(&divisor,divisor, p_status);
>         }
>       if (pdf_i64_cmp(dividend,zero) < 0)
>         {
>           pdf_i64_abs(&dividend,dividend, p_status);
>           if (result_sign == -1)
>             {
>               result_sign = -1;
>             }
>           else
>             {
>               result_sign = -1;
>             }
>         }
>
>       [...]
> ###
>
> If the variable named "result_sign" is deciding the returned number sign.
> I believe it should be something like this instead,
>
> ##
>       [...]
>
>       /*Now check the signs fo divisor and dividend*/
>       if (pdf_i64_cmp(divisor,zero) < 0)
>         {
>           pdf_i64_abs(&divisor,divisor, p_status);
>         }
>       if (pdf_i64_cmp(dividend,zero) < 0)
>         {
>           pdf_i64_abs(&dividend,dividend, p_status);
>           result_sign = -1;
>         }
>
>       [...]
> ###
>
> I may be wrong, I didn't read the whole function code, because I'm not familiar
> with the Knuth method.
>
> Despite that, I tried the above proposed modification and no new test fails. It
> seems to work fine or do nothing. :-)
>
> Any comments ?
>
> cheers,
>
> -gerel