Re^3: Is this a sane/safe way to pass an aref into a C function? (XS<Perl)


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Re^3: Is this a sane/safe way to pass an aref into a C function? (XS<Perl)

by Marshall (Canon)

on Jan 23, 2017 at 03:44 UTC ( [id://1180134]=note: print w/replies, xml )

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in reply to Re^2: Is this a sane/safe way to pass an aref into a C function? (XS<Perl)
in thread Is this a sane/safe way to pass an aref into a C function?

Good thread.
I tried to get this code working with Active State 5.20, but I don't have right "formula" to do that on my current little laptop. Is there a FAQ on this? What compiler is necessary, etc...?

PS: I think your check() would be more "C like" coded something like this:

void check(unsigned char* n, int len)
{
    while (len--)
    {
       printf ("%d\n", *n++); 
    }
}
[download]

The variable: int i is unnecessary. With the C calling convention on 32 bit machine, check() is passed a 32 bit pointer to n (pointer to an array of unsigned bytes) and a 32 bit signed integer, len on the stack. These are copies for the subroutine to modify and use as it wishes.

This n[i] syntax is often coded by the compiler as (n i*size_of_n) plus base address. Whereas n++ is coded as n plus the size_of_n.