help with XS (Newx and

Bpl has asked for the wisdom of the Perl Monks concerning the following question:

Hi monkers, in those days, I am writing an XS library but I am having some difficulties converting the C's malloc and memset instruction into the perl's equivalent (for the perlClib) the code snippet is:


# C code
r = (AirLorconDriver *) malloc(sizeof(AirLorconDriver *));

# where AirLorconDriver is:

struct lorcon_driver {
    struct lorcon_driver *next;

    char *name;
    char *details;

    lorcon_drv_init init_func;
    lorcon_drv_probe probe_func;
}lorcon_driver_t;
typedef lorcon_driver_t AirLorconDriver;
[download]

This was the malloc's problem, the memset snippet is:

# C code
memset(l_packet, 0, sizeof(AirLorconDriver)); # where l_packet is:

AirLorconDriver *l_packet;
[download]

Can anyone help me translating those 2 obscure C function into perl's Newx and Zero functions? Thanks Edoardo Mantovani, 2020

Comment on help with XS (Newx and Select or Download Code

Replies are listed 'Best First'.
Re: help with XS (Newx and by Corion (Patriarch) on Sep 05, 2020 at 18:33 UTC
Without testing it and actually going from the perlapi documentation for `Newxz`, the following should give you an allocated buffer, filled with zeroes: `AirLorconDriver * l_packet; Newxz( l_packet, 1, AirLorconDriver); /* Remember to use SafeFree() to release the memory pointed to by l_pa +cket /` [download] Update*: Also see perlguts for more discussion of `Newx()` and friends	[reply] [d/l] [select]
Re^2: help with XS (Newx and by Bpl (Scribe) on Sep 05, 2020 at 19:23 UTC
Hi! sorry if I ask, but the `Newxz( l_packet, 1, AirLorconDriver);` [download] would be referred to the memset or to the malloc function? because in the malloc case (`r = (AirLorconDriver ) malloc(sizeof(AirLorconDriver ) );`) there isn't any packet_l. thanks Edoardo Mantovani, 2020	[reply] [d/l] [select]
Re^3: help with XS (Newx and by Corion (Patriarch) on Sep 05, 2020 at 19:40 UTC
`Newxz` is a combined `malloc()` plus `memset()` call, see perlapi and perlguts on it. I think the usage would be to declare the pointer to your struct and then to have it allocated and zeroed like this: `Newxz( r, 1, AirLorconDriver );` [download]	[reply] [d/l] [select]