Re: [gnet] Using pack to pack an array

[Anna <christiana hipointcoffee com>]

On Wed, Jul 26, 2006 at 10:26:19PM +0200, Jon Kristensen wrote:
> Hello people!
> 
> First of all, thanks for a great library! :o)
> 
> My problem is that I want to send a standard C++ array of structs using
> pack, while I can't figure out a way to do it. This is what I want to
> pack (and unpack):
> 
> #define MAX_NUMBER_OF_CLIENTS 10
> 
> struct pos
> {
> 	int x, y;
> };
> 
> static pos positions[MAX_NUMBER_OF_CLIENTS];

try...

typedef
struct pos
{
	int x, y;
} pos_t ;

typef
struct mypacket
{
	pos_t positions[MAX_NUMBER_OF_CLIENTS];
} mypacket_t; 

int main()
{
    printf("%d\n", sizeof(mypacket_t) );

    /* that should print a number that's (2*MAX_NUMBER_OF_CLIENTS),
     * which means it's already serialized and ready to send over the
     * network.  just send it in a tcp stream. */
}

====================================================================
better yet.


typedef
struct pos
{
	int x, y;
} pos_t ;

typef
struct mypackethead
{
	uint32_t count;
} mypackethead_t; 

int make_packet_and_send()
{
    int              poscount   = 30;
    mypackethead_t * packet     = NULL;
    pos_t          * poses      = NULL;
    int              packetsize = 0;

    packetsize = sizeof(mypackethead_t) + (sizeof(pos_t) * poscount);

    /* allocate a continuous block of memory */
    packet = malloc( packetsize );

    if( packet )
    {
        memset( packet, 0, packetsize );
        packet->count = poscount;
	poses = (pos_t*)(packet+1);

	for(i = 0; i < poscount; i++ )
	{
	    poses[i].x = i*3 /* whatever */ ;
	    poses[i].y = i*25 /* whatever */ ;
	}

	send(packet, packetsize);

        /* make sure all data is "sent" (in kernel-space_ before freeing */
	free( packet );
    }

    ...;
}
====================================================================


ie, make your protocol flexible by adding information to the head of
each packet.

- Anna