Re: [ECOS] Prototyping with the synthetic target.

[Chuck McParland <cpmcparland at lbl dot gov>]

Many thanks, that clears up quite a bit.  I'll
give it a try.

Cheers,
Chuck McParland

Wouter Cloetens wrote:

> On Thu, Aug 01, 2002 at 10:27:14AM -0700, Chuck McParland wrote:
> > You mentioned using sockets at the hal_sys level.  I assume you
> > had to link with the Linux libraries to get the socket calls. Wouldn't this
> > cause conflicts with the ecos synthetic lib?
>
> What I did was to use the socketcall system call directly. It's a single
> system call that provides all the socket call services. See the linux
> kernel source, net/socket.c, and include/linux/net.h for the identifier
> values of the socket calls.
>
> Here's a sample implementation of a few calls:
>
> #define SYS_SOCKET      1               /* sys_socket(2) */
> #define SYS_BIND        2               /* sys_bind(2) */
>
> externC unsigned long cyg_hal_sys_socketcall(int call, unsigned long
> *args);
>
> static inline int machdep_socket(int domain, int type, int protocol)
> {
>     unsigned long args[3];
>     args[0] = domain;
>     args[1] = type;
>     args[2] = protocol;
>     return cyg_hal_sys_socketcall(SYS_SOCKET, (unsigned long *)&args);
> }
>
> static inline int machdep_bind(int sockfd, struct sockaddr *my_addr,
> socklen_t addrlen)
> {
>     unsigned long args[3];
>     args[0] = sockfd;
>     args[1] = (unsigned long)my_addr;
>     args[2] = (unsigned long)addrlen;
>     return cyg_hal_sys_socketcall(SYS_BIND, (unsigned long *)&args);
> }
>
> Instead of returning -1 and placing the error code in errno, the calls
> return the negative error code.
>
> Another thing you need to keep in mind when making calls in the synthetic
> Linux target, is that the scheduler seems to be signal driven. This
> means that any blocking system call is extremely likely to be
> interrupted, and return -EINTR. Shield that, like this:
>
> static int internal_send(int s, const void *data, size_t len, int flags)
> {
>     int err;
>
>     while (1)
>     {
>         err = machdep_send(s, data, len, flags);
>
>         if (err == -EAGAIN)
>         {
>             cyg_thread_delay(100);
>             cyg_thread_yield();
>             continue;
>         }
>         else if (err == -EINTR)
>             continue;
>         else
>             break;
>     }
>     return err;
> }
>
> Hope to have helped out.
>
> bfn, Wouter
>
> --
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> and search the list archive: http://sources.redhat.com/ml/ecos-discuss


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