[ECOS] Documentation sources

[Andrew Lunn]

> Great!  At last an engineer willing to do documentation without a gun held to 
> their head ;-)

No guarantee i will always write the documentation :-)

Anyway, heres the first contribution: (You probably want to pass
ispell over it, my English is terible)

void cyg_mutex_set_protocol(
    cyg_mutex_t *mutex,
    enum cyg_mutex_protocol protocol )

As described in section {Thread synchronization}, eCos's mutex can use
a number of scemes when dealing with priority inversion. This function
is used to set the protocol for the mutex. Protocol may take one of 3
values, CYG_MUTEX_NONE, CYG_MUTEX_INHERIT, CYG_MUTEX_CEILING. The
first indicates no inversion protocol will be used. The second uses
the SIMPLE inversion protocol, and the last uses the ceiling protocol.

void cyg_mutex_set_ceiling( 
     cyg_mutex_t *mutex, 
     cyg_priority_t priority );

When using the ceiling inversion protocol, this function allows the
ceiling thread priority of an obtained mutex to the set. 

cyg_priority_t cyg_thread_get_current_priority(cyg_handle_t thread)

Returns the current thread priority. If the thread is running at a
higher priority than normal due to priority inversion, this functions
returns the inverted priority, where as cyg_thread_get_priority()
returns the normal priority.