//----------------------------------------------------------------------------------------------------//
// @func - sys_shmat
//! @desc
//! Attach to shared memory segment
//! - Lookup shared memory segment based on shmid and return pointer to start of the segment
//! @param
//! - shmid is the ID of the segment
//! - shmaddr is the address specification of the segment (ignored)
//! - shmflg is the attach flag (ignored)
//! @return
//! - Return the address of the segment on success and NULL on error.
//! errno set to,
//! EINVAL if shmid refers to an invalid shared memory segment
//! @note
//! - The shmaddr specification is discarded. We support attaches only to the start of the segment.
//! No memory mapping of any kind is done.
//! - shmflg is ignored because it applies to shmaddr
//----------------------------------------------------------------------------------------------------//
void* sys_shmat (int shmid, const void *shmaddr, int flag)
{
if ((shmid < 0) || (shmid >= N_SHM) || (shm_heap[shmid].shm_id == -1)) {
kerrno = EINVAL;
return NULL;
}
shm_heap[shmid].shm_nattch++ ;
shm_heap[shmid].shm_lpid = sys_get_currentPID();
return (void*)(shm_heap[shmid].shm_addr) ;
}
//----------------------------------------------------------------------------------------------------//
// @func - sys_sleep
//! @desc
//! Suspend current process for specified number of ticks
//! 1 tick = one timer interrupt received by the kernel
//! @param
//! - ms is the number of milliseconds to sleep this task.
//! @return
//! - Number of milliseconds unslept for. 0 - complete success
//! @note
//! - None
//----------------------------------------------------------------------------------------------------//
unsigned sys_sleep (unsigned int ms)
{
pid_t cpid = sys_get_currentPID();
if (add_tmr (cpid, ms) == -1)
return ms;
current_process->state = PROC_DELAY;
suspend ();
// Awaken here after timeout
return 0;
}
