void _dispatch( void ) {
int i;
Status status;
// select a process from the highest-priority
// ready queue that is not empty
for( i = 0; i < N_READYQ; ++i ) {
do {
if( _q_empty(_ready[i]) ) {
break;
}
// found one - make it the currently-running process
status = _q_remove( _ready[i], (void **) &_current );
if( status == SUCCESS ) {
// check to see if it needs to be cleaned up
if( _current->state == KILLED ) {
// yes - deallocate it
_cleanup( _current );
// go back and re-check this queue
continue;
}
_current->state = RUNNING;
_current->quantum = STD_QUANTUM;
return;
} else {
_kpanic( "_dispatch", "readyq deque status %s",
status );
}
} while( 1 );
}
_kpanic( "_dispatch", "no non-empty readyq", EMPTY_QUEUE );
}
status_t _q_append( queue_t *queue, void *data, key_t key ) {
qnode_t *qnode;
status_t stat;
// sanity check
if( queue == NULL ) {
// INCONSISTENCY
_kpanic( "_q_append", "null queue", 0 );
}
// first, get a qnode structure
stat = _qnode_alloc( &qnode );
if( stat != E_SUCCESS ) {
return( stat );
}
// fill in the necessary information
qnode->key = key;
qnode->data = data;
// add the node to the end of the queue
if( _q_empty(queue) ) {
queue->head = qnode;
} else {
queue->tail->next = qnode;
}
qnode->next = NULL;
qnode->prev = queue->tail;
queue->tail = qnode;
queue->length += 1;
return( E_SUCCESS );
}
status_t _q_remove( queue_t *queue, void **data ) {
qnode_t *qnode;
// sanity check
if( queue == NULL || data == NULL ) {
return( E_BAD_PARAM );
}
// if no nodes in the queue, we're done
if( _q_empty(queue) ) {
return( E_EMPTY );
}
// remove the first node from the queue
qnode = queue->head;
queue->length -= 1;
queue->head = qnode->next;
if( queue->head == NULL ) {
queue->tail = NULL;
} else {
queue->head->prev = NULL;
}
// return the data field to the caller
*data = qnode->data;
// propogate the qnode deallocation status
return( _qnode_free( qnode ) );
}
status_t _q_insert( queue_t *queue, void *data, key_t key ) {
qnode_t *qnode;
qnode_t *curr;
status_t stat;
// sanity check
if( queue == NULL ) {
return( E_BAD_PARAM );
}
// allocate a queue node
stat = _qnode_alloc( &qnode );
if( stat != E_SUCCESS ) {
return( stat );
}
// fill in the necessary information
qnode->key = key;
qnode->data = data;
qnode->prev = NULL;
qnode->next = NULL;
// if the queue is empty, no need to find the "right" place
if( _q_empty(queue) ) {
queue->head = qnode;
queue->tail = qnode;
queue->length = 1;
return( E_SUCCESS );
}
// no comparison routine means append
if( queue->compare == NULL ) {
queue->tail->next = qnode;
qnode->prev = queue->tail;
queue->tail = qnode;
queue->length += 1;
return( E_SUCCESS );
}
//
// traverse the queue looking for the correct insertion point,
// as indicated by the built-in comparison routine
//
curr = queue->head;
while( curr != NULL && queue->compare(curr,qnode) <= 0 ) {
curr = curr->next;
}
// add at the end of the queue
if( curr == NULL ) {
queue->tail->next = qnode;
qnode->prev = queue->tail;
queue->tail = qnode;
queue->length += 1;
return( E_SUCCESS );
}
// insert in the middle of the queue
qnode->next = curr;
if( curr->prev == NULL ) {
queue->head = qnode;
} else {
curr->prev->next = qnode;
qnode->prev = curr->prev;
}
curr->prev = qnode;
queue->length += 1;
return( E_SUCCESS );
}
status_t _q_remove_by_key( queue_t *queue, void **data, key_t key ) {
qnode_t *qnode;
status_t stat;
// verify that our parameters are usable
if( queue == NULL || data == NULL ) {
return( E_BAD_PARAM );
}
// if the queue is empty, nothing to do
if( _q_empty(queue) ) {
return( E_EMPTY );
}
// if there is no specialized removal routine, do an ordinary remove
if( queue->remove == NULL ) {
return( _q_remove(queue,data) );
}
//
// Traverse the queue, looking for the correct element.
// Use the built-in removal routine to determine when
// we have found the correct entry.
//
qnode = queue->head;
while( qnode != NULL && !queue->remove(qnode->key,key) ) {
qnode = qnode->next;
}
// did we find the one we wanted?
if( qnode == NULL ) {
return( E_NOT_FOUND );
}
// found the correct node - unlink it from the queue
if( qnode->prev != NULL ) {
qnode->prev->next = qnode->next;
} else {
queue->head = qnode->next;
}
if( qnode->next != NULL ) {
qnode->next->prev = qnode->prev;
} else {
queue->tail = qnode->prev;
}
queue->length -= 1;
// return the data from the node
*data = qnode->data;
// release the qnode
//
// INCONSISTENCY: _q_remove() just propogates the status
stat = _qnode_free( qnode );
if( stat != E_SUCCESS ) {
_kpanic( "_q_remove_by_key", "qnode free failed, %s", stat );
}
return( E_SUCCESS );
}
/**
* Writes the given character to the focused process, if one exists. Otherwise
* the character is discarded.
*
* @param c The character to write
*/
void _ps2_write_to_active( char c ){
// Grab focused process
Pid active_p = get_active_pid();
// Throw away the character if there is no focused process
if( active_p == 0 ){
return;
}
// Find the IO-request for this process
int index = 0;
while( index < TOTAL_IO_REQS ){
if( requests[ index ]->pid == active_p )
break;
index ++;
}
if( index == TOTAL_IO_REQS )
return; // The focused process does not want input
// Write the character
// Check if we need to return a special character, or write to buf
//c_printf( "Index: %d Size: %d\n", requests[ index ]->index, requests[ index ]->size);
char *buf = requests[ index ]->buf;
Uint8 flags = 0;
//c_printf(" Writing Buf Addr: 0x%x\n", buf);
Uint32 currentCr3 = _isr_vmem_getcr3();
_vmeml2_change_page(requests[ index ]->pdt);
//c_printf(" Writing Buf Addr: 0x%x 0x%x\n", buf, buf+sizeof(char));
if( requests[ index ]->size == 0 ){
buf[1] = c;
if( shift_pressed )
flags = flags | 4;
if( alt_pressed )
flags = flags | 2;
if( ctrl_pressed )
flags = flags | 1;
buf[0] = (char) flags;
Pcb *pcb = _ps2_remove_from_queue( index );
_ps2_delete_request( index );
_sched( pcb );
}
else{
// We need to print the character for the user
screen_info* si = get_screen_info( active_p );
gl_putchar_s( c, si );
// store the character
int i = requests[ index ]->index;
if( c != '\n'){
buf[ i ] = c;
requests[ index ]->index = i + 1;
}
// stop reading if full, or newline
if( i == requests[ index ]->size || c == '\n' ){
buf[ i ] = '\0';
// pull from IO-blocking queue
if( !_q_empty( _buf_block ) ){
Pcb *pcb = _ps2_remove_from_queue( index );
_sched( pcb );
}
else{
// did someone forcefully remove it!?!
c_printf( "keyboard, write active: buffered block queue is"
" empty???\n" );
}
// Delete the process from our IO request array
_ps2_delete_request( index );
}
}
_vmeml2_change_page( currentCr3);
}