void IOScheduler(){
if(param_ptr->device_id==TERMINAL||param_ptr->device_id==COM_PORT){
IOD *Descriptor = sys_alloc_mem(sizeof(IOD));
Descriptor->ppt = COP;
strcpy(Descriptor->PCBName,COP->processName);
Descriptor->buffer = param_ptr->buf_addr;
Descriptor->count = param_ptr->count_addr;
Descriptor->requestType = param_ptr->op_code;
if(param_ptr->device_id==TERMINAL){
if(TerminalQueue-> count == 0){
TerminalQueue->head = Descriptor;
TerminalQueue->tail = Descriptor;
TerminalQueue->count = 1;
ProcessIORequest(1);
}else{
TerminalQueue->tail->next = Descriptor;
TerminalQueue->tail = TerminalQueue->tail->next;
TerminalQueue->count++;
}
}else if(param_ptr->device_id==COM_PORT){
if(Com_PortQueue-> count == 0){
Com_PortQueue->head = Descriptor;
Com_PortQueue->tail = Descriptor;
Com_PortQueue->count = 1;
ProcessIORequest(2);
}else{
Com_PortQueue->tail->next = Descriptor;
Com_PortQueue->tail = Com_PortQueue->tail->next;
Com_PortQueue->count++;
}
}
COP->state = 0;
insertPCB(COP);
//blockPCB(COP->processName);
}
}
void HALdisplayDriver ()
{
do
{
BlockSignals ();
if (messageFromHALos)
{
messageFromHALos = 0;
GetMessageFromHALos ();
ProcessIORequest ();
SendMessageToHALos ();
}
UnblockSignals ();
} while (1);
return;
}
void interrupt sys_call(void){
static IOD *temp;
//Saves the ss and sp register to a temp storage
ss_save2 = _SS;
sp_save2 = _SP;
COP->stack = (unsigned char *)MK_FP(ss_save2,sp_save2);
//Updates the stacktop for context switch
//Access Parameters that sys_req placed on the stack
param_ptr = (params*)(COP->stack+sizeof(context));
//Switching to a temp stack
new_ss = FP_SEG(sys_stack);
new_sp = FP_OFF(sys_stack)+ SYS_STACK_SIZE;
_SS = new_ss;
_SP = new_sp;
trm_getc();
if(TerminalQueue->event_flag==1 && TerminalQueue->count > 0){
TerminalQueue->event_flag = 0;
temp = TerminalQueue->head;
TerminalQueue->head = TerminalQueue->head->next;
unblockPCB(temp->ppt->processName);
sys_free_mem(temp);
TerminalQueue->count--;
if(TerminalQueue->count!=0){
ProcessIORequest(1);
}
}
if(Com_PortQueue->event_flag==1 && Com_PortQueue->count > 0){
Com_PortQueue->event_flag = 0;
temp = Com_PortQueue->head;
Com_PortQueue->head = Com_PortQueue->head->next;
unblockPCB(temp->ppt->processName);
sys_free_mem(temp);
Com_PortQueue->count--;
if(Com_PortQueue->count!=0){
ProcessIORequest(1);
}
}
//Process is idle
if (param_ptr -> op_code == IDLE){
//Sets state to running and adds it back into the readyQueue
COP -> state = 2;
PriorityEnqueue(readyQueue,COP);
}
//Process is completed and ready for deletion
if (param_ptr -> op_code == EXIT){
//Frees the memory of the PCB and sets the PCB to NULL
freePCB(COP);
COP = NULL;
}
if (param_ptr -> op_code == READ ||param_ptr -> op_code == WRITE ||param_ptr -> op_code == CLEAR ||param_ptr -> op_code == GOTOXY ){
IOScheduler();
}
//Dispatches the next process in the readyQueue
dispatch();
}
