OS_Return _OS_SemAlloc(OS_Sem_t *sem, UINT32 value)
{
OS_Return status;
if(!sem) {
status = BAD_ARGUMENT;
goto exit;
}
if(!g_current_process) {
status = PROCESS_INVALID;
goto exit;
}
// Get a free Semaphore resource from the pool
*sem = (OS_Sem_t) GetFreeResIndex(g_semaphore_usage_mask, MAX_SEMAPHORE_COUNT);
if(*sem < 0)
{
status = RESOURCE_EXHAUSTED;
goto exit;
}
OS_SemaphoreCB *semobj = (OS_SemaphoreCB *)&g_semaphore_pool[*sem];
// Block the thread resource
SetResourceStatus(g_semaphore_usage_mask, *sem, FALSE);
semobj->count = value;
semobj->owner = (OS_Process *) g_current_process;
_OS_QueueInit(&semobj->periodic_task_queue);
_OS_QueueInit(&semobj->aperiodic_task_queue);
status = SUCCESS;
exit:
return status;
}
OS_Return OS_CreateProcess(
OS_Process_t *process,
const INT8 *process_name,
UINT16 attributes,
void (*process_entry_function)(void *pdata),
void *pdata)
{
OS_Process *pcb;
if(!process)
{
FAULT("Invalid process");
return INVALID_ARG;
}
if(!process_entry_function || !process_name)
{
FAULT("OS_CreateProcess: invalid arguments");
return INVALID_ARG;
}
// Now get a free PCB resource from the pool
*process = (OS_Process_t) GetFreeResIndex(g_process_usage_mask, MAX_PROCESS_COUNT);
if(*process < 0)
{
FAULT("OS_CreateProcess failed for '%s': Exhausted all resources\n", g_current_process->name);
return RESOURCE_EXHAUSTED;
}
KlogStr(KLOG_GENERAL_INFO, "Creating process - ", process_name);
// Get a pointer to actual PCB
pcb = &g_process_pool[*process];
// Clear the process structure
memset(pcb, 0, sizeof(OS_Process));
// Copy process name
strncpy(pcb->name, process_name, OS_PROCESS_NAME_SIZE - 1);
pcb->name[OS_PROCESS_NAME_SIZE - 1] = '\0';
pcb->id = *process; // Assign a unique process id
pcb->attributes = attributes;
pcb->process_entry_function = process_entry_function;
pcb->pdata = pdata;
pcb->next = NULL;
#if ENABLE_MMU
pcb->ptable = _MMU_allocate_l1_page_table();
if(!pcb->ptable)
{
FAULT("OS_CreateProcess failed for '%s': No space in page table area\n", g_current_process->name);
return RESOURCE_EXHAUSTED;
}
// Now create a memory map for the task for the kernel space. Every process is going to have map for
// the whole kernel process. This makes it more efficient during system calls and interrupts
// by eliminating the need to change the page table.
// Note that this does not compromise the security as the user mode cannot read/write
// anything in the kernel memory map
_OS_create_kernel_memory_map(pcb->ptable);
#endif
// Block the process resource
SetResourceStatus(g_process_usage_mask, *process, FALSE);
// Add to the process list
if(g_process_list_tail)
{
g_process_list_tail->next = pcb;
g_process_list_tail = pcb;
}
else
{
g_process_list_head = g_process_list_tail = pcb;
}
return SUCCESS;
}