#include "thread.h"
#include "alloc.h"
#include "assert.h"
#include "interrupts.h"
#include "memory.h"
#include "string.h"
#include "thread.h"

struct tcb *create_thread(struct pcb *process, void (*routine)(void))
{
	static uint32_t tid = 1;
	struct tcb *new_tcb = vmalloc(sizeof(struct tcb));
	if (!new_tcb)
		return NULL;
	new_tcb->tid = tid++;

	new_tcb->esp0 = alloc_pages(STACK_SIZE, NULL);
	if (!new_tcb->esp0) {
		vfree(new_tcb);
		return NULL;
	}
	// set esp to "skip" the 4 GPRs and eip later to be used as the context
	// of the thread
	new_tcb->esp = new_tcb->esp0 + STACK_SIZE - 5 * 4;
	memcpy(new_tcb->esp + 4, routine, 4);
	new_tcb->process = process;
	new_tcb->next = NULL;
	new_tcb->state = NEW;

	struct tcb *it = process->thread_list;
	if (it) {
		while (it)
			it = it->next;
		it = new_tcb;
	}
	else {
		process->thread_list = new_tcb;
	}

	return new_tcb;
}

void delete_thread(struct tcb *thread)
{
	vfree(thread->esp0);
	struct tcb *it = thread->process->thread_list;
	assert(it);
	while (it->next != thread)
		it = it->next;
	it->next = it->next->next;
	vfree(thread);
}