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#define EFLAGS_INTERRUPTS (1 << 9)
#define EFLAGS_DEFAULTS (1 << 1)

namespace Tasks
{
	uint_32 next_pid;
	uint_32 cpid = 0;

	Task tasks[NUM_TASKS];

	void idle()
	{
		while (1)
			cdebug << "Idling\n";
	}

	extern "C" void do_bootstrap_task_switch(uint_32 newesp);
	void setup()
	{
		int n = 3;
		for (int i = 0; i < NUM_TASKS; i++)
		{
			GDT::set(GDT::gdt[n], (uint_32)&tasks[i].ldt, sizeof(tasks[i].ldt) - 1, 0x20, 0);
			n++;
		}
		
		// give the kernel its own task
		tasks[0].name = "[kernel]";
		
		// set up the ldt
		GDT::set(tasks[0].ldt[0], 0, 0xFFFFFFFF, 0x9A, 0xCF);
		GDT::set(tasks[0].ldt[1], 0, 0xFFFFFFFF, 0x92, 0xCF);
		
		// and the stack
		uint_32 *stack = new uint_32[PROCESS_STACK_SIZE / 4];
		assert(stack != NULL);
		
		tasks[0].stack = stack;
		int stack_index = (PROCESS_STACK_SIZE / 4) - 1;

		stack[stack_index--] = EFLAGS_DEFAULTS | EFLAGS_INTERRUPTS; // eflags
		stack[stack_index--] = 0x08;	// cs
		stack[stack_index--] = (uint_32)(&idle); // eip
		stack[stack_index--] = 0;	// ebp
		stack[stack_index--] = 0;	// not used for anything
		stack[stack_index--] = 0;	// edi
		stack[stack_index--] = 0;	// esi
		stack[stack_index--] = 0;	// edx
		stack[stack_index--] = 0;	// ecx
		stack[stack_index--] = 0;	// ebx
		stack[stack_index--] = 0;	// eax
		stack[stack_index--] = 0x10;	// ds
		stack[stack_index--] = 0x10;	// es
		stack[stack_index--] = 0x10;	// fs
		stack[stack_index--] = 0x10;	// gs
		stack[stack_index--] = 0x10;	// ss
		
		tasks[0].esp = (uint_32)&stack[stack_index + 1];
		do_bootstrap_task_switch(tasks[0].esp);
	}
	
	extern "C" void do_task_switch(uint_32 *oldesp, uint_32 eip, uint_32 newesp, uint_32 newldt);
	void task_switch(IDT::regs_t *regs)
	{
		do_task_switch(&tasks[cpid].esp, regs->eip, tasks[cpid].esp, (3 + cpid) << 3);
	}
};

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global do_task_switch
do_task_switch:
	; save old task's state
	pushf
	push cs
	push dword [esp+8+12]
	pusha
	push ds
	push es
	push fs
	push gs
	push ss
	mov eax, [esp+64+16]
	mov [eax], esp

	; and load the new one
	lldt [esp+64+4]
	mov esp, [esp+64+8]
	pop ss
	pop gs
	pop fs
	pop es
	pop ds
	popa
	iret

global do_bootstrap_task_switch
do_bootstrap_task_switch:
	mov esp, [esp+4]
	pop ss
	pop gs
	pop fs
	pop es
	pop ds
	popa
	iret

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; Two bytes are already pushed before this: the error code and interrupt number.
isr_common:
	pusha
	push ds
	push es
	push fs
	push gs
	push ss
	mov eax, 0x10
	mov ds, eax
	mov es, eax
	mov fs, eax
	mov gs, eax
	mov ss, eax
	push esp
	call isr_handler
	add esp, 4
	pop ss
	pop gs
	pop fs
	pop es
	pop ds
	popa
	add esp, 8
	iret

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mov [eax->esp], esp

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; IRQ 0 (ISR 32) is a special case, since it's used for the scheduler also
extern current_esp
global _irq0
_irq0:
	pusha
	pushf
	mov eax, [current_esp]
	mov [eax], esp
	jmp isr32

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extern current_esp
global do_task_switch
do_task_switch:
	mov eax, [current_esp]
	mov esp, [eax]
	popa
	popf
	iret

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qemu: fatal: Trying to execute code outside RAM or ROM at 0xc0a19c60

EAX=00000000 EBX=00000000 ECX=00000000 EDX=00000000
ESI=00000000 EDI=00000000 EBP=00000000 ESP=001b94bc
EIP=c0a19c60 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0

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set(idt[32], (isrfunc_t)_irq0, 0x08, 0x8E);

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set(idt[32], (isrfunc_t)[b]&[/b]_irq0, 0x08, 0x8E);