#ifndef INTERRUPTS_H
#define INTERRUPTS_H

#include "stdint.h"

#include "port.h"
#include "tasks.h"

// total number of supported interrupts
#define NOF_INTERRUPTS 256

// offset for hardware interrupts
#define IRQ_BASE 0x20

// TODO: for now the code segment is the first entry in the boot GDT	
// temporary, should be a gdt module with functions to retrieve the
// current code segment selector
#define GDT_CODE_SEGMENT_SELECTOR 8

// TCC 0.9.26 bug?, __attribute__( ( packed ) ) on structs not working,
// also not working on members.. resorting to pragmas
#if defined( __TINYC__ )
#pragma pack(1)
#endif

// packed IDT structure, note TCC needs every member to have a packed
// attribute, GCC/Clang are happy with the packed attribute at the
// structure level
typedef struct interrupt_gate_descriptor_t {
	uint16_t handler_address_low_bits;
	uint16_t gdt_code_segment_selector;
	uint8_t reserved;
	uint8_t access;
	uint16_t handler_address_high_bits;
} __attribute__( ( packed ) ) interrupt_gate_descriptor_t;

#if defined( __TINYC__ )
#pragma pack()
#endif

#if defined( __TINYC__ )
#pragma pack(1)
#endif

typedef struct {
	uint16_t size;
	uint32_t base;	
} __attribute__( ( packed ) ) interrupt_descriptor_table_pointer_t;

#if defined( __TINYC__ )
#pragma pack()
#endif

struct interrupt_t;
struct interrupt_handler_t;

typedef uint32_t (*interrupt_handler_func_t)( struct interrupt_handler_t *handler, uint32_t esp );

typedef struct interrupt_handler_t {
	uint8_t interrupt_no;
	struct interrupt_t *interrupt;
	interrupt_handler_func_t handle;
	void *driver;
} interrupt_handler_t;

void interrupt_handler_init_void( interrupt_handler_t *handler, struct interrupt_t *interrupt );
void interrupt_handler_init( interrupt_handler_t *handler, uint8_t interrupt_no, struct interrupt_t *interrupt, interrupt_handler_func_t handle, void *driver );

typedef struct interrupt_t {
	interrupt_descriptor_table_pointer_t idt_pointer;
	interrupt_gate_descriptor_t descriptor_table[NOF_INTERRUPTS];
	interrupt_handler_t interrupt_handler[NOF_INTERRUPTS];
	task_manager_t *task_manager;
	// PIC master control register: command and status register
	port8_t PIC_master_control;
	// PIC master data register: interrupt mask and data register
	port8_t PIC_master_data;
	// since PC/AT we always have a slave PIC, we don't support the PC/XT architecture
	// with just one PIC
	port8_t PIC_slave_control;
	port8_t PIC_slave_data;
} interrupt_t;

void interrupts_enable( void );
void interrupts_disable( void );
void interrupts_init( interrupt_t *interrupt, uint16_t gdt_code_segment_selector, task_manager_t *task_manager );
void interrupts_register_interrupt_gate( interrupt_t *interrupt,
	uint8_t interrupt_no, uint16_t gdt_code_segment_selector,
	void (*helper_handler)( ), uint8_t privilege_level, uint8_t descriptor_type );
void interrupts_register_interrupt_handler( interrupt_handler_t handler );

void interrupts_load_idt( interrupt_descriptor_table_pointer_t *idt_pointer );

uint32_t interrupts_handle_interrupt( interrupt_t *interrupt, uint8_t interrupt_no, uint32_t esp );

uint32_t interrupts_handle_static_interrupt( uint8_t interrupt_no, uint32_t esp );

uint32_t interrupts_exception_division_by_zero( interrupt_handler_t *handler, uint32_t esp );

uint32_t interrupts_interrupt_PIT( interrupt_handler_t *handler, uint32_t esp );

void interrupts_ignore_request( );
void interrupts_handle_exception_0x00( );
void interrupts_handle_irq_0x00( );
void interrupts_handle_irq_0x01( );
void interrupts_handle_irq_0x0C( );

// later: tasks and stacks, queues

#endif // INTERRUPTS_H