#ifndef _ACPI_H_
#define _ACPI_H_

#include <stdint.h>
#include <stddef.h>

struct rsdp {
 char signature[8];
 uint8_t checksum;
 char oemid[6];
 uint8_t revision;
 uint32_t rsdt_address;
} __attribute__((packed));

struct xsdp {
 char signature[8];
 uint8_t checksum;
 char oemid[6];
 uint8_t revision;
 uint32_t rsdt_address; // deprecated since version 2.0

 uint32_t length;
 uint64_t xsdt_address;
 uint8_t extended_checksum;
 uint8_t reserved[3];
} __attribute__((packed));

struct acpi_sdt_header {
	char signature[4];
	uint32_t len;
	uint8_t rev;
	uint8_t checksum;
	char oemid[6];
	char oem_tableid[8];
	uint32_t oem_revision;
	uint32_t creatorid;
	uint32_t creator_rev;
} __attribute__((packed));

struct rsdt {
	struct acpi_sdt_header header;
	uint32_t sdt_pointers[];
} __attribute__((packed));

struct xsdt {
	struct acpi_sdt_header header;
	uint64_t sdt_pointers[];
} __attribute__((packed));

struct generic_address {
	uint8_t address_space;
	uint8_t bid_width;
	uint8_t bit_offset;
	uint8_t access_size;
	uint64_t address;
} __attribute__((packed));

struct fadt {
	struct acpi_sdt_header header;
	uint32_t firmware_ctrl;
	uint32_t dsdt;

	uint8_t reserved;

	uint8_t prevered_power_management_profile;
	uint16_t sci_interrupt;
	uint32_t smi_command_port;
	uint8_t acpi_enable;
	uint8_t acpi_disable;
	uint8_t s4_bios_req;
	uint8_t pstate_control;

	uint32_t pm1a_event_block;
	uint32_t pm1b_event_block;

	uint32_t pm1a_control_block;
	uint32_t pm1b_control_block;

	uint32_t pm2_control_block;

	uint32_t pm_timer_block;

	uint32_t gpe0_block;
	uint32_t gpe1_block;

	uint8_t pm1_event_length;
	uint8_t pm1_control_length;
	uint8_t pm2_control_length;
	uint8_t pm_timer_length;

	uint8_t gpe0_length;
	uint8_t gpe1_length;
	uint8_t gpe1_base;

	uint8_t cstate_control;
	
	uint16_t worst_c2_latency;
	uint16_t worst_c3_latency;

	uint16_t flush_size;
	uint16_t flush_stride;

	uint8_t duty_offset;
	uint8_t duty_width;

	uint8_t day_alarm;
	uint8_t month_alarm;
	uint8_t century;

	uint16_t boot_arch_flags;

	uint8_t reserved_2;
	uint32_t flags;

	struct generic_address reset_reg;

	uint8_t reset_valued;
	uint8_t reserved_3[3];

	uint64_t x_firmware_control;
	uint64_t x_dsdt;

	struct generic_address x_pm1a_event_block;
	struct generic_address x_pm1b_event_block;
	struct generic_address x_pm1a_control_block;
	struct generic_address x_pm1b_control_block;
	struct generic_address x_pm2_control_block;
	struct generic_address x_pm_timer_block;
	struct generic_address x_gpe0_block;
	struct generic_address x_gpe1_block;
} __attribute__((packed));

struct xsdp *find_rsdp();
struct fadt *find_facp(struct xsdt *root_sdt);
void print_rsdp(const struct rsdp *rsdp);

static inline struct xsdt *get_rsdt(struct xsdp *rsdp) {
	if (rsdp == NULL || rsdp->revision == 0)
		return NULL;
	return (struct xsdt *) rsdp->xsdt_address;
}

#endif