#ifndef COMBOOT_H
#define COMBOOT_H

/**
 * @file
 *
 * SYSLINUX COMBOOT
 */

FILE_LICENCE ( GPL2_OR_LATER );

#include <stdint.h>
#include <setjmp.h>
#include <gpxe/in.h>

/** Descriptor in a 32-bit IDT */
struct idt_descriptor {
	uint16_t offset_low;
	uint16_t selector;
	uint16_t flags;
	uint16_t offset_high;
} __attribute__ (( packed ));

/** Operand for the LIDT instruction */
struct idt_register {
	uint16_t limit;
	uint32_t base;
} __attribute__ (( packed ));

/** Entry in the interrupt jump buffer */
struct ijb_entry {
	uint8_t pusha_instruction;
	uint8_t mov_instruction;
	uint8_t mov_value;
	uint8_t jump_instruction;
	uint32_t jump_destination;
} __attribute__ (( packed ));

/** The x86 opcode for "pushal" */
#define IJB_PUSHA 0x60

/** The x86 opcode for "movb $imm8,%al" */
#define IJB_MOV_AL_IMM8 0xB0

/** The x86 opcode for "jmp rel32" */
#define IJB_JMP_REL32 0xE9

/** Flags that specify a 32-bit interrupt gate with DPL=0 */
#define IDT_INTERRUPT_GATE_FLAGS 0x8E00

/** Address of COM32 interrupt descriptor table */
#define COM32_IDT 0x100000

/** Number of entries in a fully populated IDT */
#define COM32_NUM_IDT_ENTRIES 256

/** Address of COM32 interrupt jump buffer */
#define COM32_IJB 0x100800

/** Segment used for COMBOOT PSP and image */
#define COMBOOT_PSP_SEG 0x07C0

/** Entry point address of COM32 images */
#define COM32_START_PHYS 0x101000

/** COM32 bounce buffer segment */
#define COM32_BOUNCE_SEG 0x07C0

/** Size of SYSLINUX file block in bytes */
#define COMBOOT_FILE_BLOCKSZ 512

/** COMBOOT feature flags (INT 22h AX=15h) */
#define COMBOOT_FEATURE_LOCAL_BOOT (1 << 0)
#define COMBOOT_FEATURE_IDLE_LOOP  (1 << 1)

/** Maximum number of shuffle descriptors for 
 * shuffle and boot functions
 * (INT 22h AX=0012h, 001Ah, 001Bh)
 */
#define COMBOOT_MAX_SHUFFLE_DESCRIPTORS 682

typedef union {
	uint32_t l;
	uint16_t w[2];
	uint8_t  b[4];
} com32_reg32_t;

typedef struct {
	uint16_t gs;                /* Offset  0 */
	uint16_t fs;                /* Offset  2 */
	uint16_t es;                /* Offset  4 */
	uint16_t ds;                /* Offset  6 */

	com32_reg32_t edi;          /* Offset  8 */
	com32_reg32_t esi;          /* Offset 12 */
	com32_reg32_t ebp;          /* Offset 16 */
	com32_reg32_t _unused_esp;  /* Offset 20 */
	com32_reg32_t ebx;          /* Offset 24 */
	com32_reg32_t edx;          /* Offset 28 */
	com32_reg32_t ecx;          /* Offset 32 */
	com32_reg32_t eax;          /* Offset 36 */

	com32_reg32_t eflags;       /* Offset 40 */
} com32sys_t;

typedef struct {
	uint32_t eax;               /* Offset  0 */
	uint32_t ecx;               /* Offset  4 */
	uint32_t edx;               /* Offset  8 */
	uint32_t ebx;               /* Offset 12 */
	uint32_t esp;               /* Offset 16 */
	uint32_t ebp;               /* Offset 20 */
	uint32_t esi;               /* Offset 24 */
	uint32_t edi;               /* Offset 28 */

	uint32_t eip;               /* Offset 32 */
} syslinux_pm_regs;

typedef struct {
	uint16_t es;                /* Offset  0 */
	uint16_t _unused_cs;        /* Offset  2 */
	uint16_t ds;                /* Offset  4 */
	uint16_t ss;                /* Offset  6 */
	uint16_t fs;                /* Offset  8 */
	uint16_t gs;                /* Offset 10 */

	uint32_t eax;                /* Offset 12 */
	uint32_t ecx;                /* Offset 16 */
	uint32_t edx;                /* Offset 20 */
	uint32_t ebx;                /* Offset 24 */
	uint32_t esp;                /* Offset 28 */
	uint32_t ebp;                /* Offset 32 */
	uint32_t esi;                /* Offset 36 */
	uint32_t edi;                /* Offset 40 */

	uint16_t ip;                /* Offset 44 */
	uint16_t cs;                /* Offset 46 */
} syslinux_rm_regs;

typedef struct {
	uint32_t dest;
	uint32_t src;
	uint32_t len;
} comboot_shuffle_descriptor;

extern void hook_comboot_interrupts ( );
extern void unhook_comboot_interrupts ( );

/* These are not the correct prototypes, but it doens't matter, 
 * as we only ever get the address of these functions;
 * they are only called from COM32 code running in PHYS_CODE
 */
extern void com32_intcall_wrapper ( );
extern void com32_farcall_wrapper ( );
extern void com32_cfarcall_wrapper ( );
extern void com32_irq_wrapper ( );

/* Resolve a hostname to an (IPv4) address */
extern int comboot_resolv ( const char *name, struct in_addr *address );

/* setjmp/longjmp context buffer used to return after loading an image */
extern rmjmp_buf comboot_return;

/* Replacement image when exiting with COMBOOT_EXIT_RUN_KERNEL */
extern struct image *comboot_replacement_image;

extern void *com32_external_esp;

#define COMBOOT_EXIT 1
#define COMBOOT_EXIT_RUN_KERNEL 2
#define COMBOOT_EXIT_COMMAND 3

extern void comboot_force_text_mode ( void );

#define COMBOOT_VIDEO_GRAPHICS    0x01
#define COMBOOT_VIDEO_NONSTANDARD 0x02
#define COMBOOT_VIDEO_VESA        0x04
#define COMBOOT_VIDEO_NOTEXT      0x08

#endif