#ifndef ELF_H
#define ELF_H

/*
 * ELF handling
 * Valentin HAUDIQUET
 * Sources are :
 * - https://refspecs.linuxfoundation.org/elf/elf.pdf (ELF Reference)
 * - https://wiki.osdev.org/ELF (OSDev)
 */

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

typedef struct ELF_HEADER_32
{
	uint8_t ELF[4];
	uint8_t bits;       // 1 = 32bits, 2 = 64bits
	uint8_t endianness; // 1 = little, 2 = big
	uint8_t header_version;
	uint8_t abi;
	uint8_t padding0[8];
	uint16_t exec_type; // 1 = relocatable, 2 = executable, 3 = shared, 4 = core
	uint16_t instruction_set;
	uint32_t elf_version;
	uint32_t entry_32;
	uint32_t program_header_table_32;
	uint32_t section_table_32;
	uint32_t flags;
	uint16_t header_size;
	uint16_t program_entry_size;
	uint16_t program_entry_amount;
	uint16_t section_entry_size;
	uint16_t section_entry_amount;
	uint16_t section_str_index; // Index of string table associated with section names
} __attribute__((packed)) elf_header_32_t;

#define ELF_LITTLE_ENDIAN 1
#define ELF_BIG_ENDIAN 2

#define BITS_32 1
#define BITS_64 2

#define INSTRUCTION_SET_X86 0x3
#define INSTRUCTION_SET_X86_64 0x3E
#define INSTRUCTION_SET_RISCV 0xF3

typedef struct ELF_SECTION_HEADER_32
{
	uint16_t section_name;
	uint16_t section_type;
	uint16_t section_flags;
	uint32_t section_addr_32;
	uint32_t section_offset_32;
	uint16_t section_size;
	uint16_t section_link;
	uint16_t section_info;
	uint16_t section_addralign;
	uint16_t section_entrysize;
} __attribute__((packed)) elf_section_header_32_t;

typedef struct ELF_PROGRAM_HEADER_32
{
    uint32_t segment_type;
    uint32_t segment_offset;
    uint32_t virtual_address;
    uint32_t undefined;
    uint32_t segment_file_size;
    uint32_t segment_memory_size;
    uint32_t flags;
    uint32_t align;
} __attribute__((packed)) elf_program_header_32_t;

#define SEGMENT_TYPE_NULL 0
#define SEGMENT_TYPE_LOAD 1
#define SEGMENT_TYPE_DYNAMIC 2
#define SEGMENT_TYPE_INTERP 3
#define SEGMENT_TYPE_NOTE 4
#define SEGMENT_TYPE_RISCV_SPECIFIC_SHT_RISCV_ATTRIBUTES 0x70000003

uint32_t elf_32_load(void* file);

#endif