#ifndef ELF_H
# define ELF_H 1

/* spec: https://refspecs.linuxfoundation.org/elf/elf.pdf
 *       elf(5)
 */
# include <stdint.h>

# define ELFMAG0 0x7F
# define ELFMAG1 0x45
# define ELFMAG2 0x4C
# define ELFMAG3 0x46

# define EI_MAG0    0
# define EI_MAG1    1
# define EI_MAG2    2
# define EI_MAG3    3
# define EI_CLASS   4
# define EI_DATA    5
# define EI_VERSION 6
# define EI_PAD     7
# define EI_NIDENT  16

# define ET_NONE   0
# define ET_REL    1
# define ET_EXEC   2
# define ET_DYN    3
# define ET_CORE   4
# define ET_LOPROC 0xFF00
# define ET_HIPROC 0xFFFF

# define EM_NONE        0
# define EM_M32         1
# define EM_SPARC       2
# define EM_386         3
# define EM_68K         4
# define EM_88K         5
# define EM_860         7
# define EM_MIPS        8
# define EM_MIPS_RS4_BE 10

# define EV_NONE    0
# define EV_CURRENT 1

# define ELFCLASSNONE 0
# define ELFCLASS32   1
# define ELFCLASS64   2

# define ELFDATANONE 0
# define ELFDATA2LSB 1
# define ELFDATA2MSB 2

typedef uint32_t Elf32_Addr;
typedef uint16_t Elf32_Half;
typedef uint32_t Elf32_Off;
typedef int32_t  Elf32_Sword;
typedef uint32_t Elf32_Word;

typedef struct {
	uint8_t    e_ident[EI_NIDENT];
	Elf32_Half e_type;
    Elf32_Half e_machine;
    Elf32_Word e_version;
	Elf32_Addr e_entry;
    Elf32_Off  e_phoff;
	Elf32_Off  e_shoff;
	Elf32_Word e_flags;
	Elf32_Half e_ehsize;
	Elf32_Half e_phentsize;
	Elf32_Half e_phnum;
	Elf32_Half e_shentsize;
	Elf32_Half e_shnum;
    Elf32_Half e_shstrndx;
} Elf32_Ehdr;

# define SHN_UNDEF     0
# define SHN_LORESERVE 0xFF00
# define SHN_LOPROC    0xFF00
# define SHN_HIPROC    0xFF1F
# define SHN_ABS       0xFFF1
# define SHN_COMMON    0xFFF2
# define SHN_HIRESERVE 0xFFFF

# define SHT_NULL     0
# define SHT_PROGBITS 1
# define SHT_SYMTAB   2
# define SHT_STRTAB   3
# define SHT_RELA     4
# define SHT_HASH     5
# define SHT_DYNAMIC  6
# define SHT_NOTE     7
# define SHT_NOBITS   8
# define SHT_REL      9
# define SHT_SHLIB    10
# define SHT_DYNSYM   11
# define SHT_LOPROC   0x70000000
# define SHT_HIPROC   0x7FFFFFFF
# define SHT_LOUSER   0x80000000
# define SHT_HIUSER   0xFFFFFFFF

# define SHF_WRITE     0x1
# define SHF_ALLOC     0x2
# define SHF_EXECINSTR 0x4
# define SHF_MASKPROC  0xF0000000

typedef struct {
	Elf32_Word sh_name;
	Elf32_Word sh_type;
	Elf32_Word sh_flags;
	Elf32_Addr sh_addr;
	Elf32_Off  sh_offset;
	Elf32_Word sh_size;
	Elf32_Word sh_link;
	Elf32_Word sh_info;
	Elf32_Word sh_addralign;
	Elf32_Word sh_entsize;
} Elf32_Shdr;

# define STN_UNDER 0

typedef struct {
    Elf32_Word st_name;
	Elf32_Addr st_value;
	Elf32_Word st_size;
	uint8_t    st_info;
	uint8_t    st_other;
	Elf32_Half st_shndx;
} Elf32_Sym;

# define ELF32_ST_BIND(x)    ((x)>>4)
# define ELF32_ST_TYPE(x)    ((x)&0xf)
# define ELF32_ST_INFO(b, t) (((b)<<4)+((t)&0xf))

# define STB_LOCAL   0
# define STB_GLOBAL  1
# define STB_WEAK    2
# define STB_LOPROC  13
# define STB_HIPROC  15

# define STT_NOTYPE  0
# define STT_OBJECT  1
# define STT_FUNC    2
# define STT_SECTION 3
# define STT_FILE    4
# define STT_LOPROC  13
# define STT_HIPROC  15

typedef struct {
	Elf32_Addr r_offset;
	Elf32_Word r_info;
} Elf32_Rel;

typedef struct {
	Elf32_Addr  r_offset;
	Elf32_Word  r_info;
	Elf32_Sword r_addend;
} Elf32_Rela;

# define ELF32_R_SYM(x)    ((x)>>8)
# define ELF32_R_TYPE(x)   ((uint8_t)(i));
# define ELF32_R_INFO(s,t) (((s)<<8)+(uint8_t)(t))

typedef struct {
	Elf32_Word p_type;
	Elf32_Off  p_offset;
	Elf32_Addr p_vaddr;
	Elf32_Addr p_paddr;
	Elf32_Word p_filesz;
	Elf32_Word p_memsz;
	Elf32_Word p_flags;
	Elf32_Word p_align;
} Elf32_Phdr;

# define PT_NULL    0
# define PT_LOAD    1
# define PT_DYNAMIC 2
# define PT_INTERP  3
# define PT_NOTE    4
# define PT_SHLIB   5
# define PT_PHDR    6
# define PT_LOPROC  0x70000000
# define PT_HIPROC  0x7FFFFFFF

# define PF_X        0x1
# define PF_W        0x2
# define PF_R        0x4
# define PF_MASKPROC 0xF0000000

#endif /* !ELF_H */