/* The ELF header resides at the beginning of an ELF file.
 * It identifies the file as an ELF file and contains the information
 * necessary for interpreting the contents of the file and locating
 * the other components of the file.
 * REF: https://gabi.xinuos.com/elf/02-eheader.html#elf-header
 */
#ifndef BFPG_ELF_HEADER_H
# define BFPG_ELF_HEADER_H

# include "eint.h"

# define EI_NIDENT (16)

typedef struct {
  unsigned char 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;

typedef struct {
  unsigned char e_ident[EI_NIDENT];
  Elf64_Half    e_type;
  Elf64_Half    e_machine;
  Elf64_Word    e_version;
  Elf64_Addr    e_entry;
  Elf64_Off     e_phoff;
  Elf64_Off     e_shoff;
  Elf64_Word    e_flags;
  Elf64_Half    e_ehsize;
  Elf64_Half    e_phentsize;
  Elf64_Half    e_phnum;
  Elf64_Half    e_shentsize;
  Elf64_Half    e_shnum;
  Elf64_Half    e_shstrndx;
} Elf64_Ehdr;

/* == ElfN_Ehdr.e_ident[] ==
 * EI_* macros define indexes into this this, and are followed
 * by a series a macros defining legal values for that index.
 */
/* XXX: WARNING: TODO :WARNING :XXX */
# define E_IDENT_DESC (                                                \
  "The initial bytes of an ELF file.\n\n"                              \
  "Marks the file as an object file and provides machine-independent " \
  "data with which to parse and interpret the file’s contents." )

/* == ElfN_Ehdr.e_type == */
enum e_type_t {
  ET_NONE   = 0,      /* No file type              */
  ET_REL    = 1,      /* Relocatable file          */
  ET_EXEC   = 2,      /* Executable file           */
  ET_DYN    = 3,      /* Shared object file        */
  ET_CORE   = 4,      /* Core file                 */
  ET_LOOS   = 0xfe00, /* OS-specific range start  */
  ET_HIOS   = 0xfeff, /* OS-specific range end    */
  ET_LOPROC = 0xff00, /* Processor-specific range start */
  ET_HIPROC = 0xffff, /* Processor-specific range end   */
};
# define E_TYPE_DESC (                                           \
  "Identifies the object file type.\n\n"                         \
  "ET_CORE is reserved and largely used by core files. "         \
  "However the actual file contents are left unspecified. "      \
  "Allowing projects to define their own extensions.\n\n"        \
  "Values ET_LOOS through ET_HIOS (inclusive) are reserved "     \
  "for OS-specific object file types.\n\n"                       \
  "Values ET_LOPROC through ET_HIPROC (inclusive) are reserved " \
  "for processor-specific object file types." )

/* == ElfN_Ehdr.e_machine == */
enum e_machine_t {
  /* XXX: WARNING: TODO :WARNING :XXX */
};
#define E_MACHINE_DESC ()

/* == ElfN_Ehdr.e_version == */
enum e_version_t {
  EV_NONE    = 0, /* Invalid version */
  EV_CURRENT = 1, /* Current Version */
};
#define E_VERSION_DESC (                            \
  "Version of ELF used.\n\n"                        \
  "EV_CURRENT signifies the original file format. " \
  "Extensions will use higher e_machine numbers" )

/* == ElfN_Ehdr.e_entry == */
#define E_ENTRY_DESC (                                                     \
  "Virtual address of the entry point.\n\n"                                \
  "The system first transfers control to this virtual address, "           \
  "thus starting the process. If the file has no associated entry point, " \
  "this member holds zero." )

#endif /* BFPG_ELF_HEADER_H */