// Copyright 2013 Dolphin Emulator Project / Citra Emulator Project
// Licensed under GPLv2
// Refer to the license.txt file included.

#pragma once

#include "common/common.h"

// ELF Header Constants

// File type
enum ElfType {
    ET_NONE = 0,
    ET_REL = 1,
    ET_EXEC = 2,
    ET_DYN = 3,
    ET_CORE = 4,
    ET_LOPROC = 0xFF00,
    ET_HIPROC = 0xFFFF,
};

// Machine/Architecture
enum ElfMachine {
    EM_NONE = 0,
    EM_M32 = 1,
    EM_SPARC = 2,
    EM_386 = 3,
    EM_68K = 4,
    EM_88K = 5,
    EM_860 = 7,
    EM_MIPS = 8
};

// File version
#define EV_NONE    0
#define EV_CURRENT 1

// Identification index
#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

// Magic number
#define ELFMAG0 0x7F
#define ELFMAG1  'E'
#define ELFMAG2  'L'
#define ELFMAG3  'F'

// File class
#define ELFCLASSNONE 0
#define ELFCLASS32   1
#define ELFCLASS64   2

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

// Sections constants

// Section indexes
#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

// Section types
#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

// Custom section types
#define SHT_PSPREL 0x700000a0

// Section flags
enum ElfSectionFlags
{
    SHF_WRITE = 0x1,
    SHF_ALLOC = 0x2,
    SHF_EXECINSTR = 0x4,
    SHF_MASKPROC = 0xF0000000,
};

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

// Symbol types
#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

// Undefined name
#define STN_UNDEF 0

// Relocation types
#define R_386_NONE      0
#define R_386_32        1
#define R_386_PC32      2
#define R_386_GOT32     3
#define R_386_PLT32     4
#define R_386_COPY      5
#define R_386_GLOB_DAT  6
#define R_386_JMP_SLOT  7
#define R_386_RELATIVE  8
#define R_386_GOTOFF    9
#define R_386_GOTPC    10

// Segment types
#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

// Segment flags
#define PF_X 1
#define PF_W 2
#define PF_R 4

// Dynamic Array Tags
#define DT_NULL              0
#define DT_NEEDED            1
#define DT_PLTRELSZ          2
#define DT_PLTGOT            3
#define DT_HASH              4
#define DT_STRTAB            5
#define DT_SYMTAB            6
#define DT_RELA              7
#define DT_RELASZ            8
#define DT_RELAENT           9
#define DT_STRSZ            10
#define DT_SYMENT           11
#define DT_INIT             12
#define DT_FINI             13
#define DT_SONAME           14
#define DT_RPATH            15
#define DT_SYMBOLIC         16
#define DT_REL              17
#define DT_RELSZ            18
#define DT_RELENT           19
#define DT_PLTREL           20
#define DT_DEBUG            21
#define DT_TEXTREL          22
#define DT_JMPREL           23
#define DT_LOPROC   0x70000000
#define DT_HIPROC   0x7FFFFFFF

typedef unsigned int  Elf32_Addr;
typedef unsigned short Elf32_Half;
typedef unsigned int  Elf32_Off;
typedef signed   int  Elf32_Sword;
typedef unsigned int  Elf32_Word;

// ELF file header
struct Elf32_Ehdr {
    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;
};

// Section header
struct Elf32_Shdr {
    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;
};

// Segment header
struct Elf32_Phdr {
    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;
};

// Symbol table entry
struct Elf32_Sym {
    Elf32_Word    st_name;
    Elf32_Addr    st_value;
    Elf32_Word    st_size;
    unsigned char st_info;
    unsigned char st_other;
    Elf32_Half    st_shndx;
};

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

// Relocation entries
struct Elf32_Rel {
    Elf32_Addr r_offset;
    Elf32_Word r_info;
};

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

#define ELF32_R_SYM(i) ((i)>>8)
#define ELF32_R_TYPE(i) ((unsigned char)(i))
#define ELF32_R_INFO(s,t) (((s)<<8 )+(unsigned char)(t))

struct Elf32_Dyn {
    Elf32_Sword d_tag;
    union {
        Elf32_Word d_val;
        Elf32_Addr d_ptr;
    } d_un;
};

enum KnownElfTypes {
    KNOWNELF_PSP = 0,
    KNOWNELF_DS = 1,
    KNOWNELF_GBA = 2,
    KNOWNELF_GC = 3,
};

typedef int SectionID;

class ElfReader {
private:
    char *base;
    u32 *base32;

    Elf32_Ehdr *header;
    Elf32_Phdr *segments;
    Elf32_Shdr *sections;

    u32 *sectionAddrs;
    bool bRelocate;
    u32 entryPoint;

public:
    ElfReader(void *ptr);
    ~ElfReader() { }

    u32 Read32(int off) const { return base32[off >> 2]; }

    // Quick accessors
    ElfType GetType() const { return (ElfType)(header->e_type); }
    ElfMachine GetMachine() const { return (ElfMachine)(header->e_machine); }
    u32 GetEntryPoint() const { return entryPoint; }
    u32 GetFlags() const { return (u32)(header->e_flags); }
    bool LoadInto(u32 vaddr);
    bool LoadSymbols();

    int GetNumSegments() const { return (int)(header->e_phnum); }
    int GetNumSections() const { return (int)(header->e_shnum); }
    const u8 *GetPtr(int offset) const { return (u8*)base + offset; }
    const char *GetSectionName(int section) const;
    const u8 *GetSectionDataPtr(int section) const {
        if (section < 0 || section >= header->e_shnum)
            return nullptr;
        if (sections[section].sh_type != SHT_NOBITS)
            return GetPtr(sections[section].sh_offset);
        else
            return nullptr;
    }
    bool IsCodeSection(int section) const {
        return sections[section].sh_type == SHT_PROGBITS;
    }
    const u8 *GetSegmentPtr(int segment) {
        return GetPtr(segments[segment].p_offset);
    }
    u32 GetSectionAddr(SectionID section) const { return sectionAddrs[section]; }
    int GetSectionSize(SectionID section) const { return sections[section].sh_size; }
    SectionID GetSectionByName(const char *name, int firstSection = 0) const; //-1 for not found

    bool DidRelocate() {
        return bRelocate;
    }
};

////////////////////////////////////////////////////////////////////////////////////////////////////
// Loader namespace

namespace Loader {

/**
 * Loads an ELF file
 * @param filename String filename of ELF file
 * @param error_string Pointer to string to put error message if an error has occurred
 * @return True on success, otherwise false
 */
bool Load_ELF(std::string& filename, std::string* error_string);

} // namespace Loader