#!/usr/bin/env python3
import argparse, os, struct, ast, bisect

SPLIT_FILES = True # TODO this should be a flag somewhere

loadHighRefs = {}
loadLowRefs = {}

known_files = {}
known_funcs = dict()
known_objects = dict()
known_vars = dict()

regs = {
    0:"$zero", 1:"$at", 2:"$v0", 3:"$v1", 4:"$a0", 5:"$a1", 6:"$a2", 7:"$a3",
    8:"$t0", 9:"$t1", 10:"$t2", 11:"$t3", 12:"$t4", 13:"$t5", 14:"$t6", 15:"$t7",
    16:"$s0", 17:"$s1", 18:"$s2", 19:"$s3", 20:"$s4", 21:"$s5", 22:"$s6", 23:"$s7",
    24:"$t8", 25:"$t9", 26:"$k0", 27:"$k1", 28:"$gp", 29:"$sp", 30:"$fp", 31:"$ra",
    }

ops = {
    2:"j", 3:"jal", 4:"beq", 5:"bne", 6:"blez", 7:"bgtz",
    8:"addi", 9:"addiu", 10:"slti", 11:"sltiu", 12:"andi", 13:"ori", 14:"xori", 15:"lui",
    20:"beql", 21:"bnel", 22:"blezl", 23:"bgtzl",
    24:"daddi", 25:"daddiu",
    32:"lb", 33:"lh", 34:"lwl", 35:"lw", 36:"lbu", 37:"lhu", 38:"lwr",
    40:"sb", 41:"sh", 42:"swl", 43:"sw", 46:"swr", 47:"cache",
    48:"ll", 49:"lwc1", 50:"lwc2", 51:"pref", 53:"ldc1", 54:"ldc2", 55:"ld",
    56:"sc", 57:"swc1", 58:"swc2", 61:"sdc1", 62:"sdc2", 63:"sd",
    }

funcs = {
    0:"sll", 2:"srl", 3:"sra", 4:"sllv", 6:"srlv", 7:"srav",
    8:"jr", 9:"jalr", 10:"movz", 11:"movn", 12:"syscall", 13:"break", 15:"sync",
    16:"mfhi", 17:"mthi", 18:"mflo", 19:"mtlo", 20:"dsllv", 22:"dsrlv", 23:"dsrav",
    24:"mult", 25:"multu", 26:"div", 27:"divu", 28:"dmult", 29:"dmultu", 30:"ddiv", 31:"ddivu",
    32:"add", 33:"addu", 34:"sub", 35:"subu", 36:"and", 37:"or", 38:"xor", 39:"nor",
    42:"slt", 43:"sltu", 44:"dadd", 45:"daddu",
    48:"tge", 49:"tgeu", 50:"tlt", 51:"tltu", 52:"teq", 54:"tne",
    56:"dsll", 59:"dsra", 60:"dsll32", 63:"dsra32",
    }

branch1reg = {
    0:"bltz", 1:"bgez", 2:"bltzl", 3:"bgezl",
    8:"tgei", 9:"tgeiu", 10:"tlti", 11:"tltiu", 12:"tegi", 14:"tnei",
    16:"bltzal", 17:"bgezal", 18:"bltall", 19:"bgczall",
    }

floats = {
    0:"add", 1:"sub", 2:"mul", 3:"div", 4:"sqrt", 5:"abs", 6:"mov", 7:"neg",
    8:"round.l", 9:"trunc.l", 10:"ceil.l", 11:"floor.l", 12:"round.w", 13:"trunc.w", 14:"ceil.w", 15:"floor.w",
    18:"movz", 19:"movn",
    32:"cvt.s", 33:"cvt.d", 36:"cvt.w", 37:"cvt.l",
    48:"c.f", 49:"c.un", 50:"c.eq", 51:"c.ueq", 52:"c.olt", 53:"c.ult", 54:"c.ole", 55:"c.ule",
    56:"c.sf", 57:"c.ngle", 58:"c.seq", 59:"c.ngl", 60:"c.lt", 61:"c.nge", 62:"c.le", 63:"c.ngt",
    }

def read_file(name):
    file_data=[]

    try:
        with open(name, 'rb') as f:
            file_data = f.read()
    except IOError:
        print('failed to read file ' + name)
    return file_data


def float_reg(num):
    if num == 31:
        return "$31"
    return "$f%d" % num


def format_ref(name, offset):
    if offset == 0:
        return "{}".format(name)
    else:
        return "{} + 0x{:X}".format(name, offset)

def get_op(inst):
    return (inst & 0b11111100000000000000000000000000) >> 26


def get_func(inst):
    return (inst & 0b00000000000000000000000000111111)


def get_rs(inst):
    return (inst & 0b00000011111000000000000000000000) >> 21


def get_rt(inst):
    return (inst & 0b00000000000111110000000000000000) >> 16


def get_rd(inst):
    return (inst & 0b00000000000000001111100000000000) >> 11


def get_shift(inst):
    return (inst & 0b00000000000000000000011111000000) >> 6


def get_ft(inst):
    return (inst & 0b00000000000111110000000000000000) >> 16


def get_fs(inst):
    return (inst & 0b00000000000000001111100000000000) >> 11


def get_fd(inst):
    return (inst & 0b00000000000000000000011111000000) >> 6


def get_imm(inst):
    return inst & 0b00000000000000001111111111111111


def get_signed_imm(inst):
    imm = get_imm(inst)
    if (imm & (1 << 15)) != 0:
        imm = -2**15 + (imm & 0b00000000000000000111111111111111)
    return imm


def is_load(inst):
    return get_op(inst) > 31


def get_func_name(addr):
    if addr in known_funcs:
        return known_funcs[addr][0]
    else:
        return "func_%08X" % addr


def get_symbol_name(addr):
    if addr in known_vars and known_vars[addr][0] != "":
        return known_vars[addr][0]
    else:
        return "D_%08X" % addr


def write_header(file):
    file.write(".set noat # allow use of $at\n"
               ".set noreorder # don't insert nops after branches\n"
               ".set gp=64 # allow use of 64bit registers\n"
               ".macro glabel label\n"
               "    .global \label\n"
               "    \label:\n"
               ".endm\n"
               "\n")


# TODO add code_regions?
class Disassembler:

    class File:
        def __init__(self, name, data, vaddr):
            self.name = name
            self.data = data
            self.vaddr = vaddr
            self.size = len(data)

        def get_inst(self, num):
            offset = num*4
            return struct.unpack('>I', self.data[offset:offset+4])[0]

    def __init__(self):
        self.files = list()
        self.objects = set()
        self.functions = set()
        self.labels = set()
        self.vars = set()
        self.switch_cases = set()
        self.vars_sorted = list()
        self.vars_length = dict()
        self.data_regions = list()
        self.bss_regions = list()

        self.has_done_first_pass = False

        self.auto_analysis = False

        self.is_data_cache = {}
        self.is_code_cache = {}
        self.is_bss_cache = {}

    def load_defaults(self):
        for file in known_files:
            self.add_file(file[0], file[1], file[2])
            self.add_object(file[2]) # assume every file starts with a object and function
            self.add_function(file[2])
            for region in file[3]:
                self.add_data_region(region[0], region[1], file[1])
            for region in file[4]:
                self.add_bss_region(region[0], region[1], file[1])

        for addr in known_funcs:
            self.add_function(addr)

        for addr in known_objects:
            self.add_object(addr)
            if self.is_in_code(addr):
                self.add_function(addr) # assume every object starts with a function

        for addr in known_vars:
            self.add_variable(addr, known_vars[addr][3])

    def reset_cache(self):
        self.is_data_cache = {}
        self.is_code_cache = {}
        self.is_bss_cache = {}

    def add_file(self, path, name, vaddr):
        self.files.append(self.File(name, read_file(path + '/' + name), vaddr))
        self.files = sorted(self.files, key = lambda file: file.vaddr)
        self.reset_cache()

    def add_object(self, addr):
        self.objects.add(addr)

    def add_function(self, addr):
        self.functions.add(addr)

    def add_variable(self, addr, size):
        # TODO special case this value that is mis-identified as an address and causes problems by being in the middle of a pointer
        if addr == 0x80AAB3AE:
            return
        self.vars.add(addr)
        bisect.insort(self.vars_sorted, addr)
        self.vars_length[addr] = size

    def add_label(self, addr):
        self.labels.add(addr)

    def add_data_region(self, start, end, file_name):
        self.data_regions.append((start, end, file_name))
        self.data_regions = sorted(self.data_regions, key = lambda region: region[0])
        self.reset_cache()

    def add_bss_region(self, start, end, file_name):
        self.bss_regions.append((start, end, file_name))
        self.bss_regions = sorted(self.bss_regions, key = lambda region: region[0])
        self.reset_cache()

    def set_auto_analysis(self, setting):
        self.auto_analysis = setting

    def is_in_data(self, addr):
        if addr in self.is_data_cache:
            return self.is_data_cache[addr]

        start = 0
        last = len(self.data_regions) - 1
        while start <= last:
            midpoint = (start + last) // 2
            if addr >= self.data_regions[midpoint][0]:
                if addr <= self.data_regions[midpoint][1]:
                    self.is_data_cache[addr] = True
                    return True
                else:
                    start = midpoint + 1
            else:
                last = midpoint - 1

        self.is_data_cache[addr] = False
        return False

    def is_in_code(self, addr):
        if addr in self.is_code_cache:
            return self.is_code_cache[addr]

        start = 0
        last = len(self.files) - 1
        while start <= last:
            midpoint = (start + last) // 2
            if addr >= self.files[midpoint].vaddr:
                if addr < (self.files[midpoint].vaddr + self.files[midpoint].size):
                    self.is_code_cache[addr] = not self.is_in_data(addr)
                    return self.is_code_cache[addr]
                else:
                    start = midpoint + 1
            else:
                last = midpoint - 1

        self.is_code_cache[addr] = False
        return False

    def is_in_bss(self, addr):
        if addr in self.is_bss_cache:
            return self.is_bss_cache[addr]

        start = 0
        last = len(self.bss_regions) - 1
        while start <= last:
            midpoint = (start + last) // 2
            if addr >= self.bss_regions[midpoint][0]:
                if addr <= self.bss_regions[midpoint][1]:
                    self.is_bss_cache[addr] = True
                    return True, self.bss_regions[midpoint]
                else:
                    start = midpoint + 1
            else:
                last = midpoint - 1

        self.is_bss_cache[addr] = False
        return False, None

    def is_in_data_or_undef(self, addr):
        # return true if it is in a defined data region
        if self.is_in_data(addr):
            return True

        # otherwise return false if it is in a file's bounds
        if self.is_in_code(addr):
            return False

        # otherwise it is undefined (return true)
        return True

    def is_start_of_variable(self, addr):
        return addr in self.vars

    def get_variable_offset(self, addr):
        if len(self.vars_sorted) == 0:
            return None
        if self.is_start_of_variable(addr):
            return (addr, 0)
        nearest = self.vars_sorted[bisect.bisect_left(self.vars_sorted, addr)-1]
        offset = addr - nearest
        if offset < self.vars_length[nearest]:
            return (nearest, offset)
        return None

    def make_label(self, imm, cur):
        addr = (imm*4) + cur + 4
        self.add_label(addr)
        return ".L_%08X" % addr

    def make_func(self, imm, cur):
        addr = (imm*4) + (cur & 0xF0000000)
        self.add_function(addr)
        return get_func_name(addr)

    def make_load(self, addr):
        if self.is_in_data_or_undef(addr):
            return get_symbol_name(addr)
        else:
            return get_func_name(addr)

    # TODO refactor to remove file_addr
    def get_object_name(self, addr, file_addr):
        filename = ""

        for file in self.files:
            if file_addr == file.vaddr:
                filename = file.name

        if filename == "":
            print("Bad file_addr passed to get_object_name: 0x%0X" % addr)
            return

        if SPLIT_FILES:
            if addr in known_objects and known_objects[addr] != "": # no name means object boundary is known but not the name
                return known_objects[addr]
            else:
                return '%s_0x%08X' % (filename, addr)
        else:
            return "%s" % filename

    def guess_functions_and_variables_from_data(self):
        for file in self.files:
            for i in range(0, file.size // 4):
                word = file.get_inst(i)
                addr = file.vaddr + i*4
                if self.is_in_data(addr):
                    if self.is_in_code(word) and (word % 4) == 0:
                        None
                        # TODO functions are disabled for now due to behaving poorly with switches. This should be a flag.
                        #self.add_function(word)
                    elif self.is_in_data(word):
                        self.add_variable(word, 1)


    def disassemble(self, path):
        self.first_pass()
        self.second_pass(path)

    def first_pass(self):
        if self.has_done_first_pass == True:
            return

        for file in self.files:
            for i in range(0, file.size // 4):
                inst = file.get_inst(i)
                addr = file.vaddr + i*4
                if not self.is_in_data_or_undef(addr):
                    self.disassemble_inst(inst, addr, i, file)

                    if inst == 0x03E00008 and self.auto_analysis: # jr $ra
                        next_index = i+2
                        if file.get_inst(next_index) == 0: # nop
                            while file.get_inst(next_index) == 0:
                                next_index += 1

                            new_object_start = file.vaddr + next_index*4 + 15
                            new_object_start -= new_object_start % 16

                            # don't split if it's the start of a data section, it's probably the same object
                            if not self.is_in_data_or_undef(new_object_start):
                                self.add_object(new_object_start)
                if addr in self.vars:
                    name = self.make_load(addr)
                    if name.startswith("__switch"):
                        addr_i = i
                        case_addr = file.get_inst(addr_i)
                        while self.is_in_code(case_addr):
                            self.switch_cases.add(case_addr)
                            addr_i += 1
                            if addr_i >= (file.size // 4):
                                break
                            case_addr = file.get_inst(addr_i)
        if self.auto_analysis:
            self.guess_functions_and_variables_from_data()
        self.has_done_first_pass = True

    def second_pass(self, path):
        for file in self.files:
            filename = path + '/%s.asm' % self.get_object_name(file.vaddr, file.vaddr)

            with open(filename, 'w') as f:
                write_header(f)

                for i in range(0, file.size // 4):
                    inst = file.get_inst(i)
                    addr = file.vaddr + i*4

                    if addr in self.objects and SPLIT_FILES:
                        f.close()
                        filename = path + '/%s.asm' % self.get_object_name(addr, file.vaddr)
                        f = open(filename, 'w')
                        write_header(f)

                    if addr in self.labels and addr not in self.switch_cases:
                        f.write(".L_%08X:\n" % addr)
                    if addr in self.switch_cases:
                        f.write("glabel .L_%08X\n" % addr)
                    if addr in self.functions:
                        name = get_func_name(addr)
                        f.write("\nglabel %s\n" % name)

                    if not self.is_in_data_or_undef(addr):
                        f.write("/* %06d 0x%08X %08X */ %s\n" % (i, addr, inst, self.disassemble_inst(inst, addr, i, file)))
                    elif inst in self.functions:
                        if self.is_start_of_variable(addr):
                            name = self.make_load(addr)
                            f.write("glabel %s\n" % name)
                        f.write("/* %06d 0x%08X */ .word\t%s\n" % (i, addr, get_func_name(inst)))
                    elif inst in self.switch_cases:
                        if self.is_start_of_variable(addr):
                            name = self.make_load(addr)
                            f.write("glabel %s\n" % name)
                        f.write("/* %06d 0x%08X */ .word\t.L_%08X\n" % (i, addr, inst))
                    elif self.is_start_of_variable(inst):
                        if self.is_start_of_variable(addr):
                            name = self.make_load(addr)
                            f.write("glabel %s\n" % name)
                        f.write("/* %06d 0x%08X */ .word\t%s\n" % (i, addr, self.make_load(inst)))
                    elif inst >= 0x801F0568 and inst < 0x801F0684:
                        # XXX special case gSaveContext.weekEventReg because there are pointers to fields of it in other parts of dara
                        # TODO think of a better way to do this
                        if self.is_start_of_variable(addr):
                            name = self.make_load(addr)
                            f.write("glabel %s\n" % name)
                        var = self.get_variable_offset(inst)
                        f.write("/* %06d 0x%08X */ .word\t(%s + 0x%08X)\n" % (i, addr, self.make_load(var[0]), var[1]))
                    else:
                        # TODO this should be moved into a print_data_range function or something
                        print_head = addr
                        data_stream = inst
                        while print_head < addr + 4:
                            if self.is_start_of_variable(print_head):
                                name = self.make_load(print_head)
                                f.write("glabel %s\n" % name)
                            if self.is_start_of_variable(print_head+1) or print_head % 2 != 0:
                                f.write("/* %06d 0x%08X */ .byte\t0x%02X\n" % (i, addr, (data_stream >> 24) & 0xFF))
                                data_stream <<= 8
                                print_head += 1
                            elif self.is_start_of_variable(print_head+2) or self.is_start_of_variable(print_head+3) or print_head % 4 != 0:
                                f.write("/* %06d 0x%08X */ .short\t0x%04X\n" % (i, addr, (data_stream >> 16) & 0xFFFF))
                                data_stream <<= 16
                                print_head += 2
                            else:
                                f.write("/* %06d 0x%08X */ .word\t0x%08X\n" % (i, addr, data_stream & 0xFFFFFFFF))
                                data_stream <<= 32
                                print_head += 4

    def determine_load_ref_impl(self, file, inst_i, start_i, depth, from_branch=False, visited=set()):
        candidates = []

        if not from_branch:
            visited.clear()

        # debug_i = 5217
        debug_i = 0xFFFFFFFF

        if inst_i == debug_i:
            print("{} {} {}".format(inst_i, start_i, from_branch))

        if depth <= 0:
            return candidates
        # TODO better detect when the register gets dirty
        cur_inst = file.get_inst(inst_i)

        addr_high = get_imm(cur_inst)
        if (addr_high > 0x80C2) or (addr_high < 0x8000):
            return candidates

        if get_op(cur_inst) != 15:
            return candidates

        # set state based on previous instruction
        # TODO cleanup
        if start_i == 0 or from_branch:
            prev_was_jump = False
            prev_was_ret = False
            prev_was_branch = False
            prev_was_branch_f = False
            prev_was_branch_f_likely = False
            prev_was_branch_likely = False
            prev_was_branch_always = False
            prev_target = 0
        else:
            prev_inst = file.get_inst(start_i - 1)
            prev_op = get_op(prev_inst)
            prev_was_jump = (prev_op == 2 or prev_op == 3)
            prev_was_ret = (prev_op == 0 and get_func(prev_inst) == 8)
            prev_was_branch = (prev_op == 4 or prev_op == 5 or prev_op == 6 or prev_op == 7) or \
                              (prev_op == 1 and (get_rt(prev_inst) == 0 or get_rt(prev_inst) == 1))
            prev_was_branch_f = ((prev_op == 16) or (prev_op == 17) or (prev_op == 18)) and (get_rs(prev_inst) == 8) and ((prev_inst & (1 << 17)) == 0)
            prev_was_branch_f_likely = ((prev_op == 16) or (prev_op == 17) or (prev_op == 18)) and (get_rs(prev_inst) == 8) and ((prev_inst & (1 << 17)) != 0)
            prev_was_branch_always = prev_op == 4 and get_rs(prev_inst) == get_rt(prev_inst) == 0
            prev_was_branch_likely = (prev_op == 20 or prev_op == 21 or prev_op == 22 or prev_op == 23) or \
                                     (prev_op == 1 and (get_rt(prev_inst) == 2 or get_rt(prev_inst) == 3))
            prev_target = get_signed_imm(prev_inst) * 4 + (file.vaddr + (start_i-1)*4) + 4

            if prev_was_branch or prev_was_branch_f or prev_was_branch_likely or prev_was_branch_f_likely:
                if inst_i == debug_i:
                    print("branch start")
                branch_candidates = self.determine_load_ref_impl(file, inst_i, (prev_target - file.vaddr) // 4, depth, True, visited)
                candidates += branch_candidates
                if inst_i == debug_i:
                    print("branch end, found {}".format(branch_candidates))


        continue_branch = not (prev_was_branch_likely or prev_was_branch_f_likely)

        prev_was_jump = False
        prev_was_ret = False
        prev_was_branch = False
        prev_was_branch_f = False
        prev_was_branch_f_likely = False
        prev_was_branch_likely = False
        prev_was_branch_always = False
        prev_target = 0

        inst_read_addr = start_i if from_branch else start_i + 1

        for i in range(1, depth + 1):
            if not continue_branch:
                break

            if inst_read_addr in visited:
                break

            if inst_i == debug_i:
                print(" {}".format(inst_read_addr))

            if self.is_in_data(file.vaddr + inst_read_addr*4):
                break

            next_inst = file.get_inst(inst_read_addr)
            next_op = get_op(next_inst)
            next_func = get_func(next_inst)

            # TODO consolidate
            if (next_op == 9) and (get_rt(cur_inst) == get_rs(next_inst)): # lui + addiu (move pointer)
                addr = (get_imm(cur_inst) << 16) + get_signed_imm(next_inst)

                # TODO workaround to avoid classifying loading constants as loading pointers
                # This unfortunately causes it to not detect object addresses
                if addr > 0x80000000:
                    var = self.get_variable_offset(addr)

                    if var == None:
                        if self.auto_analysis:
                            if self.is_in_data_or_undef(addr):
                                self.add_variable(addr, 1)
                                var = (addr, 0)
                            else:
                                self.add_function(addr)
                                var = (addr, 0)
                        elif addr in self.functions:
                            var = (addr, 0)

                    if var != None:
                        candidates.append((file.vaddr + inst_read_addr*4, var[0], var[1]))

                if get_rt(cur_inst) == get_rt(next_inst):
                    if prev_was_branch_likely or prev_was_branch_f_likely:
                        prev_was_branch_likely = False
                        prev_was_branch_f_likely = False
                    else:
                        prev_was_branch = False
                        prev_was_branch_f = False
                        prev_was_branch_always = False
                        continue_branch = False

            elif is_load(next_inst) and (get_rt(cur_inst) == get_rs(next_inst)): # lui + load (load pointer)
                addr = (get_imm(cur_inst) << 16) + get_signed_imm(next_inst)

                # TODO workaround to avoid classifying loading constants as loading pointers
                # This unfortunately causes it to not detect object addresses
                if addr > 0x80000000:
                    var = self.get_variable_offset(addr)

                    if var == None:
                        if self.auto_analysis:
                            if self.is_in_data_or_undef(addr):
                                self.add_variable(addr, 1)
                                var = (addr, 0)
                            else:
                                print("Warning: Pointer load location is in code 0x%08X @ 0x%08X, base=0x%08X" % (addr, file.vaddr + inst_read_addr*4, file.vaddr + inst_i*4))
                                self.add_function(addr)
                                var = (addr, 0)
                        elif addr in self.functions:
                            var = (addr, 0)

                    if var != None:
                        candidates.append((file.vaddr + inst_read_addr*4, var[0], var[1]))

                if get_rt(cur_inst) == get_rt(next_inst):
                    if prev_was_branch_likely or prev_was_branch_f_likely:
                        prev_was_branch_likely = False
                        prev_was_branch_f_likely = False
                    else:
                        prev_was_branch = False
                        prev_was_branch_f = False
                        prev_was_branch_always = False
                        continue_branch = False

            elif ((next_op >= 32) and (next_op < 48)) and (get_rt(cur_inst) == get_rt(next_inst)): # load that overwrites the reg () exclude fp loads
                if prev_was_branch_likely or prev_was_branch_f_likely:
                    prev_was_branch_likely = False
                    prev_was_branch_f_likely = False
                else:
                    prev_was_branch = False
                    prev_was_branch_f = False
                    prev_was_branch_always = False
                    continue_branch = False

            elif ((next_op == 8) or (next_op == 9) or (next_op == 15)) and \
                 (get_rt(cur_inst) == get_rt(next_inst)):
                if prev_was_branch_likely or prev_was_branch_f_likely:
                    prev_was_branch_likely = False
                    prev_was_branch_f_likely = False
                else:
                    prev_was_branch = False
                    prev_was_branch_f = False
                    prev_was_branch_always = False
                    continue_branch = False

            # TODO more funcs?
            elif next_op == 0 and \
                 ((next_func == 0) or (next_func == 2) or (next_func == 3) or \
                  (next_func == 24) or (next_func == 25) or (next_func == 26) or (next_func == 27) or \
                  (next_func == 32) or (next_func == 33) or (next_func == 34) or (next_func == 35) or \
                  (next_func == 36) or (next_func == 37) or (next_func == 38) or (next_func == 39) or \
                  (next_func == 42) or (next_func == 43)) and \
                 (get_rt(cur_inst) == get_rd(next_inst) and \
                 (get_rt(cur_inst) != get_rt(next_inst)) and (get_rt(cur_inst) != get_rs(next_inst))):
                if prev_was_branch_likely or prev_was_branch_f_likely:
                    prev_was_branch_likely = False
                    prev_was_branch_f_likely = False
                else:
                    prev_was_branch = False
                    prev_was_branch_f = False
                    prev_was_branch_always = False
                    continue_branch = False

            visited.add(inst_read_addr)

            if prev_was_branch or prev_was_branch_f or prev_was_branch_likely or prev_was_branch_f_likely:
                if inst_i == debug_i:
                    print("branch start")
                branch_candidates = self.determine_load_ref_impl(file, inst_i, (prev_target - file.vaddr) // 4, depth-i, True, visited)
                candidates += branch_candidates
                if inst_i == debug_i:
                    print("branch end, found {}".format(branch_candidates))

            # if this is a jump, mark to return after we evaluate the following instruction
            if prev_was_jump or prev_was_ret:
                continue_branch = False

            if prev_was_branch_always:
                continue_branch = False

            prev_was_jump = (next_op == 2 or next_op == 3)
            prev_was_ret = (next_op == 0 and get_func(next_inst) == 8)
            prev_was_branch = (next_op == 4 or next_op == 5 or next_op == 6 or next_op == 7) or \
                              (next_op == 1 and (get_rt(next_inst) == 0 or get_rt(next_inst) == 1))
            prev_was_branch_f = ((next_op == 16) or (next_op == 17) or (next_op == 18)) and (get_rs(next_inst) == 8) and ((next_inst & (1 << 17)) == 0)
            prev_was_branch_f_likely = ((next_op == 16) or (next_op == 17) or (next_op == 18)) and (get_rs(next_inst) == 8) and ((next_inst & (1 << 17)) != 0)
            prev_was_branch_always = next_op == 4 and get_rs(next_inst) == get_rt(next_inst) == 0
            prev_was_branch_likely = (next_op == 20 or next_op == 21 or next_op == 22 or next_op == 23) or \
                                     (next_op == 1 and (get_rt(next_inst) == 2 or get_rt(next_inst) == 3))
            prev_target = get_signed_imm(next_inst)*4 + (file.vaddr + inst_read_addr*4) + 4

            inst_read_addr += 1

        return candidates

    def determine_load_ref(self, file, inst_i):
        candidates = self.determine_load_ref_impl(file, inst_i, inst_i, 200)
        if len(candidates) > 0:
            first = candidates[0] # TODO multiple candidates
            loadHighRefs[file.vaddr + inst_i*4] = (first[1], first[2])
            loadLowRefs[first[0]] = (first[1], first[2])
            for condidate in candidates[1:]:
                loadLowRefs[condidate[0]] = (condidate[1], condidate[2])

    def disassemble_inst(self, inst, addr, i, file):
        if inst == 0:
            return "nop"

        dis = ""
        op_num = get_op(inst)

        if op_num == 0:
            func = get_func(inst)
            if func == 1:
                cc = (inst & (7 << 18)) >> 18
                if (inst & (1 << 16)) == 0:
                    dis += "movf\t%s, %s, %d" % (regs[get_rd(inst)], regs[get_rs(inst)], cc)
                else:
                    dis += "movt\t%s, %s, %d" % (regs[get_rd(inst)], regs[get_rs(inst)], cc)
            else:
                if func not in funcs:
                    dis += "func_error: %d" % func
                else:
                    if func == 37 and get_rt(inst) == 0: # or with zero reg is move
                        return "move\t%s, %s" % (regs[get_rd(inst)], regs[get_rs(inst)])
                    dis += "%s\t" % funcs[func]
                    if func == 0 or func == 2 or func == 3 or func == 56 or func == 59 or func == 60 or func == 63: # sll, srl, sra, dsll, dsra dsll32, dsra32
                        dis += "%s, %s, %d" % (regs[get_rd(inst)], regs[get_rt(inst)], get_shift(inst))
                    elif func == 4 or func == 6 or func == 7: # sllv, srlv, srav
                        dis += "%s, %s, %s" % (regs[get_rd(inst)], regs[get_rt(inst)], regs[get_rs(inst)])
                    elif func == 8 or func == 9: # jr, jalr
                        dis += "%s" % regs[get_rs(inst)]
                    elif func == 13: # break
                        dis += "0x%05X" % ((inst & (0xFFFFF << 6)) >> 16) # TODO the error code is 20 bits in the manual, why does gas want something else?
                    elif func == 16 or func == 18: # mfhi, mflo
                        dis += "%s" % regs[get_rd(inst)]
                    elif func == 17 or func == 19: # mthi, mtlo
                        dis += "%s" % regs[get_rs(inst)]
                    elif func == 24 or func == 25 or func == 28 or func == 29: # mult, multu, dmult, dmultu
                        dis += "%s, %s" % (regs[get_rs(inst)], regs[get_rt(inst)])
                    elif func == 26 or func == 27 or func == 30 or func == 31: # div, divu, ddiv, ddivu
                        dis += "$zero, %s, %s" % (regs[get_rs(inst)], regs[get_rt(inst)]) # TODO why does this need $zero for gas to not think it's a macro?
                    elif func == 34 and get_rs(inst) == 0: # sub with $zero is neg
                        dis = "neg\t%s, %s" % (regs[get_rd(inst)], regs[get_rt(inst)])
                    elif func == 35 and get_rs(inst) == 0: # subu with $zero is negu
                        dis = "negu\t%s, %s" % (regs[get_rd(inst)], regs[get_rt(inst)])
                    elif func == 20 or func == 22 or func == 23: # doubleword ops
                        dis += "%s, %s, %s" % (regs[get_rd(inst)], regs[get_rt(inst)], regs[get_rs(inst)])
                    else: # add, sub, logical, etc.
                        dis += "%s, %s, %s" % (regs[get_rd(inst)], regs[get_rs(inst)], regs[get_rt(inst)])
                    # TODO traps

        elif op_num == 1:
            rt = get_rt(inst)
            if rt not in branch1reg:
                dis += "branch1reg_erro: %d" % rt
            else:
                # TODO traps
                dis += "%s\t%s, %s" % (branch1reg[rt], regs[get_rs(inst)], self.make_label(get_signed_imm(inst), addr))

        elif op_num == 16 or op_num == 17 or op_num == 18:
            z = op_num - 16
            rs = get_rs(inst)
            if rs == 0:
                dis += "mfc%d\t%s, %s" % (z, regs[get_rt(inst)], float_reg(get_rd(inst)) if z != 0 else "$%d" % get_rd(inst))
            elif rs == 1:
                dis += "dmfc%d\t%s, %s" % (z, regs[get_rt(inst)], float_reg(get_rd(inst)) if z != 0 else "$%d" % get_rd(inst))
            elif rs == 2:
                dis += "cfc%d\t%s, %s" % (z, regs[get_rt(inst)], float_reg(get_rd(inst)) if z != 0 else "$%d" % get_rd(inst))
            elif rs == 4:
                dis += "mtc%d\t%s, %s" % (z, regs[get_rt(inst)], float_reg(get_rd(inst)) if z != 0 else "$%d" % get_rd(inst))
            elif rs == 5:
                dis += "dmtc%d\t%s, %s" % (z, regs[get_rt(inst)], float_reg(get_rd(inst)) if z != 0 else "$%d" % get_rd(inst))
            elif rs == 6:
                dis += "ctc%d\t%s, %s" % (z, regs[get_rt(inst)], float_reg(get_rd(inst)) if z != 0 else "$%d" % get_rd(inst))
            elif rs == 8:
                dis += "bc%d%s%s %s" % (z, "f" if ((inst & (1 << 16)) == 0) else "t", "" if ((inst & (1 << 17)) == 0) else "l", self.make_label(get_signed_imm(inst), addr))
            elif rs == 16 or rs == 17 or rs == 20 or rs == 21:
                if z == 0:
                    func = get_func(inst)
                    if func == 1:
                        dis += "tlbr"
                    elif func == 2:
                        dis += "tlbwi"
                    elif func == 6:
                        dis += "tlbwr"
                    elif func == 8:
                        dis += "tlbp"
                    elif func == 24:
                        dis += "eret"
                    else:
                        # TODO deret?
                        dis += "cop0_error: %d" % func
                elif z != 1:
                    dis += "cop_error: %d" % z
                else:
                    if rs == 16:
                        f = "s"
                    elif rs == 17:
                        f = "d"
                    elif rs == 20:
                        f = "w"
                    elif rs == 21:
                        f = "l"
                    func = get_func(inst)
                    if func not in floats:
                        dis += "float_error: %d" % func
                    else:
                        dis += "%s.%s\t" % (floats[func], f)
                        if func == 0 or func == 1 or func == 2 or func == 3 or func == 18 or func == 19: # 3 op
                            dis += "%s, %s, %s" % (float_reg(get_fd(inst)), float_reg(get_fs(inst)), float_reg(get_ft(inst)))
                        elif (func == 4 or func == 5 or func == 6 or func == 7 or func == 8 or func == 9  or func == 10 or func == 11 or func == 12
                              or func == 13 or func == 14 or func == 15 or func == 32 or func == 33 or func == 36 or func == 37): # 2 op
                            dis += "%s, %s" % (float_reg(get_fd(inst)), float_reg(get_fs(inst)))
                        elif func == 50 or func == 60 or func == 62: # c.eq, c.lt, c.le
                            dis += "%s, %s" % (float_reg(get_fs(inst)), float_reg(get_ft(inst)))
            else:
                dis += "coproc_error: %d" % rs

        elif op_num not in ops:
            dis += "error: %d" % op_num

        else:
            dis += "%s\t" % ops[op_num]
            if op_num == 2 or op_num == 3: # j, jal
                dis += "%s" % self.make_func(inst & 0x3FFFFFF, addr)
            elif op_num == 4 or op_num == 5 or op_num == 20 or op_num == 21: # beq, bne, beql, bnel
                if op_num == 4 and get_rs(inst) == get_rt(inst) == 0: # beq with both zero regs is a branch always (b %label)
                    dis = "b\t%s" % self.make_label(get_signed_imm(inst), addr)
                else:
                    if get_rt(inst) == 0: # branchs comparing to 0 have a shorthand
                        dis = "%s\t" % ("beqz" if op_num == 4 else "bnez" if op_num == 5 else "beqzl" if op_num == 20 else "bnezl")
                        dis += "%s, %s" % (regs[get_rs(inst)], self.make_label(get_signed_imm(inst), addr))
                    else:
                        dis += "%s, %s, %s" % (regs[get_rs(inst)], regs[get_rt(inst)], self.make_label(get_signed_imm(inst), addr))
            elif op_num == 6 or op_num == 7 or op_num == 22 or op_num == 23: # blez, bgtz, blezl, bgtzl
                dis += "%s, %s" % (regs[get_rs(inst)], self.make_label(get_signed_imm(inst), addr))
            elif op_num == 8 or op_num == 9 or op_num == 10 or op_num == 11 or op_num == 24 or op_num == 25: # addi, addiu, slti, sltiu, daddi, daddiu
                if op_num == 9 and get_rs(inst) == 0: # addiu with reg 0 is load immediate (li)
                    dis = "li\t%s, %d" % (regs[get_rt(inst)], get_signed_imm(inst))
                elif op_num == 9 and addr in loadLowRefs: # addiu loading the lower half of a pointer
                    ref = loadLowRefs[addr]
                    dis += "%s, %s, %%lo(%s)" % (regs[get_rt(inst)], regs[get_rs(inst)], format_ref(self.make_load(ref[0]), ref[1]))
                else:
                    dis += "%s, %s, %d" % (regs[get_rt(inst)], regs[get_rs(inst)], get_signed_imm(inst))
            elif op_num == 12 or op_num == 13 or op_num == 14: # andi, ori, xori
                dis += "%s, %s, %#X" % (regs[get_rt(inst)], regs[get_rs(inst)], get_imm(inst))
            elif op_num == 15: # lui
                if not self.has_done_first_pass:
                    self.determine_load_ref(file, i)
                if addr in loadHighRefs: # lui loading the higher half of a pointer
                    ref = loadHighRefs[addr]
                    dis += "%s, %%hi(%s)" % (regs[get_rt(inst)], format_ref(self.make_load(ref[0]), ref[1]))
                else:
                    dis += "%s, 0x%04X" % (regs[get_rt(inst)], get_imm(inst))
            elif (op_num == 32 or op_num == 33 or op_num == 34 or op_num == 35 or op_num == 38 or op_num == 40 or op_num == 41 or
                 op_num == 42 or op_num == 42 or op_num == 43 or op_num == 46 or op_num == 55 or op_num == 63): # load/stores
                if addr in loadLowRefs: # loading with immediate forming lower half of pointer
                    ref = loadLowRefs[addr]
                    dis += "%s, %%lo(%s)(%s)" % (regs[get_rt(inst)], format_ref(self.make_load(ref[0]), ref[1]), regs[get_rs(inst)])
                else:
                    dis += "%s, %#X(%s)" % (regs[get_rt(inst)], get_signed_imm(inst), regs[get_rs(inst)])
            elif op_num == 36 or op_num == 37: # lbu, lhu
                if addr in loadLowRefs: # loading with immediate forming lower half of pointer
                    ref = loadLowRefs[addr]
                    dis += "%s, %%lo(%s)(%s)" % (regs[get_rt(inst)], format_ref(self.make_load(ref[0]), ref[1]), regs[get_rs(inst)])
                else:
                    dis += "%s, %#X(%s)" % (regs[get_rt(inst)], get_signed_imm(inst), regs[get_rs(inst)])
            elif (op_num == 49 or op_num == 50 or op_num == 53 or op_num == 54 or op_num == 57 or op_num == 58 or
                  op_num == 61 or op_num == 62): # load/store between co-processors
                if addr in loadLowRefs: # loading with immediate forming lower half of pointer
                    ref = loadLowRefs[addr]
                    dis += "%s, %%lo(%s)(%s)" % (float_reg(get_rt(inst)), format_ref(self.make_load(ref[0]), ref[1]), regs[get_rs(inst)])
                else:
                    dis += "%s, %#X(%s)" % (float_reg(get_rt(inst)), get_signed_imm(inst), regs[get_rs(inst)])
            elif op_num == 47: # cache
                if addr in loadLowRefs: # cache op with immediate forming lower half of pointer
                    ref = loadLowRefs[addr]
                    dis += "0x%02X, %%lo(%s)(%s)" % (get_rt(inst), format_ref(self.make_load(ref[0]), ref[1]), regs[get_rs(inst)])
                else:
                    dis += "0x%02X, %#X(%s)" % (get_rt(inst), get_signed_imm(inst), regs[get_rs(inst)])

        return dis

    def generate_undefined(self, path):
        self.first_pass() # find functions and variables
        with open(path + "/undef.txt", 'w', newline='\n') as f:
            for addr in sorted(self.vars):
                if addr < 0x80000000:
                    continue # Don't print out symbols of dmadata files' vrom addresses. These will be defined in another file.

                is_in_bss, region = self.is_in_bss(addr)
                if is_in_bss:
                    f.write("%s = %s_bss_start + 0x%08X;\n" % (self.make_load(addr), region[2], addr - region[0]))
                elif not self.is_in_data(addr):
                    f.write("%s = 0x%08X;\n" % (self.make_load(addr), addr))

# TODO -a --analyze flag? Only when its set will new symbols be added, otherwise use only the supplied ones
if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument('-u', '--undefined', help='create linker script for undefined symbols', metavar='path')
    parser.add_argument('-d', '--disassemble', help='disassemble supplied code files', metavar='path')
    parser.add_argument('-l', '--files', help='list of files to disassemble', metavar='filename', action='append')
    parser.add_argument('-f', '--functions', help='predefined functions', metavar='filename', action='append')
    parser.add_argument('-o', '--objects', help='predefined code objects', metavar='filename', action='append')
    parser.add_argument('-v', '--variables', help='predefined variables', metavar='filename', action='append')
    parser.add_argument('-a', '--auto-analysis', help='automatically find pointers and functions', action='store_true', default=False)
    args = parser.parse_args()

    for files_file in args.files:
        with open(files_file, 'r') as f:
            known_files = ast.literal_eval(f.read())
    for function_file in args.functions:
        with open(function_file, 'r') as f:
            known_funcs = ast.literal_eval(f.read())
    for object_file in args.objects:
        with open(object_file, 'r') as f:
            known_objects = ast.literal_eval(f.read())
    for var_file in args.variables:
        with open(var_file, 'r') as f:
            known_vars.update(ast.literal_eval(f.read()))

    dis = Disassembler()
    dis.load_defaults() # TODO file loading code should go in here

    if args.auto_analysis:
        dis.set_auto_analysis(True)

    if args.disassemble != None:
        os.makedirs(args.disassemble, exist_ok=True)
        dis.disassemble(args.disassemble)
    if args.undefined != None:
        os.makedirs(args.undefined, exist_ok=True)
        dis.generate_undefined(args.undefined)