#!/usr/bin/python3

# The OS/K Team licenses this file to you under the MIT license.
# See the LICENSE file in the project root for more information.

import re
import os
import sys
import subprocess
from array import array
from tempfile import TemporaryFile
from collections import OrderedDict

WANT_DISASM = False

if len(sys.argv) != 5:
    print("Usage: {} (output file) (memory entry point) (source file) (symbols file)"
                    .format(sys.argv[0]))
    sys.exit(1)

source = TemporaryFile(mode="w+")
instrs = TemporaryFile(mode="w+")
b_data = TemporaryFile(mode="w+b")
b_text = TemporaryFile(mode="w+b")

lst_regs = open(os.path.join(sys.path[0], "regs.lst"))
lst_instrs = open(os.path.join(sys.path[0], "instrs.lst"))

main_src = open(sys.argv[1])
b_out = open(sys.argv[3], "wb")
b_sym = open(sys.argv[4], "w")

start_addr = int(sys.argv[2], base=0)

os.chdir(os.path.dirname(sys.argv[1]))

def leave():
    source.close()
    instrs.close()
    b_out.close()
    b_sym.close()
    b_data.close()
    b_text.close()
    main_src.close()
    lst_regs.close()
    lst_instrs.close()

#-------------------------------------------------------------------------------

# Defines
pdefs = dict()

# registers
pregs = list()

# instructions
pinstrs = list()

# labels
plabels_text = OrderedDict()
plabels_data = OrderedDict()

# size of .data section
pdata = 0

# size of .text section
ptext = 0

# for local labels
plastlabel = ''

# after parse() is done, pdata and ptext are never modified

#-------------------------------------------------------------------------------

def name_valid(name):
    for c in name.lower():
        if not(c in 'abcdefghijklmnopqrstuvwxyz0123456789[$._+]=,'):
            return False
    return True

def is_number(s):
    try:
        int(s, base=0)

    except ValueError:
        return False

    return True

arith_expr = re.compile(r'((0x[0-9A-Fa-f]+|[0-9]+)\s*([|&^+\-*]|<<|>>))+\s*(0x[0-9A-Fa-f]+|[0-9]+)')

def arith_eval(s):
    if arith_expr.match(s):
        return str(eval(s))
    return s

#-------------------------------------------------------------------------------

def parse_lst_regs():
    global pregs
    for _, line in enumerate(lst_regs):
        pregs.append(line.strip())

def parse_lst_instrs():
    global pinstrs
    for _, line in enumerate(lst_instrs):
        pinstrs.append(line.strip())

#-------------------------------------------------------------------------------

inc_depth = 0
inc_depth_max = 16

# Quickly goes through source file and resolves "include" directives ONLY
def do_includes(fi):
    global inc_depth
    for _, line in enumerate(fi):
        line = line.rstrip()
        tok = line.split(None, 1)

        if len(tok) == 0:
            continue

        if tok[0] == "include":
            if len(tok) == 1:
                print("Missing parameter for include directive")
                leave()
                sys.exit(1)

            if tok[1][0] not in "'\"" or tok[1][-1] != tok[1][0]:
                print("Invalid format for include directive: {}".format(line))
                leave()
                sys.exit(1)

            inc = tok[1][1:-1]

            try:
                new_fi = open(inc, "r")

            except:
                print("Couldn't open file: {}".format(line))
                leave()
                sys.exit(1)

            inc_depth += 1
            if inc_depth >= inc_depth_max:
                print("Maximal include depth reached: {}".format(line))
                leave()
                sys.exit(1)

            do_includes(new_fi)

        else:
            source.write("{}\n".format(line))

    inc_depth -= 1


#-------------------------------------------------------------------------------

def parse():
    global ptext
    global plastlabel

    source.seek(0)

    for count, line in enumerate(source):
        line = line.rstrip()

        if len(line) == 0:
            continue

        quote = False
        for i in range(len(line)):
            if line[i] in "'\"":
                quote = not quote

            if line[i] in '#;@!/' and not quote:
                line = line[:i].rstrip()
                break

        if quote:
            print("Unterminated string in line: {}".format(line))
            leave()
            sys.exit(1)

        if len(line) == 0:
            continue

        if line[0] == ' ' or line[0] == '\t':
            line = line.lstrip()
            instrs.write(hex(ptext + start_addr) + ' ')
            ptext += parse_instr(line)
            instrs.write("\n")

            continue

        # Preprocessor or label?
        if line[-1] == ':':
            if name_valid(line[:-1]):
                label = line[:-1]
                if label[0] == '.':
                    label = plastlabel + label
                else:
                    plastlabel = label
                plabels_text[label] = ptext
            else:
                print("Bad label name: {}".format(line[:-1]))
                leave()
                sys.exit(1)
            continue

        # Preprocessor, .data, or invalid
        parse_preproc(line)

#-------------------------------------------------------------------------------

def parse_preproc(line):
    global pdata

    tok = line.split(None, 2)

    # preprocessor
    if len(tok) > 1 and tok[1] == ':=':
        if len(tok) < 3:
            print("Invalid format: {}".format(line))
            leave()
            sys.exit(1)
        pdefs[tok[0]] = tok[2]
        return

    # .data
    if len(tok) > 1 and tok[1] == '=':
        if len(tok) < 3:
            print("Invalid format: {}".format(line))
            leave()
            sys.exit(1)

        label = tok[0]
        if label[0] == '.':
            label = plastlabel + label

        plabels_data[label] = pdata

        # number data
        if is_number(tok[2]):
            written = b_data.write(int(tok[2], base=0).to_bytes(8, byteorder='little', signed=False))
            assert(written == 8)
            pdata += written

        # buffer / bss
        elif tok[2][0] == '[':
            assert(tok[2][-1] == ']')
            
            s = tok[2][1:-1].strip()
            if not is_number(s):
                print("Invalid bss format: {}".format(line))
                leave()
                sys.exit(1)

            i = int(s, base=0)
            i = i + (8 - i % 8)
            written = b_data.write(bytearray(i))
            assert(written == i)

            pdefs[label + "_len"] = s
            pdata += written

        # string data
        elif tok[2][0] in "'\"":
            s = tok[2].strip()
            assert(s[-1] == tok[2][0])

            s = s[1:-1]

            real_len = 0
            escaping = False

            for c in s:
                # escape sequences
                if c == '\\':
                    escaping = True
                    continue

                if escaping:
                    escaping = False

                    if c == 'n':
                        c = '\n'
                    elif c == 't':
                        c = '\t'
                    else:
                        print("Unrecognized escape sequence: {}".format(line))
                        leave()
                        sys.exit(1)

                written = b_data.write(ord(c).to_bytes(1, byteorder='little', signed=False))
                assert(written == 1)
                real_len += 1
                pdata += 1

            # align
            for i in range(8 - len(s) % 8):
                written = b_data.write(int(0).to_bytes(1, byteorder='little', signed=False))
                assert(written == 1)
                pdata += 1

            pdefs[label + "_len"] = str(real_len)

        else:
            print("Invalid format: {}".format(line))
            leave()
            sys.exit(1)

        return

    print("Unrecognized directive: {}".format(line))
    leave()
    sys.exit(1)

#-------------------------------------------------------------------------------

pconds = {
    'c':    0b00001,
    'o':    0b00010,
    'z':    0b00011,
    'e':    0b00011,
    's':    0b00100,
    'p':    0b00101,
    'a':    0b00110,
    'ae':   0b00111,
    'b':    0b01000,
    'be':   0b01001,
    'g':    0b01010,
    'ge':   0b01011,
    'l':    0b01100,
    'le':   0b01101,
    'cxz':  0b01110,
    'cxnz': 0b11110,
}

def get_cond_mask(cond, line):
    mask = 0

    if cond[0] == 'n':
        cond = cond[1:]
        mask = 0b10000
    
    if cond not in pconds:
        print("Invalid condition suffix: {}".format(line))
        leave()
        sys.exit(1)

    return (mask | pconds[cond]) << 10

#-------------------------------------------------------------------------------

pfts = {
    "reg":      0b00001,
    "imm64":    0b00010,

    "bimm64":   0b00100,
    "brr":      0b00101,
    "brri":     0b00110,
    "brrii":    0b00111,

    "wimm64":   0b01000,
    "wrr":      0b01001,
    "wrri":     0b01010,
    "wrrii":    0b01011,

    "limm64":   0b01100,
    "lrr":      0b01101,
    "lrri":     0b01110,
    "lrrii":    0b01111,

    "qimm64":   0b10000,
    "qrr":      0b10001,
    "qrri":     0b10010,
    "qrrii":    0b10011,
}

def get_fts_mask(ft, line):
    if ft not in pfts:
        print("Invalid operand format ({}): {}".format(ft, line))

    else:
        return pfts[ft]
    
#-------------------------------------------------------------------------------

def parse_instr(line):
    if line == None or len(line) == 0:
        return 0

    tok = line.split(None, 1)

    instr = tok[0].strip()

    if len(tok) > 1:
        params = tok[1].strip()
    else:
        params = None

    fellthrough = False

    size = 4
    
    # Word 2 (rep|cond|ft1|ft2)
    w2 = 0

    if len(instr) > 2 and '.' in instr:
        instr, suf = instr.split('.', 1)
        
        if len(instr) == 0:
            print("Missing instruction name before suffixes: {}".format(line))

        if len(suf) > 2 and suf[:3] == "rep":
            if len(suf) > 3:
                suf = suf[3:]

                if len(suf) > 0 and suf[0] == '.':
                    suf = suf[1:]
            else:
                suf = ''

            w2 |= 0x8000 # REP
        
        if len(suf) > 0:
            w2 |= get_cond_mask(suf, line)

    instr_name = instr
    instr_args = ''

    if params == None or len(params) == 0:
        instrs.write("{} ".format(instr_name))
        instrs.write("%%imm16 {}".format(w2))

        return size

    tok = params.split(',')
    
    # FT1 and FT2
    fts = ''

    #
    # Parse operands, generating fts along the way
    #
    for word in tok:
        word = word.strip()

        instr_args += ' '

        gotPref = False
        if len(fts) != 0:
            fts += ' '

        # preprocessor
        if word in pdefs:
            word = pdefs[word]
            # Fall through

        if len(word) == 0:
            continue

        # arithmetic expressions
        word = arith_eval(word)

        # memory length prefixes
        if len(word) > 2 and '[' in word:
            if word[0] in 'bwlq':
                fts += word[0]
                gotPref = True
            else:
                print("Bad memory length prefix: {}".format(line))
                leave()
                sys.exit(1)

            word = word[1:].strip()
            assert(word[0] == '[')

        #
        # Determine memory format and save it into fts
        #
        if word[0] == '[':
            assert(word[-1] == ']')
            word = word[1:-1]
            
            # preprocessor, again
            if word in pdefs:
                word = pdefs[word]
                # Fall through

            #
            # Make sure we got an access length prefix
            #
            if not gotPref:
                print("Missing access length modifier: {}".format(line))
                leave()
                sys.exit(1)

            instr_name += "_m"

            # cheap way of getting [reg - imm] to work
            word = word.replace('-', '+ -')
            
            # remove every spaces!
            word = word.replace(' ', '')

            #
            # Offsets
            #
            if '+' in word:
                reg1 = "inv"
                reg2 = "inv"
                imm1 = '1'
                imm2 = '0'

                wtok = word.split('+')

                #
                # [reg] and [reg*imm16]
                #

                if len(wtok) == 1:
                    if '*' in wtok[0]:
                        assert(len(wtok[0].split('*')) == 2)

                        reg2, imm1 = wtok[0].split('*', 1)
                    
                    else:
                        reg1 = wtok[0]

                #
                # [reg+reg], [reg+imm16], [reg*imm16+imm16], [reg+reg*imm16]
                #
                elif len(wtok) == 2:
                    # Must be [reg*imm16+imm16]
                    if '*' in wtok[0]:
                        assert(len(wtok[0].split('*')) == 2)
                        assert(is_number(wtok[1].strip()))

                        print(wtok)
                        reg2, imm1 = wtok[0].split('*', 1)
                        imm2 = wtok[1]

                    # Must be [reg+reg*imm16]
                    elif '*' in wtok[1]:
                        assert(len(wtok[1].split('*')) == 2)

                        reg1 = wtok[0]
                        reg2, imm1 = wtok[1].split('*', 1)

                    elif is_number(wtok[1].strip()):
                        reg1 = wtok[0]
                        imm2 = wtok[1]

                    # Must be [reg+reg]
                    else:
                        reg1 = wtok[0]
                        reg2 = wtok[1]

                #
                # [reg+reg+imm16], [reg+reg*imm16+imm16]
                #
                else:
                    assert(len(wtok) == 3)
                    
                    reg1 = wtok[0]
                    imm2 = wtok[2]
                    
                    if '*' in wtok[1]:
                         assert(len(wtok[1].split('*')) == 2)
                         reg2, imm1 = wtok[1].split('*', 1)

                    else:
                        reg2 = wtok[1]

                #
                # Update fts and instr_args
                #

                instr_args += "{}:{} ".format(reg2, reg1)
                size += 2

                if imm1 == '1':
                    if imm2 == '0':
                        fts += 'rr'
                    else:
                        fts += 'rri'
                        size += 2
                        instr_args += "%%imm16 {}".format(imm2)

                else:
                    size += 4
                    fts += 'rrii'
                    instr_args += "%%imm16 {} %%imm16 {}".format(imm1, imm2)

                continue

            #
            # [imm64] or [reg]
            #
            else:
                fellthrough = True
                # FALLTHROUGH

        # preprocessor, yet again
        if word in pdefs:
            word = pdefs[word]
            # Fall through

        # characters 'c'
        if len(word) == 3 and word[0] == word[-1] == "'":
            word = str(ord(word[1]))

        # register index $reg
        if len(word) == 4 and word[0] == '$':
            if word[1:] in pregs:
                word = str(pregs.index(word[1:]))

        # for now every immediate is 64-bit
        if is_number(word):
            # +8 for immediate
            size += 8

            if not fellthrough:
                instr_name += "_i"
            
            fts += "imm64"

            instr_args += "%%imm64 "
            instr_args += word

            fellthrough = False
            continue

        # register
        if word in pregs:
            size += 2

            if not fellthrough:
                instr_name += "_r"
                fts += "reg"

            else:
                fts += "rr"

            instr_args += word
            fellthrough = False
            continue

        # it's a label (a 64-bit immediate)
        # +8 for immediate
        size += 8

        if not fellthrough:
            instr_name += "_i"

        fts += "imm64"
        instr_args += "%%imm64 "

        if word[0] == '.':
            instr_args += plastlabel

        instr_args += word
        fellthrough = False

    #
    # Compute FT1 and FT2
    #
    if ' ' in fts:
        assert(len(fts.split()) == 2)
        ft1, ft2 = fts.split()
        
        w2 |= get_fts_mask(ft1, line) << 5
        w2 |= get_fts_mask(ft2, line)

    else:
        assert(len(fts) > 0)
        w2 |= get_fts_mask(fts, line) << 5

    instrs.write("{} %%imm16 {}{}".format(instr_name, w2, instr_args))
    return size

#-------------------------------------------------------------------------------

special_syms = {
    "%%imm16",
    "%%imm32",
    "%%imm64",
    "%%signed"
}

def gentext():
    text_start = start_addr
    data_start = text_start + ptext
    data_start += (8 - data_start % 8)

    instrs.seek(0)

    for _, line in enumerate(instrs):
        tok = line.strip().split()

        if WANT_DISASM:
            print(tok)

        tok = tok[1:]

        for word in tok:
            if len(word) == 0:
                continue
        
            if word in pregs:
                idx = pregs.index(word)
                b_text.write(idx.to_bytes(2, byteorder='little', signed=False))
                continue

            if ':' in word:
                if len(word.split(':')) < 2:
                    print("Stray ':' in line: {}".format(line))
                    leave()
                    sys.exit(1)

                reg2, reg1 = word.split(':', 1)
                idx1 = pregs.index(reg1)
                idx2 = pregs.index(reg2)
                b_text.write(((idx1 << 8) | idx2).to_bytes(2, byteorder='little', signed=False))
                continue

            if word in pinstrs:
                idx = pinstrs.index(word)
                b_text.write(idx.to_bytes(2, byteorder='little', signed=False))
                continue

            if word in plabels_text:
                addr = text_start + plabels_text[word]
                b_text.write(addr.to_bytes(8, byteorder='little', signed=False))
                continue

            if word in plabels_data:
                addr = data_start + plabels_data[word]
                b_text.write(addr.to_bytes(8, byteorder='little', signed=False))
                continue

            if word in special_syms:
                if word == "%%imm16":
                    lastimm = 2
                elif word == "%%imm32":
                    lastimm = 4
                elif word == "%%imm64":
                    lastimm = 8

                elif word == "%%signed":
                    lastimm = 2
                    isSigned = True
                else:
                    isSigned = False

                continue

            if is_number(word):
                if word[0] == '-':
                    isSigned = True
                else:
                    isSigned = False
                b_text.write(int(word, base=0).to_bytes(lastimm, byteorder='little', signed=isSigned))
                continue

            print("Assembly error, unknown token '{}' in line: {}".format(word, line))
            leave()
            sys.exit(1)

#-------------------------------------------------------------------------------

def sort_by_list(dict_, list_):
    for key in list_:
        dict_.move_to_end(key)

def gensym():
    text_start = start_addr
    data_start = text_start + ptext
    data_start += (8 - data_start % 8)

    for label in plabels_text:
        plabels_text[label] += text_start

    for label in plabels_data:
        plabels_data[label] += data_start

    plabels_all = OrderedDict(list(plabels_text.items()) + list(plabels_data.items()))

    for key, value in sorted(plabels_all.items(), key=lambda item: item[1]):
        b_sym.write("{} {}\n".format(key, value))

#-------------------------------------------------------------------------------

def genout():
    b_text.seek(0)
    b_data.seek(0)
    b_out.write(b_text.read())

    data_align = (8 - ptext % 8)

    for i in range(data_align):
        b_out.write(int(0).to_bytes(1, byteorder='little', signed=False))

    b_out.write(b_data.read())

#-------------------------------------------------------------------------------

parse_lst_instrs()
parse_lst_regs()
do_includes(main_src)
parse()
gentext()
genout()
gensym()
leave()
sys.exit(0)