Annotate some more of the code
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147
disasm.py
147
disasm.py
@ -22,15 +22,29 @@ import argparse
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parser = argparse.ArgumentParser()
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parser.add_argument('file', help='.bin file containing the initial memory dump')
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parser.add_argument('--hints', help='File(s) outlining additional jmp/call targets, label names, comments, etc', action='append')
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parser.add_argument('--smart', help='Given a raw Synacor challenge file, disassemble in a Synacor-aware manner', action='store_true')
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parser.add_argument('--aggressive-labels', help='Replace values with corresponding labels irrespective of where they appear', action='store_true')
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args = parser.parse_args()
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with open(args.file, 'rb') as data:
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SYN_MEM = memory_from_file(data)
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disassemble_end = len(SYN_MEM)
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labels, comments_before, comments_inline, replacements = {}, {}, {}, {}
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# Do smart things if requested
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if args.smart:
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disassemble_end = 0x17b4
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# Emulate 06bb to decrypt data
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for R1 in range(disassemble_end, 0x7562):
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R0 = SYN_MEM[R1]
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R0 ^= pow(R1, 2, 32768)
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R0 ^= 0x4154
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SYN_MEM[R1] = R0
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# Find things to label
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labels, comments_before, comments_inline, replacements = {}, {}, {}, {}
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SYN_PTR = 0
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while SYN_PTR < len(SYN_MEM):
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while SYN_PTR < disassemble_end:
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word = SYN_MEM[SYN_PTR]
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if word in instructions_by_opcode:
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instruction, SYN_PTR = Instruction.next_instruction(SYN_MEM, SYN_PTR)
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@ -93,18 +107,48 @@ MODE_DAT = False #False, 1 (data), 2 (text)
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SYN_PTR = 0
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def set_mode_out(mode):
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global MODE_OUT
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if MODE_OUT == mode:
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pass
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elif mode == False:
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# Switching off
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print('"')
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else:
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# Switching on
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print('{:04x}: out "'.format(SYN_PTR), end='')
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MODE_OUT = mode
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def set_mode_dat(mode):
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global MODE_DAT
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if MODE_DAT == mode:
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pass
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elif mode == False:
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# Switching off
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if MODE_DAT == 2:
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print('"', end='')
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print()
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elif MODE_DAT == 1:
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# Switching from data to text
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print()
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print('{:04x}: data "'.format(SYN_PTR), end='')
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elif MODE_DAT == 2:
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# Switching from text to data
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print('"')
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print('{:04x}: data'.format(SYN_PTR), end='')
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else:
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# Switching to a new mode
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print('{:04x}: data'.format(SYN_PTR), end='')
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if mode == 2:
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print('"', end='')
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MODE_DAT = mode
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def clear_modes():
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set_mode_out(False)
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set_mode_dat(False)
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while SYN_PTR < len(SYN_MEM):
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# Handle comments
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if SYN_PTR in comments_before:
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if MODE_OUT:
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print('"')
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MODE_OUT = False
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if MODE_DAT == 1:
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print()
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MODE_DAT = False
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if MODE_DAT == 2:
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print('"')
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MODE_DAT = False
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clear_modes()
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for comment in comments_before[SYN_PTR]:
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print('; {}'.format(comment))
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if SYN_PTR in comments_inline:
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@ -114,15 +158,7 @@ while SYN_PTR < len(SYN_MEM):
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# Handle labels
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if any(v == SYN_PTR for k, v in labels.items()):
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if MODE_OUT:
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print('"')
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MODE_OUT = False
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if MODE_DAT == 1:
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print()
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MODE_DAT = False
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if MODE_DAT == 2:
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print('"')
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MODE_DAT = False
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clear_modes()
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print('${}:'.format(next(k for k, v in labels.items() if v == SYN_PTR)))
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# Handle replacements
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@ -134,38 +170,17 @@ while SYN_PTR < len(SYN_MEM):
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word = SYN_MEM[SYN_PTR]
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if MODE_OUT and word != 19:
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print('"')
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MODE_OUT = False
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if MODE_DAT and 0 <= word <= 21:
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if MODE_DAT == 1:
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print()
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if MODE_DAT == 2:
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print('"')
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MODE_DAT = False
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if word not in instructions_by_opcode:
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if SYN_PTR >= disassemble_end or word not in instructions_by_opcode:
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# Data
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if 32 <= word <= 126:
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# looks like letters - unfortunately "\n" looks like MULT
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if MODE_DAT == 2:
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print(escape_char(chr(word)), end='')
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else:
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if MODE_DAT == 1:
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print()
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print('{:04x}: data "{}'.format(SYN_PTR, escape_char(chr(word))), end='')
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MODE_DAT = 2
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# Looks like letters - unfortunately "\n" looks like MULT
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set_mode_dat(2)
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print(escape_char(chr(word)), end='')
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if word == 0x0a:
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print('"')
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MODE_DAT = False # break on newlines
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clear_modes() # Break on newlines
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else:
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if MODE_DAT == 1:
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print(' {:04x}'.format(word), end='')
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else:
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if MODE_DAT == 2:
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print('"')
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print('{:04x}: data {:04x}'.format(SYN_PTR, word), end='')
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MODE_DAT = 1
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set_mode_dat(1)
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print(' {:04x}'.format(word), end='')
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SYN_PTR += 1
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else:
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# Instruction
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@ -173,30 +188,36 @@ while SYN_PTR < len(SYN_MEM):
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# Special cases
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if isinstance(instruction, InstructionOut):
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if isinstance(instruction.args[0], OpLiteral):
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if MODE_OUT:
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print(escape_char(chr(instruction.args[0].get(None))), end='')
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else:
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print('{:04x}: out "{}'.format(SYN_PTR, escape_char(chr(instruction.args[0].get(None)))), end='')
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MODE_OUT = True
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set_mode_out(True)
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print(escape_char(chr(instruction.args[0].get(None))), end='')
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if instruction.args[0].get(None) == 0x0a:
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print('"')
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MODE_OUT = False # break on newlines
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clear_modes() # Break on newlines
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else:
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if MODE_OUT:
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print('"')
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MODE_OUT = False
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clear_modes()
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print('{:04x}: {}{}'.format(SYN_PTR, instruction.describe(), comment_inline))
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elif isinstance(instruction, InstructionJmp) or isinstance(instruction, InstructionJt) or isinstance(instruction, InstructionJf) or isinstance(instruction, InstructionCall):
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clear_modes()
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if isinstance(instruction, InstructionJmp) or isinstance(instruction, InstructionCall):
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argidx = 0
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else:
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argidx = 1
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if isinstance(instruction.args[argidx], OpLiteral):
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loc = instruction.args[argidx].get(None)
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if any(v == loc for k, v in labels.items()):
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label = next(k for k, v in labels.items() if v == loc)
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instruction.args[argidx] = OpLabel(label)
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# Aggressively replace labels if requested
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for argnum in range(instruction.nargs) if args.aggressive_labels else [argidx]:
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if isinstance(instruction.args[argnum], OpLiteral):
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loc = instruction.args[argnum].get(None)
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if any(v == loc for k, v in labels.items()):
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label = next(k for k, v in labels.items() if v == loc)
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instruction.args[argnum] = OpLabel(label)
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print('{:04x}: {}{}'.format(SYN_PTR, instruction.describe(), comment_inline))
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else:
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# Aggressively replace labels if requested
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if args.aggressive_labels:
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for argnum in range(instruction.nargs):
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if isinstance(instruction.args[argnum], OpLiteral):
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loc = instruction.args[argnum].get(None)
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if any(v == loc for k, v in labels.items()):
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label = next(k for k, v in labels.items() if v == loc)
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instruction.args[argnum] = OpLabel(label)
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clear_modes()
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print('{:04x}: {}{}'.format(SYN_PTR, instruction.describe(), comment_inline))
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SYN_PTR = next_SYN_PTR
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@ -56,16 +56,11 @@ ren sub_0505 self_test_call_subroutine1
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lbl 02c2 self_test_call_returnloc1
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ren label_0509 self_test_call_fail
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ren label_02c4 self_test_call_check_stack1
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rep 02c6 eq R1 R0 $self_test_call_check_stack1
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cmi 02c6 This test is strange. If R0 == 02c2 as tested below, R0 != 02c4 is guaranteed
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rep 02cd eq R1 R0 $self_test_call_returnloc1
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cmb 02d4 Test call register value
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ren sub_0507 self_test_call_subroutine2
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lbl 02d9 self_test_call_returnloc2
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rep 02d4 set R0 $self_test_call_subroutine2
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ren label_02db self_test_call_check_stack2
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rep 02dd eq R1 R0 $self_test_call_check_stack2
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rep 02e4 eq R1 R0 $self_test_call_returnloc2
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cmb 02eb Test add overflow
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ren label_0520 self_test_overflow_fail
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cmi 0304 Just to be safe!
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@ -80,15 +75,48 @@ lbl 034b self_test_rwmem_data
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cmb 034b Test rmem/wmem
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ren label_04d7 self_test_rmem_fail
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ren label_04ee self_test_wmem_fail
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rep 034d rmem R0 $self_test_rwmem_data
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rep 0357 add R2 $self_test_rwmem_data 0001
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rep 0365 set R0 $self_test_rwmem_data
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ren sub_06bb decrypt_data
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cmi 0375 Sneaky!
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cmb 0375 Sneaky!
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cmb 0375 call $decrypt_data
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rep 0375 nop
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rep 0376 nop
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lbl 17b4 encrypted_data
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rep 0377 rmem R0 $encrypted_data
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rep 0381 add R2 $encrypted_data 0001
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ren label_03ad self_test_wmem_cmd_fail
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rep 03ab out $self_test_complete
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cmi 03a9 Becomes noop; jt 0013 $self_test_complete
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lbl 03d2 self_test_complete
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lbl 17c0 str_self_test_result
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cmi 03d6 The "F"
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lbl 17e4 str_complete
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ren label_03e8 self_test_loop_copy_complete
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cmb 03e8 Copy the "complete" string over the "FAILED!!" substring of $str_self_test_result
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ren label_03ff self_test_concat_all_pass
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cmb 03ff Extend $str_self_test_result to include $str_self_test_all_pass
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lbl 17d3 str_self_test_all_pass
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cmi 0410 ASCII comma
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cmi 0428 Print self-test completion string
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cmi 0430 Jump to game loop
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ren label_0aae after_self_test
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ren sub_05b2 loop_string
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cmb 05b2 % Loops over a string and calls a callback for each character
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cmb 05b2 % @param R0 Pointer to the string to loop over
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cmb 05b2 % @param R1 Pointer to the callback to call with the character in R0
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ren label_05c8 loop_string_loop_chars
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ren label_05e3 loop_string_loop_chars_done
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ren sub_05ee print_string
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cmb 05ee % Prints a string to output
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cmb 05ee % @param R0 Pointer to the string to print
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ren sub_05f8 print_char
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cmb 05f8 % Prints a single character to output
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cmb 05f8 % Most useful as a callback to $loop_string
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cmb 05f8 % @param R0 The character to print
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ren sub_05fb print_char_xored
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cmb 05fb % Prints a single character to output after XORing with a fixed value
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cmb 05fb % Most useful as a callback to $loop_string
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cmb 05fb % @param R0 The input character
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cmb 05fb % @param R2 The other XOR operand
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ren sub_084d xor
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cmb 084d % Calculates the exclusive OR (XOR) of two values
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cmb 084d % @param R0 The first XOR operand
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cmb 084d % @param R1 The second XOR operand
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cmb 084d % @return R0 The value R0 XOR R1
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