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Circuit tracks firmware reverse engineering
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| import numpy as np | |
| from pathlib import Path | |
| import crcmod | |
| import sys | |
| def extract_sysex_messages(syx_path): | |
| commands_list = dict([ | |
| (0x71, "UPDATE_INIT"), | |
| (0x72, "UPDATE_WRITE"), | |
| (0x73, "UPDATE_FINISH"), | |
| (0x76, "UPDATE_FOOTER"), | |
| (0x7c, "UPDATE_HEADER"), | |
| ]) | |
| def parse_nibble(data): | |
| result = 0 | |
| for byte_value in data: | |
| result = result << 4 | |
| result |= byte_value | |
| return result | |
| with open(syx_path, 'rb') as syx_file: | |
| data = syx_file.read() | |
| finalFirmwareFile = np.empty([0],dtype=np.uint8) | |
| i = 0 | |
| while i < len(data): | |
| if data[i] == 0xF0: #SysEx start byte | |
| end_index = data.find(0xF7, i) #SysEx end byte | |
| if end_index == -1: | |
| raise ValueError("Missing SysEx end byte") | |
| novation_header = bytes([0x00, 0x20, 0x29, 0x00]) | |
| if data[i+1:i+5] != novation_header: | |
| raise ValueError("File is missing novation header") | |
| command = commands_list[data[i+5]] | |
| cropped_data = data[i+6:end_index] | |
| if command == "UPDATE_INIT": | |
| version = parse_nibble(cropped_data[2:8]) | |
| if cropped_data[1] == 0x64: | |
| print("target: circuit tracks") | |
| elif cropped_data[1] == 0x63: | |
| print("target: circuit rhythm") | |
| else: | |
| print(hex(cropped_data)) | |
| print(0x1d) | |
| print(f"init version: {version}") | |
| elif command == "UPDATE_HEADER": | |
| version = parse_nibble(cropped_data[1:7]) | |
| print(f"header version: {version}") | |
| filesize = parse_nibble(cropped_data[7:15]) | |
| print(f"header filesize: {hex(filesize)}") | |
| checksum = parse_nibble(cropped_data[15:23]) | |
| print(f"header checksum: {hex(checksum)}") | |
| elif command in ["UPDATE_WRITE", "UPDATE_FINISH"]: | |
| #need to tightly pack 7bit MIDI bytes into 8bit firmware file | |
| packed = np.frombuffer(cropped_data, dtype=np.uint8) | |
| unpacked = np.unpackbits(packed[:, np.newaxis], axis=1) | |
| unpacked = unpacked[:, 1:].reshape(-1) #discard first bit of each byte and make continuous array | |
| repacked = np.packbits(unpacked[:-3]) #last three bits are just padding | |
| if command == "UPDATE_FINISH": | |
| finalFirmwareFile = np.concatenate([repacked, finalFirmwareFile]) | |
| break | |
| else: | |
| finalFirmwareFile = np.concatenate([finalFirmwareFile, repacked]) | |
| i = end_index + 1 | |
| else: | |
| i += 1 | |
| finalFirmwareFile = bytes(finalFirmwareFile[:filesize]) | |
| crc32_non_reflected = crcmod.mkCrcFun(0x104C11DB7, rev=False, initCrc=0xFFFFFFFF, xorOut=0x00000000) | |
| calculated_checksum = crc32_non_reflected(finalFirmwareFile) | |
| if calculated_checksum != checksum: | |
| raise ValueError(f"File checksum {calculated_checksum} does not match header checksum {checksum}") | |
| with open(syx_path.with_suffix(".bin"), 'wb') as f: | |
| f.write(finalFirmwareFile) | |
| if len(sys.argv)!=2: | |
| print("need to give a path to a .syx file") | |
| extract_sysex_messages(Path(sys.argv[1])) |
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Sure add me
I will try to look into pitch shifting again, honestly I have very little experience with all the DSP stuff so most of the heavy lifting was done by using this method https://wilgibbs.com/blog/defcon-finals-mcp/