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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,173 @@ | ||
| #!/usr/bin/env python3 | ||
|
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| import math | ||
| import struct | ||
| import sys | ||
|
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| # bootrom descrambler reversed by segher | ||
| def scramble(data, *, qoobsx=False): | ||
| acc = 0 | ||
| nacc = 0 | ||
|
|
||
| t = 0x2953 | ||
| u = 0xD9C2 | ||
| v = 0x3FF1 | ||
|
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| x = 1 | ||
|
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| if qoobsx: | ||
| # Qoob SX scrambling starts at 0x210000 | ||
| # Use a custom initialization vector to speed things up | ||
| acc = 0xCB | ||
| nacc = 0 | ||
|
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| t = 0x9E57 | ||
| u = 0xC7C5 | ||
| v = 0x2EED | ||
|
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| x = 1 | ||
|
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| it = 0 | ||
| while it < len(data): | ||
| t0 = t & 1 | ||
| t1 = (t >> 1) & 1 | ||
| u0 = u & 1 | ||
| u1 = (u >> 1) & 1 | ||
| v0 = v & 1 | ||
|
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| x ^= t1 ^ v0 | ||
| x ^= u0 | u1 | ||
| x ^= (t0 ^ u1 ^ v0) & (t0 ^ u0) | ||
|
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| if t0 == u0: | ||
| v >>= 1 | ||
| if v0: | ||
| v ^= 0xB3D0 | ||
|
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| if t0 == 0: | ||
| u >>= 1 | ||
| if u0: | ||
| u ^= 0xFB10 | ||
|
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| t >>= 1 | ||
| if t0: | ||
| t ^= 0xA740 | ||
|
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| nacc = (nacc + 1) % 256 | ||
| acc = (acc * 2 + x) % 256 | ||
| if nacc == 8: | ||
| data[it] ^= acc | ||
| nacc = 0 | ||
| it += 1 | ||
|
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||
| return data | ||
|
|
||
| def flatten_dol(data): | ||
| header = struct.unpack(">64I", data[:256]) | ||
| offsets = header[:18] | ||
| addresses = header[18:36] | ||
| sizes = header[36:54] | ||
| bss_address = header[54] | ||
| bss_size = header[55] | ||
| entry = header[56] | ||
|
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| dol_min = min(a for a in addresses if a) | ||
| dol_max = max(a + s for a, s in zip(addresses, sizes)) | ||
|
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| img = bytearray(dol_max - dol_min) | ||
|
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| for offset, address, size in zip(offsets, addresses, sizes): | ||
| img[address - dol_min:address + size - dol_min] = data[offset:offset + size] | ||
|
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| # Entry point, load address, memory image | ||
| return entry, dol_min, img | ||
|
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| def pack_uf2(data, base_address): | ||
| ret = bytearray() | ||
|
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| seq = 0 | ||
| addr = base_address | ||
| chunk_size = 256 | ||
| total_chunks = math.ceil(len(data) / chunk_size) | ||
| while data: | ||
| chunk = data[:chunk_size] | ||
| data = data[chunk_size:] | ||
|
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||
| ret += struct.pack( | ||
| "< 8I 476B I", | ||
| 0x0A324655, # Magic 1 "UF2\n" | ||
| 0x9E5D5157, # Magic 2 | ||
| 0x00002000, # Flags (family ID present) | ||
| addr, | ||
| chunk_size, | ||
| seq, | ||
| total_chunks, | ||
| 0xE48BFF56, # Board family: Raspberry Pi RP2040 | ||
| *chunk.ljust(476, b"\x00"), | ||
| 0x0AB16F30, # Final magic | ||
| ) | ||
|
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| seq += 1 | ||
| addr += chunk_size | ||
|
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| return ret | ||
|
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| def main(): | ||
| if len(sys.argv) != 3: | ||
| print(f"Usage: {sys.argv[0]} <output> <executable>") | ||
| return 1 | ||
|
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||
| output = sys.argv[1] | ||
| executable = sys.argv[2] | ||
|
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| with open(executable, "rb") as f: | ||
| exe = bytearray(f.read()) | ||
|
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| if executable.endswith(".dol"): | ||
| entry, load, img = flatten_dol(exe) | ||
| entry &= 0x017FFFFF | ||
| entry |= 0x80000000 | ||
| load &= 0x017FFFFF | ||
| size = len(img) | ||
|
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||
| print(f"Entry point: 0x{entry:0{8}X}") | ||
| print(f"Load address: 0x{load:0{8}X}") | ||
| print(f"Image size: {size} bytes ({size // 1024}K)") | ||
| elif executable.endswith(".elf"): | ||
| pass | ||
| else: | ||
| print("Unknown input format") | ||
| return -1 | ||
|
|
||
| if output.endswith(".uf2"): | ||
| if entry != 0x81300000 or load != 0x01300000: | ||
| print("Invalid entry point and base address (must be 0x81300000)") | ||
| return -1 | ||
|
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| img = scramble(bytearray(0x720) + img)[0x720:] | ||
|
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| align_size = 4 | ||
| img = ( | ||
| img.ljust(math.ceil(len(img) / align_size) * align_size, b"\x00") | ||
| + b"PICO" | ||
| ) | ||
|
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| header_size = 32 | ||
| header = struct.pack( | ||
| "> 8B I 20x", | ||
| *b"IPLBOOT ", | ||
| len(img) + header_size, | ||
| ) | ||
| assert len(header) == header_size | ||
|
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| out = pack_uf2(header + img, 0x10080000) | ||
|
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| else: | ||
| print("Unknown output format") | ||
| return -1 | ||
|
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| with open(output, "wb") as f: | ||
| f.write(out) | ||
|
|
||
| if __name__ == "__main__": | ||
| sys.exit(main()) |
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