copapy/tools/extract_code.py

from copapy._binwrite import data_reader, Command, ByteOrder
import argparse
from typing import Literal


def patch(data: bytearray, offset: int, patch_mask: int, value: int, byteorder: Literal['little', 'big']) -> None:
    # Read 4 bytes at the offset as a little-endian uint32
    original = int.from_bytes(data[offset:offset+4], byteorder)

    shift_factor = patch_mask & -patch_mask

    # Apply the patch
    new_value = (original & ~patch_mask) | ((value * shift_factor) & patch_mask)

    # Write the new value back to the bytearray
    data[offset:offset+4] = new_value.to_bytes(4, byteorder)


def patch_hi21(data: bytearray, offset: int, page_offset: int, byteorder: Literal['little', 'big']) -> None:
    # ADRP immediate is signed 21 bits: valid range [-2^20, 2^20 - 1]
    if not (-(1 << 20) <= page_offset < (1 << 20)):
        raise ValueError(f"page_offset {page_offset} out of 21-bit range")

    # Load current 32-bit instruction from data
    instr_bytes = data[offset:offset+4]
    instr = int.from_bytes(instr_bytes, byteorder)

    # Split the page offset into immhi and immlo
    immlo = page_offset & 0x3          # bits[1:0]
    immhi = (page_offset >> 2) & 0x7FFFF  # bits[20:2] (19 bits)

    # Clear previous immhi and immlo bits (bits 23:5 and 30:29)
    instr &= ~((0x7FFFF << 5) | (0x3 << 29))

    # Insert new immhi and immlo fields
    instr |= (immhi << 5) | (immlo << 29)

    #instr ^= (1 << 23)

    print(f"->>> page_offset=0x{page_offset:x}, immhi=0x{immhi:x}, immlo=0x{immlo:x}, instr=0x{instr:x}")
    print(f"     page_offset=0x{page_offset:x}, immhi=0x{immhi:b}, immlo=0x{immlo:b}, instr=0x{instr:b}")

    # Store the patched instruction back into the bytearray
    data[offset:offset+4] = instr.to_bytes(4, byteorder)


if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument("input_file", type=str, help="Input file path with copapy commands")
    parser.add_argument("output_file", type=str, help="Output file with patched code")
    parser.add_argument("--data_section_offset", type=int, default=-0x1000, help="Offset for data relative to code section")
    parser.add_argument("--byteorder", type=str, choices=['little', 'big'], default='little', help="Select byteorder")
    args = parser.parse_args()

    input_file: str = args.input_file
    output_file: str = args.output_file
    data_section_offset: int = args.data_section_offset
    byteorder: ByteOrder = args.byteorder

    with open(input_file, mode='rb') as f_in:
        dr = data_reader(f_in.read(), byteorder)

    buffer_index: int = 0
    end_flag: int = 0
    program_data: bytearray = bytearray([])

    while (end_flag == 0):
        com = dr.read_com()

        if com == Command.ALLOCATE_DATA:
            size = dr.read_int()
            print(f"ALLOCATE_DATA size={size}")
        elif com == Command.ALLOCATE_CODE:
            size = dr.read_int()
            program_data = bytearray(size)
            print(f"ALLOCATE_CODE size={size}")
        elif com == Command.COPY_DATA:
            offs = dr.read_int()
            size = dr.read_int()
            datab = dr.read_bytes(size)
            print(f"COPY_DATA offs=0x{offs + data_section_offset:x} size={size} data={' '.join(hex(d) for d in datab)}")
        elif com == Command.COPY_CODE:
            offs = dr.read_int()
            size = dr.read_int()
            datab = dr.read_bytes(size)
            program_data[offs:offs + size] = datab
            print(f"COPY_CODE offs=0x{offs:x} size={size} data={' '.join(hex(d) for d in datab[:5])}...")
        elif com == Command.PATCH_FUNC:
            offs = dr.read_int()
            mask = dr.read_int()
            scale = dr.read_int()
            value = dr.read_int(signed=True)
            patch(program_data, offs, mask, value // scale, byteorder)
            print(f"PATCH_FUNC patch_offs=0x{offs:x} mask=0x{mask:x} scale=0x{scale:x} value=0x{value:x}")
        elif com == Command.PATCH_OBJECT:
            offs = dr.read_int()
            mask = dr.read_int()
            scale = dr.read_int()
            value = dr.read_int(signed=True)
            patch(program_data, offs, mask, value // scale + data_section_offset // scale, byteorder)
            print(f"PATCH_OBJECT patch_offs=0x{offs:x} mask=0x{mask:x} scale=0x{scale:x} value=0x{value + data_section_offset:x}")
            print(f" | calculated value: 0x{(value // scale + data_section_offset // scale):x}")
        elif com == Command.PATCH_OBJECT_HI21:
            offs = dr.read_int()
            mask = dr.read_int()
            scale = dr.read_int()
            value = dr.read_int(signed=True)
            patch_hi21(program_data, offs, value // scale + data_section_offset // scale, byteorder)
            print(f"PATCH_OBJECT_HI31 patch_offs=0x{offs:x} mask=0x{mask:x} scale=0x{scale:x} value=0x{value + data_section_offset:x}")
            print(f" | calculated value: 0x{(value // scale + data_section_offset // scale):x}")
        elif com == Command.ENTRY_POINT:
            rel_entr_point = dr.read_int()
            print(f"ENTRY_POINT rel_entr_point=0x{rel_entr_point:x}")
        elif com == Command.RUN_PROG:
            print("RUN_PROG")
        elif com == Command.READ_DATA:
            offs = dr.read_int()
            size = dr.read_int()
            print(f"READ_DATA offs=0x{offs:x} size={size}")
        elif com == Command.FREE_MEMORY:
            print("READ_DATA")
        elif com == Command.DUMP_CODE:
            print("DUMP_CODE")
            end_flag = 2
        elif com == Command.END_COM:
            print("END_COM")
            end_flag = 1
        else:
            assert False, f"Unknown command: {com}"

    with open(output_file, mode='wb') as f_out:
        f_out.write(program_data)

    print(f"Code written to {output_file}.")