DOS Binary EPS

create_epsf.py

import struct
import sys

def xor_checksum(data):
    checksum = 0
    for byte in data:
        checksum ^= byte
    return checksum & 0xFFFF

def create_dos_eps(postscript_path, tiff_path, output_path):
    # Read input files
    with open(postscript_path, 'rb') as f:
        ps_data = f.read()

    with open(tiff_path, 'rb') as f:
        tiff_data = f.read()

    padding_size = 4096
    header_size = 30
    ps_start = header_size + padding_size  # PostScript starts after header + padding
    ps_length = len(ps_data)

    metafile_start = 0
    metafile_length = 0

    tiff_start = ps_start + ps_length
    tiff_length = len(tiff_data)

    # Build the header (first 28 bytes)
    header = struct.pack(
        '<I6I',               # little-endian: magic + 6 x 4-byte ints
        0xC6D3D0C5,           # Magic number
        ps_start,             # Start of PostScript section
        ps_length,            # Length of PostScript
        metafile_start,       # Metafile start (unused)
        metafile_length,      # Metafile length
        tiff_start,           # TIFF start
        tiff_length           # TIFF length
    )

    # Compute checksum over bytes 0–27
    checksum = xor_checksum(header)
    header += struct.pack('<H', checksum)  # 28-29: Checksum

    # Total header is now 30 bytes
    assert len(header) == 30

    # Generate 4096 bytes of padding
    padding = b'\x00' * padding_size

    # Write the output file
    with open(output_path, 'wb') as f:
        f.write(header)
        f.write(padding)
        f.write(ps_data)
        f.write(tiff_data)

    print(f'DOS EPS with 4KB padding created: {output_path}')

# Example usage
if __name__ == "__main__":
    if len(sys.argv) != 4:
        print("Usage: python create_dos_eps.py input.ps input.tiff output.eps")
        sys.exit(1)

    ps_file = sys.argv[1]
    tiff_file = sys.argv[2]
    out_file = sys.argv[3]
    create_dos_eps(ps_file, tiff_file, out_file)