For versions up to 3.10 see ./lnotab_notes.txt

In version 3.11 the co_linetable bytes object of code objects contains a compact representation of the positions returned by the co_positions() iterator.

The co_linetable consists of a sequence of location entries. Each entry starts with a byte with the most significant bit set, followed by zero or more bytes with most significant bit unset.

Each entry contains the following information:

• The number of code units covered by this entry (length)
• The start line
• The end line
• The start column
• The end column

The first byte has the following format:

The codes are enumerated in the _PyCodeLocationInfoKind enum.

Integers are often encoded using a variable length integer encoding

Unsigned integers are encoded in 6 bit chunks, least significant first. Each chunk but the last has bit 6 set. For example:

• 63 is encoded as 0x3f
• 200 is encoded as 0x48, 0x03

Signed integers are encoded by converting them to unsigned integers, using the following function:

def convert(s):
    if s < 0:
        return ((-s)<<1) | 1
    else:
        return (s<<1)

The meaning of the codes and the following bytes are as follows:

The Δ means the value is encoded as a delta from another value:

• Start line: Delta from the previous start line, or co_firstlineno for the first entry.
• End line: Delta from the start line

Codes 0-9 are the short forms. The short form consists of two bytes, the second byte holding additional column information. The code is the start column divided by 8 (and rounded down).

• Start column: (code*8) + ((second_byte>>4)&7)
• End column: start_column + (second_byte&15)