A variable-length integer,
in the format used by the 0xfe chunks in the `'dcmp' (0)`

and `'dcmp' (1)`

resource compression formats.
See the dcmp_0 and dcmp_1 specs for more information about these compression formats.

This variable-length integer format can store an integer `x`

in any of the following ways:

- In a single byte,
if
`0 <= x <= 0x7f`

(7-bit unsigned integer) - In 2 bytes,
if
`-0x4000 <= x <= 0x3eff`

(15-bit signed integer with the highest`0x100`

values unavailable) - In 5 bytes, if
`-0x80000000 <= x <= 0x7fffffff`

(32-bit signed integer)

In practice, values are always stored in the smallest possible format, but technically any of the larger formats could be used as well.

This page hosts a formal specification of Variable-length integer used in Apple `'dcmp' (0)` and `'dcmp' (1)` compressed resource formats using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

```
meta:
id: dcmp_variable_length_integer
title: Variable-length integer used in Apple `'dcmp' (0)` and `'dcmp' (1)` compressed resource formats
application: Mac OS
license: MIT
ks-version: "0.8"
endian: be
doc: |
A variable-length integer,
in the format used by the 0xfe chunks in the `'dcmp' (0)` and `'dcmp' (1)` resource compression formats.
See the dcmp_0 and dcmp_1 specs for more information about these compression formats.
This variable-length integer format can store an integer `x` in any of the following ways:
* In a single byte,
if `0 <= x <= 0x7f`
(7-bit unsigned integer)
* In 2 bytes,
if `-0x4000 <= x <= 0x3eff`
(15-bit signed integer with the highest `0x100` values unavailable)
* In 5 bytes, if `-0x80000000 <= x <= 0x7fffffff`
(32-bit signed integer)
In practice,
values are always stored in the smallest possible format,
but technically any of the larger formats could be used as well.
doc-ref: 'https://github.com/dgelessus/python-rsrcfork/blob/f891a6e/src/rsrcfork/compress/common.py'
seq:
- id: first
type: u1
doc: |
The first byte of the variable-length integer.
This determines which storage format is used.
* For the 1-byte format,
this encodes the entire value of the value.
* For the 2-byte format,
this encodes the high 7 bits of the value,
minus `0xc0`.
The highest bit of the value,
i. e. the second-highest bit of this field,
is the sign bit.
* For the 5-byte format,
this is always `0xff`.
- id: more
type:
switch-on: first
cases:
0xff: s4
_: u1
if: first >= 0x80
doc: |
The remaining bytes of the variable-length integer.
* For the 1-byte format,
this is not present.
* For the 2-byte format,
this encodes the low 8 bits of the value.
* For the 5-byte format,
this encodes the entire value.
instances:
value:
value: |
first == 0xff ? more
: first >= 0x80 ? (first << 8 | more) - 0xc000
: first
doc: |
The decoded value of the variable-length integer.
```