cbytesparseΒΆ

Utilities for sparse blocks of bytes.

Blocks are a useful way to describe sparse linear data.

The audience of this module are most importantly those who have to manage sparse blocks of bytes, where a very broad addressing space (e.g. 4 GiB) is used only in some sparse parts (e.g. physical memory addressing in a microcontroller).

This module also provides the Memory class, which is a handy wrapper around blocks, giving the user the flexibility of most operations of a bytearray on sparse byte-like chunks.

A block is a tuple (start, data) where start is the start address and data is the container of data items (e.g. bytearray). The length of the block is len(data). Actually, the module uses lists instead of tuples, because the latter are mutables, thus can be changed in-place, without reallocation.

In this module it is common to require spaces blocks, i.e. blocks in which a block b does not start immediately after block a:

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[A

B

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[x

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>>> a = [1, b'ABC']
>>> b = [5, b'xyz']

Instead, overlapping blocks have at least an addressed cell occupied by more items:

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[A

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[x

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[#

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[!]

>>> a = [1, b'ABC']
>>> b = [3, b'xyz']
>>> c = [0, b'##']
>>> d = [2, b'!']

Contiguous blocks are non-overlapping.

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[A

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[x

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>>> a = [1, b'ABC']
>>> b = [4, b'xyz']

This module often deals with sequences of blocks, typically list objects containing blocks:

>>> seq = [[1, b'ABC'], [5, b'xyz']]

Sometimes sequence generators are allowed, in that blocks of the sequence are yielded on-the-fly by a generator, like seq_gen:

>>> seq_gen = ([i, (i + 0x21).to_bytes(1, 'little') * 3] for i in range(0, 15, 5))
>>> list(seq_gen)
[[0, b'!!!'], [5, b'&&&'], [10, b'+++']]

It is required that sequences are ordered, which means that a block b must follow a block a which end address is lesser than the start of b, like in:

>>> a = [1, b'ABC']
>>> b = [5, b'xyz']
>>> a[0] + len(a[1]) <= b[0]
True

cbytesparse.c

Cython implementation.