bitops – Routines for low-level manipulation of binary data

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bitops.bit_transpose(input: _typing.ReadableBuffer, output: _typing.WriteableBuffer, width: int = 8) → _typing.WriteableBuffer

« Transpose » a buffer by assembling each output byte with bits taken from each of width different input bytes.

This can be useful to convert a sequence of pixel values into a single stream of bytes suitable for sending via a parallel conversion method.

The number of bytes in the input buffer must be a multiple of the width, and the width can be any value from 2 to 8. If the width is fewer than 8, then the remaining (less significant) bits of the output are set to zero.

Let stride = len(input)//width. Then the first byte is made out of the most significant bits of [input[0], input[stride], input[2*stride], ...]. The second byte is made out of the second bits, and so on until the 8th output byte which is made of the first bits of input[1], input[1+stride, input[2*stride], ...].

The required output buffer size is len(input) * 8  // width.

Returns the output buffer.