Bit array implementation
This module implements a simple BitArray object which consists of a regular seq[uint8] and a pos.
There are 2 main procedures, one to add more bits to the BitArray, add, and another to skip to the next byte, nextByte.
For ease of use there are some templates to help write less code, like [], so instead of writing myBitArray.data[i] you would write myBitArray[i], as if BitArray was a regular seq[uint8].
Types
BitArray = object pos*: uint16 data*: seq[uint8]
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A BitArray object used by EncodedQRCode.
pos is used to keep track of where new bits will be placed.
Source Edit
Procs
func add(self: var BitArray; val: SomeUnsignedInt; len: uint8)
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Add len amount of bits from val starting from the rightmost bit.
Example:
var myBitArray = newBitArray(1) myBitArray.add 0b110011'u8, 4 # should add 0011, not 110011 assert myBitArray[0] == 0b0011_0000 # ^ pos will be here
Source Edit func newBitArray(size: uint16): BitArray {....raises: [], tags: [].}
- Creates a new BitArray object whose data will have a cap of size and it's len will also be set to size. Source Edit
func nextByte(self: var BitArray): uint8 {....raises: [], tags: [].}
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Moves pos to the next byte, unless it is pointing to the start of an empty byte.
Example:
myBitArray.data: 0101_0110, 1010_0000, 0000_0000 ^ pos points here after using nextByte(): myBitArray.data: 0101_0110, 1010_0000, 0000_0000 ^ pos points hereSource Edit
Templates
template `[]=`(self: var BitArray; i: SomeInteger; val: uint8)
- Set the value of data in index i to val. Source Edit
template `[]`[T, S](self: BitArray; i: HSlice[T, S]): seq[uint8]
- Get the values of data in the slice i. Source Edit
template len(self: BitArray): int
- Get the len of self.data. Used nstead of writing data.data.len in other modules. Source Edit
template unsafeAdd(self: var BitArray; val: uint8)
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Add val to the end of data.Warning: This is unsafe since, by default, data's len is set to it's max capacity and pos is not updated.Source Edit
template unsafeDelete(self: var BitArray; pos: uint16)
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Remove the value from data in position pos.Warning: This is unsafe since pos is not updated.Source Edit