Bit stream library

Introduction

This library was made to make things like decoding / encoding base64 and accessing binary files easier.

New bitstream is created by typing

libbitstream::BitStream bs;
bs.open(/* desired size in bytes */);

The size is in bytes cause the bitstream uses byte arrays to save data.

Bit stream can also be created from an existing byte array.

libbitstream::BitStream bs;
bs.openBytes(/* array pointer */, /* array size */);

You can also construct the bitstream object directly.

libbitstream::BitStream bs(/* desired size in bytes */);
// OR
libbitstream::BitStream bs(/* array pointer */, /* array size */);

After opening bitstream and working with it can be closed by doing typing

bs.close();

Closing a bitstream frees memory that was allocated to create it.

If you created the bitstream by opening an array then closing the bitstream will free memory allocated for the array.

To read from bitstream you type

bs.read(/* index (in bits) */, /* size (in bits) */);

and to write to bitstream use

bs.write(/* index (int bits) */, /* size (in bits) */, /* an integer (a value) */);

size must be smaller than 32 bits and the value is an integer.

If we have the following bitstream

0 0 0 1 1 0 1 1

and we type

bs.write(0, 4, 11); // 11 = binary 1011

we will get

written value
   |
+--+--+
1 0 1 1 1 0 1 1

If you are tracking a bitstream and want to write alignment bits at a certain position to align the bitstream to a byte, you can do this:

pos = writeAlignBits(/* index (int bits) */);

It will write zero bits until the beginning of the next byte, then return the position.

Also, it works for reading a bitstream:

pos = readAlignBits(/* index (int bits) */);

It will return next byte's position, without writing anything.

To turn the bitstream to a byte array type:

bs.toByteArray(); // returns a char* pointer (when changes are made to the bitstream using bs.write, the returned array will also change)

Original author: FranX1024 on project FranX1024/bitstream at 2019.

Forked and modified by: izwb003 at 2024.

Can be used freely without any license. But no guarantee or warranty is provided.