As we can construct a bitset object by a Buffer, Can we convert the bitset to Buffer

[blyadav511]

As we can construct a bitset object by a Buffer, Can we convert the bitset to Buffer

let bitset = require("bitset");
let buf = Buffer.from([100, 97, 98]);
let bs = bitset(buf);
bs.toString();
'11000100110000101100100'

Can we convert a bitset into buffer?
let bs1 = new bitset();
bs1.setRange(4,9,1);
{ data: [ 1008, 0, 0, 0, 0, 0, 0, 0, 0, 0 ], _: 0 }
bs1.toString();
'1111110000'

Now can this be converted into the buffer?
eg. add the padding 0's left and make it's size multiple of 8 then convert to byte array or Buffer.

[infusion]

You must note, that this only works for non-negated bitsets. If _ != 0, you must truncate it yourself at a certain point.
For "positive" bitsets (no NOT operation was applied), you could come up with something like

// Remove unnecessary zeros
while (bs.data.length > 1 && bs.data[bs.data.length - 1] === 0) {
   bs.data.pop();
}

// Pad with zeros to a multiple of 8
while (bs.data.length % 8 != 0) {
   bs.data.push(0);
}

const buf = Buffer.from(bs.data.reverse());

If you don't need the minimal multiple of 8, remove the first loop.

[blyadav511]

@infusion,
bs.data is a list of integer and each index of list stores 32 bits. So push/pop operation adds/removes 32 bits from the bitset.

eg.
et bs1 = new bitset();
bs1.setRange(4,9,1); => 1111110000 => 1008
{ data: [ 1008 ] }

bs1.setRange(32,33,1); => 11 00000000000000000000001111110000
{ data: [ 1008, 3 ] }

setRange
bs1.data.push(1);
{ data: [ 1008, 3, 1]}

1 00000000000000000000000000000011 00000000000000000000001111110000

note: bs.toString() removes initial zeros.

[infusion]

bs.data is a list of integer and each index of list stores 32 bits. So push/pop operation adds/removes 32 bits from the bitset.

I know, I designed it like this.

eg.
et bs1 = new bitset();
bs1.setRange(4,9,1); => 1111110000 => 1008
{ data: [ 1008 ] }

bs1.setRange(32,33,1); => 11 00000000000000000000001111110000
{ data: [ 1008, 3 ] }

setRange
bs1.data.push(1);
{ data: [ 1008, 3, 1]}

1 00000000000000000000000000000011 00000000000000000000001111110000

note: bs.toString() removes initial zeros.

I know. What has that to do with your initial question?

[blyadav511]

let bitset = require("bitset");
let buf = Buffer.from([100, 97, 98]);
<Buffer 64 61 62>
buf.toString();

'dab' // contains a string as "dba"

let bs = bitset(buf);
bs.toString();
'11000100110000101100100' // considering each element of buffer as 8 bit

//convert back to buffer
while (bs.data.length > 1 && bs.data[bs.data.length - 1] === 0) {bs.data.pop();}
while (bs.data.length % 8 != 0) {bs.data.push(0);}
let buf2 = Buffer.from(bs.data.reverse());

<Buffer 00 00 00 00 00 00 00 64>
buf2.toString();
'\u0000\u0000\u0000\u0000\u0000\u0000\u0000d'

So we are not getting same buffer... @infusion