Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

2018-03-06 12:06 GMT-03:00 Henrik Sperre Johansen : > Esteban A. Maringolo wrote > BaseX encode/decode can be simple enough to fit in a small workspace: > > base := 58. > base58Lookup := > '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'. > myNumber :=

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

Esteban A. Maringolo wrote > Hi Richard, > > Certainly a BitStream is beyond what I initially thought. > > But it could be of some use to play with it, is it available somewhere > with a friendly open source license? > > I might give it a try using it for my generator (tests are already >

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

+100. Strings are "dead bits", lacking behaviour specific to what they represent. Your date example is an excellent portrayal of that. They should never be used for holding structured data. Think of strings (dead bits) in much the same way we think of paper (dead trees). On Mar 6, 2018

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

Re "Strings are wrong", the influences on my thinking went like this. (1) As an undergraduate, I did exercises with the Euler compiler (written in Burroughs Algol) and the XPL compiler (written in XPL). XPL had immutable strings, rather like AWK or Java, and a PL/I-ish set of

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

Hi Richard, Certainly a BitStream is beyond what I initially thought. But it could be of some use to play with it, is it available somewhere with a friendly open source license? I might give it a try using it for my generator (tests are already passing). Your example is almost complete, but if

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

I note that the specification in question does not deal with arbitrary bit strings but with "entropies" that are 128 to 256 bits long and a multiple of 32 bits. 4 to 8 bits are copied from the front to the end. (So selecting *this* bit field can be done by taking the first byte of a ByteArray.)

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

2018-03-05 14:02 GMT-03:00 Stephane Ducasse : > On Sun, Mar 4, 2018 at 9:43 PM, Esteban A. Maringolo > wrote: >> 2018-03-04 17:15 GMT-03:00 Sven Van Caekenberghe : >>> Bits are actually numbered from right to left (seen from how they

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

2018-03-05 10:52 GMT-03:00 Richard O'Keefe : > As I understand it, the OP's problem is that he wants to > count bits from the high end, and Integers don't *have* > a finite high end. Exactly. I want to work with a block of bits, today the best proxy for that is using an

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

On Mon, Mar 5, 2018 at 2:52 PM, Richard O'Keefe wrote: > ​As I understand it, the OP's problem is that he wants to > count bits from the high end, and Integers don't *have* > a finite high end. > > PL/I has bit strings. Common Lisp has bit strings. > Some Schemes have copied

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

It looks like having BitArray is a good approach. Is there a MIT compatible version? I could add it to my collection collection :) Containers I should migrate it to github. Stef On Mon, Mar 5, 2018 at 2:52 PM, Richard O'Keefe wrote: > As I understand it, the OP's problem is

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

On Sun, Mar 4, 2018 at 9:43 PM, Esteban A. Maringolo wrote: > 2018-03-04 17:15 GMT-03:00 Sven Van Caekenberghe : >> Bits are actually numbered from right to left (seen from how they are >> printed). > > I understand bit operations, used it extensively with IP

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

​As I understand it, the OP's problem is that he wants to count bits from the high end, and Integers don't *have* a finite high end. PL/I has bit strings. Common Lisp has bit strings. Some Schemes have copied Lisp. Eiffel _had_ bit strings, more or less, but dropped them. Smalltalk/X has a

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

--- Begin Message --- Just put that in Integer. bitsSliceFrom: start to: end     "     Extract bits 4 to 6, i.e. 111 which equals to 7     2r1111000 bitsSliceFrom: 4 to: 6     "     | num mask  |     self < 0 ifTrue: [self error: 'This operation is not allowed for

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

--- Begin Message --- Hi Esteban, When you say "extract", what exactly do you mean? Let's suppose you have 86, i.e. 2r1010110 Which case do you want? a) 2r1010110 "2 to 5 = 2r10[1011]0 = 2r1011 = 11" or b) 2r1010110 "2 to 5 = 2r10[1011]0 = 2r00[1011]0 =  2r0010110 =  22" Both cases can be

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

Please, if you do implement something, start with a Collection class and call it something like BitArray. It might be appropriate to subclass under ByteArray, but perhaps not. On Mar 4, 2018 12:45 PM, "Esteban A. Maringolo" wrote: > 2018-03-04 17:15 GMT-03:00 Sven Van

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

2018-03-04 17:15 GMT-03:00 Sven Van Caekenberghe : > Bits are actually numbered from right to left (seen from how they are > printed). I understand bit operations, used it extensively with IP address eons ago. But if a spec says: "Take the first n bits from the hash", it means the

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

Bits are actually numbered from right to left (seen from how they are printed). But in a fixed amount of bits you could indeed number them the other way around. It does not matter that you write the leading zeros or not, everything to the left is zero anyway. When shifting, the right thing

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

I do bitshifts and masks on Integer. What if you want to take the bits from the 3rd to the 7th? You have to do a some arithmetic to get the slice you want. I'm simply asking for something more dev-friendlier that adds a "layer" on top of that, but that internally does regular bitwise. What I

Re: [Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

Take a 24-bit number and you want to isolate the first 5 (these are actually the last, higher order) bits. n := 2r10101000. n >> (16+3). If necessary, you can apply a mask (assume there are bits earlier/later still). (n >> (16+3)) bitAnd: 2r1 Large integers behave as bit

[Pharo-users] Bitwise operations in ByteArray (slicing, etc.)

Is there any package/library that makes bitwise operations as simple as with an Integer, but for larger numbers (as in a ByteArray). Something that allows me to "slice" a sequence of bits, or extract some using the same protocol as with a String of ones and zeros. Now when I need to work with