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Re: [Pharo-project] how can I get bit representation of numbers

by StÃ©phane Ducasse

What I'm looking for is a way to explain/understand simply how SmallInteger are implemented. >> Two's complement is a platform representation of integers not (necessarily) a smalltalk one. The concept of negative numbers has nothing to do with the radix a number is expressed in. Yes I learned that >> >> There are convenient extensions to the ByteArray protocol added by FFI which allow easy conversion though. I don't have time this second to list them, but will do so in a few hours. > > That's true, but the internal implementation leaks out the bitAnd: > bitOr: and other bit operations... I want to explain two's complement then Smalltalk smallinteger \section{Two's complement of a number} .... Creating a two complement version of a number equals negating the number bits and adding one. \begin{code}{Calculating two complement of 3} 3 bitString '0000000000000000000000000000011' 3 bitInvert bitString '1111111111111111111111111111100' (3 bitInvert + 1) bitString '1111111111111111111111111111101' -3 bitString '1111111111111111111111111111101' \end{code} .... \section{SmallIntegers in Smalltalk} Smalltalk small integers uses a two's complement arithmetic on 31 bits. An N-bit two's-complement numeral system can represent every integer in the range $-1 * 2^{N-1}\ to\ 2^{N-1}-1$. So for 32 bits Smalltalk systems, small integers values are the range -1073741824 to 1073741823. Let's check that a bit (this is the occasion to say it). \begin{code}{} 2 raisedTo: 29 returns 536870912 536870912 class returns SmallInteger 2 raisedTo: 30 returns 1073741824 1073741824 class returns LargePositiveInteger -1073741824 class returns SmallInteger 2 class maxVal returns 1073741823 -1 * (2 raisedTo: (31-1)) returns -1073741824 (2 raisedTo: 30) - 1 returns 1073741823

July 5, 2011

[Pharo-project] "I arranged all my public packages with metacello."

by HwaJong Oh

Hi, I arranged all my public packages with metacello. http://www.squeaksource.com/DaliotsPlayground.html What i did was: step 0. learned metacello with ProStef (ProStef rocks!) step 1. create a new repository www.squeaksource.com/DaliotsPlayground. step 2. upload all public packages to it. (Gofer push rocks!) step 3. With clean image, test each packages installable stand-aone. step 4. Write small ConfigurationOfXXX package for each package that does not install alone. step 5. realize all those small ConfigurationOfXXX have many redundancy. step 6. create ConfigurationOfDaliotsPlayground and copied baselines and versions into it. step 7. removed all ConfigurationOfXXX except ConfigurationOfDaliotsPlayground. ** through this process, tested each packages and ConfigurationOfXXXs by installing them in clearn image. problems: 1. package testing was uneffiicient consuming a lot of time. 2. download counts and activity indicator soared unintentionally. 3. testing doubles since Squeak compatibility is not checked. Best Regards -- View this message in context: http://forum.world.st/I-arranged-all-my-public-packages-with-metacello-tp36… Sent from the Pharo Smalltalk mailing list archive at Nabble.com.

July 5, 2011

Re: [Pharo-project] how can I get bit representation of numbers

by Nicolas Cellier

2011/7/5 Douglas McPherson <djm1329(a)san.rr.com>: > Two's complement is a platform representation of integers not (necessarily) a smalltalk one. The concept of negative numbers has nothing to do with the radix a number is expressed in. > > There are convenient extensions to the ByteArray protocol added by FFI which allow easy conversion though. I don't have time this second to list them, but will do so in a few hours. > > That's true, but the internal implementation leaks out the bitAnd: bitOr: and other bit operations... Nicolas > > On Jul 4, 2011, at 15:14 , StÃ©phane Ducasse wrote: > >> Sven do your code work with Smalltalk smallInteger? >> Because I think that in that case you should have 31 bits? >> >> >>>> I would like to see the two complement representation of numbers. >>> >>> This is what I do, for reading/writing unsigned or two complement signed integer from/to byte streams. >>> >>> Note that two complement is only defined for a specific number size, 8, 16, 32 bits. >>> >>> unsignedToSigned: integer size: size >>> Â Â Â ^ integer < (2 raisedTo: size - 1) >>> Â Â Â Â Â Â Â ifTrue: [ integer ] >>> Â Â Â Â Â Â Â ifFalse: [ (self twoComplement: integer size: size) negated ] >>> >>> signedToUnsigned: integer size: size >>> Â Â Â ^ integer negative >>> Â Â Â Â Â Â Â ifTrue: [ self twoComplement: integer size: size ] >>> Â Â Â Â Â Â Â ifFalse: [ integer ] >>> >>> twoComplement: integer size: size >>> Â Â Â | mask | >>> Â Â Â mask := (2 raisedTo: size) - 1. >>> Â Â Â ^ mask bitAnd: ((integer abs bitXor: mask) + 1) >>> >>> These are also very handy in this context (I believe I once submitted that as an issue): >>> >>> integerFromByteArray: bytes >>> Â Â Â | integer | >>> Â Â Â integer := 0. >>> Â Â Â bytes withIndexDo: [ :each :index | >>> Â Â Â Â Â Â Â integer := integer + (each bitShift: (bytes size - index) * 8) ]. >>> Â Â Â ^ integer >>> >>> and Integer>>#asByteArrayOfSize: >>> >>> Once you have a byte representation, you can render it as bits as well. >>> >>> Sven >>> >>> >>> >> >> > > >

July 4, 2011

Re: [Pharo-project] how can I get bit representation of numbers

by Douglas McPherson

Two's complement is a platform representation of integers not (necessarily) a smalltalk one. The concept of negative numbers has nothing to do with the radix a number is expressed in. There are convenient extensions to the ByteArray protocol added by FFI which allow easy conversion though. I don't have time this second to list them, but will do so in a few hours. On Jul 4, 2011, at 15:14 , StÃ©phane Ducasse wrote: > Sven do your code work with Smalltalk smallInteger? > Because I think that in that case you should have 31 bits? > > >>> I would like to see the two complement representation of numbers. >> >> This is what I do, for reading/writing unsigned or two complement signed integer from/to byte streams. >> >> Note that two complement is only defined for a specific number size, 8, 16, 32 bits. >> >> unsignedToSigned: integer size: size >> ^ integer < (2 raisedTo: size - 1) >> ifTrue: [ integer ] >> ifFalse: [ (self twoComplement: integer size: size) negated ] >> >> signedToUnsigned: integer size: size >> ^ integer negative >> ifTrue: [ self twoComplement: integer size: size ] >> ifFalse: [ integer ] >> >> twoComplement: integer size: size >> | mask | >> mask := (2 raisedTo: size) - 1. >> ^ mask bitAnd: ((integer abs bitXor: mask) + 1) >> >> These are also very handy in this context (I believe I once submitted that as an issue): >> >> integerFromByteArray: bytes >> | integer | >> integer := 0. >> bytes withIndexDo: [ :each :index | >> integer := integer + (each bitShift: (bytes size - index) * 8) ]. >> ^ integer >> >> and Integer>>#asByteArrayOfSize: >> >> Once you have a byte representation, you can render it as bits as well. >> >> Sven >> >> >> > >

July 4, 2011

Re: [Pharo-project] how can I get bit representation of numbers

by Nicolas Cellier

For positive integers, we have an infinite serie of 0 bits, but we don't care, we just don't print them. The problem with two complement is that you have an infinite serie of leading 1 bits... Otherwise, you can access the bit at any rank with bitAt: For example, you could use bitRepresentation ^(self digitLength * 8 + 1 to: 1 by: -1) collect: [:i | Character value: $0 charCode + (self bitAt: i)] as: String The first bit will aways be the sign with the + 1 trick. Nicolas 2011/7/4 Sven Van Caekenberghe <sven(a)beta9.be>: > > On 04 Jul 2011, at 20:16, StÃ©phane Ducasse wrote: > >> I would like to see the two complement representation of numbers. > > This is what I do, for reading/writing unsigned or two complement signed integer from/to byte streams. > > Note that two complement is only defined for a specific number size, 8, 16, 32 bits. > > unsignedToSigned: integer size: size > Â Â Â Â ^ integer < (2 raisedTo: size - 1) > Â Â Â Â Â Â Â Â ifTrue: [ integer ] > Â Â Â Â Â Â Â Â ifFalse: [ (self twoComplement: integer size: size) negated ] > > signedToUnsigned: integer size: size > Â Â Â Â ^ integer negative > Â Â Â Â Â Â Â Â ifTrue: [ self twoComplement: integer size: size ] > Â Â Â Â Â Â Â Â ifFalse: [ integer ] > > twoComplement: integer size: size > Â Â Â Â | mask | > Â Â Â Â mask := (2 raisedTo: size) - 1. > Â Â Â Â ^ mask bitAnd: ((integer abs bitXor: mask) + 1) > > These are also very handy in this context (I believe I once submitted that as an issue): > > integerFromByteArray: bytes > Â Â Â Â | integer | > Â Â Â Â integer := 0. > Â Â Â Â bytes withIndexDo: [ :each :index | > Â Â Â Â Â Â Â Â integer := integer + (each bitShift: (bytes size - index) * 8) ]. > Â Â Â Â ^ integer > > and Integer>>#asByteArrayOfSize: > > Once you have a byte representation, you can render it as bits as well. > > Sven > > > >

July 4, 2011

Re: [Pharo-project] how can I get bit representation of numbers

by StÃ©phane Ducasse

Sven do your code work with Smalltalk smallInteger? Because I think that in that case you should have 31 bits? >> I would like to see the two complement representation of numbers. > > This is what I do, for reading/writing unsigned or two complement signed integer from/to byte streams. > > Note that two complement is only defined for a specific number size, 8, 16, 32 bits. > > unsignedToSigned: integer size: size > ^ integer < (2 raisedTo: size - 1) > ifTrue: [ integer ] > ifFalse: [ (self twoComplement: integer size: size) negated ] > > signedToUnsigned: integer size: size > ^ integer negative > ifTrue: [ self twoComplement: integer size: size ] > ifFalse: [ integer ] > > twoComplement: integer size: size > | mask | > mask := (2 raisedTo: size) - 1. > ^ mask bitAnd: ((integer abs bitXor: mask) + 1) > > These are also very handy in this context (I believe I once submitted that as an issue): > > integerFromByteArray: bytes > | integer | > integer := 0. > bytes withIndexDo: [ :each :index | > integer := integer + (each bitShift: (bytes size - index) * 8) ]. > ^ integer > > and Integer>>#asByteArrayOfSize: > > Once you have a byte representation, you can render it as bits as well. > > Sven > > >

July 4, 2011

Re: [Pharo-project] About HTTP

by StÃ©phane Ducasse

curl -i http://localhost:8080/DateOfTheDay|more Stef On Jul 4, 2011, at 5:21 PM, Sven Van Caekenberghe wrote: > > On 02 Jul 2011, at 12:15, StÃ©phane Ducasse wrote: > >> Tx I will look at ZnClient and see if I understand. > > If this is not a sensitive API, you could give me some of the curl calls that you did, and I will quickly translate them to Zinc. > > Sven > >

July 4, 2011

[Pharo-project] fuel configuration was broken

by Tudor Girba

Hi, The Moose build fails because the Fuel configuration is broken. In particular, in baseline15: there was an error because FuelWithProgressBarBenchmarks was not defined anymore, but it was required. So, I simply removed the requirement. Martin, please take a look. Please pay attention when building a new version in a Metacello configuration because Metacello tries to reify every version in the Configuration, even if that version is not used. I keep on arguing that this is not a good thing, but at the moment we have to pay more attention :). Cheers, Doru -- www.tudorgirba.com "Live like you mean it."

July 4, 2011

Re: [Pharo-project] how can I get bit representation of numbers

by Sven Van Caekenberghe

On 04 Jul 2011, at 20:16, StÃ©phane Ducasse wrote: > I would like to see the two complement representation of numbers. This is what I do, for reading/writing unsigned or two complement signed integer from/to byte streams. Note that two complement is only defined for a specific number size, 8, 16, 32 bits. unsignedToSigned: integer size: size ^ integer < (2 raisedTo: size - 1) ifTrue: [ integer ] ifFalse: [ (self twoComplement: integer size: size) negated ] signedToUnsigned: integer size: size ^ integer negative ifTrue: [ self twoComplement: integer size: size ] ifFalse: [ integer ] twoComplement: integer size: size | mask | mask := (2 raisedTo: size) - 1. ^ mask bitAnd: ((integer abs bitXor: mask) + 1) These are also very handy in this context (I believe I once submitted that as an issue): integerFromByteArray: bytes | integer | integer := 0. bytes withIndexDo: [ :each :index | integer := integer + (each bitShift: (bytes size - index) * 8) ]. ^ integer and Integer>>#asByteArrayOfSize: Once you have a byte representation, you can render it as bits as well. Sven

July 4, 2011

Re: [Pharo-project] [TODO 1.3] Last items to be done this week...

by Sven Van Caekenberghe

On 04 Jul 2011, at 22:52, Esteban Lorenzano wrote: > yes... I'm aware of the graphics problem, but I still don't know what is causing it (it not happens with pharo 1.2 or squeak, so I think is a combination of "something" in vm side -cocoa version, that "something" in pharo changes brought to front). I will work on that some time this week :) Thanks for all the efforts, Esteban! Sven

July 4, 2011