Ada to D - an array for storing values of each of the six bits which are sufficient

[Dennis Ritchie via Digitalmars-d-learn]

Hi,
There is an array of values to store each of which sufficiently 6 
bits.

As it is written down on the D?

-
With Ada.Text_IO; Use Ada.Text_IO;
With Ada.Integer_Text_IO; Use Ada.Integer_Text_IO;

procedure Program is
type T_Type is range -10 .. 27;
for T_Type'Size use 6;

type Vector is array(1 .. 100) of T_Type;
Pragma Pack(Vector);
My_Array : constant Vector := (1 => -5, 2 => 22, others => 10);

begin
Put_Line(Integer'Image(My_Array'Size));
end Program;
-
http://ideone.com/uAzl41

Re: Ada to D - an array for storing values of each of the six bits which are sufficient

[bearophile via Digitalmars-d-learn]

Dennis Ritchie:

There is an array of values to store each of which sufficiently 
6 bits.

As it is written down on the D?


You can't do it directly in D. Someone has to write a packed 
array data structure to do it.


Bye,
bearophile

Re: Ada to D - an array for storing values of each of the six bits which are sufficient

[Dennis Ritchie via Digitalmars-d-learn]

On Thursday, 30 April 2015 at 11:20:55 UTC, bearophile wrote:

Dennis Ritchie:

There is an array of values to store each of which 
sufficiently 6 bits.

As it is written down on the D?


You can't do it directly in D. Someone has to write a packed 
array data structure to do it.


Bye,
bearophile


Thanks.
Anybody can write a packed array on the D? I once badly represent 
the means by which we can write a packed array. Maybe for this 
you should use core.simd or unions?

Re: Ada to D - an array for storing values of each of the six bits which are sufficient

[bearophile via Digitalmars-d-learn]

Dennis Ritchie:

Anybody can write a packed array on the D? I once badly 
represent the means by which we can write a packed array. Maybe 
for this you should use core.simd or unions?


SIMD could be useful for some fancy bulk operations. But you 
should be able to write a good basic packed array without SIMD, 
perhaps about as nice as the Ada ones (D sometimes offers good 
enough tools to build what you need).


Posible use:

PackedDynamicArray!6 pa; // On heap.
PackedFixedArray!(6, 300) pfa; // On stack.

Bye,
bearophile

Re: Ada to D - an array for storing values of each of the six bits which are sufficient

[Dennis Ritchie via Digitalmars-d-learn]

Maybe someone will show a primitive packed array. I really can 
not imagine how to do it on D.

Re: Ada to D - an array for storing values of each of the six bits which are sufficient

[Dennis Ritchie via Digitalmars-d-learn]

On Friday, 1 May 2015 at 23:22:31 UTC, Dennis Ritchie wrote:
Maybe someone will show a primitive packed array. I really can 
not imagine how to do it on D.


Maybe you can somehow use bitfields. While what happened is 
something like this:


-
import std.stdio, std.bitmanip;

struct A
{
mixin(bitfields!(
uint, "bit",  6,
bool, "flag1", 1,
bool, "flag2", 1));
}


void main() {

A obj;

int[] a;

foreach (e; 0 .. 64) {
obj.bit = e;
a ~= e;
}

writeln(a);

// obj.bit = 64; // Value is greater than
//the maximum value of bitfield 'bit'
}
-
http://ideone.com/Opr4zM

Re: Ada to D - an array for storing values of each of the six bits which are sufficient

[Martin Nowak via Digitalmars-d-learn]

On Friday, 1 May 2015 at 23:22:31 UTC, Dennis Ritchie wrote:
Maybe someone will show a primitive packed array. I really can 
not imagine how to do it on D.


Look at BitArray for an example 
https://github.com/D-Programming-Language/phobos/blob/12187d7be8b15b2f5f8ff6889cdb5ea3afb93dd1/std/bitmanip.d#L702.


Here is an implementation in C++ that could be easily adopted.
http://pempek.net/articles/2013/08/03/bit-packing-with-packedarray/

Re: Ada to D - an array for storing values of each of the six bits which are sufficient

[Dennis Ritchie via Digitalmars-d-learn]

On Sunday, 3 May 2015 at 14:49:55 UTC, Martin Nowak wrote:

On Friday, 1 May 2015 at 23:22:31 UTC, Dennis Ritchie wrote:
Maybe someone will show a primitive packed array. I really can 
not imagine how to do it on D.


Look at BitArray for an example 
https://github.com/D-Programming-Language/phobos/blob/12187d7be8b15b2f5f8ff6889cdb5ea3afb93dd1/std/bitmanip.d#L702.


Here is an implementation in C++ that could be easily adopted.
http://pempek.net/articles/2013/08/03/bit-packing-with-packedarray/


Thank you. This should help.

Re: Ada to D - an array for storing values of each of the six bits which are sufficient

[Dennis Ritchie via Digitalmars-d-learn]

Realized bitmap, sorry that does not work with DMD 2.067.1:

http://vlang.org/docs/Data_Types/Bits_and_Logic.html
https://github.com/coverify/vlang/blob/master/src/esdl/data/bvec.d