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digitalmars.D.learn - Ada to D - an array for storing values of each of the six bits which

reply "Dennis Ritchie" <dennis.ritchie mail.ru> writes:
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
Apr 30 2015
parent reply "bearophile" <bearophileHUGS lycos.com> writes:
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
Apr 30 2015
parent reply "Dennis Ritchie" <dennis.ritchie mail.ru> writes:
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?
May 01 2015
parent reply "bearophile" <bearophileHUGS lycos.com> writes:
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
May 01 2015
parent reply "Dennis Ritchie" <dennis.ritchie mail.ru> writes:
Maybe someone will show a primitive packed array. I really can 
not imagine how to do it on D.
May 01 2015
next sibling parent "Dennis Ritchie" <dennis.ritchie mail.ru> writes:
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
May 02 2015
prev sibling parent reply "Martin Nowak" <code dawg.eu> writes:
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/
May 03 2015
parent reply "Dennis Ritchie" <dennis.ritchie mail.ru> writes:
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.
May 03 2015
parent "Dennis Ritchie" <dennis.ritchie mail.ru> writes:
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
May 05 2015