DIM AT -- feature request

[Jack]

PowerBasic has a very handy feature, the ability to dim at a certain address, for example suppose that you want to use a fixed-length string as a memory buffer
DIM buff As String * 256
DIM m(31) AS _Unsigned Long AT VARPTR(buff)

then you could access the array as usual but the values of the array m would be stored in the string buff
since QB64pe lacks arrays in Type, you could almost have that flexibility if you had Dim At

[mnrvovrfc]

The "DIM" statement presented there looks confusing.

Therefore after many years I'm glad QB64 instead has _MEM and _OFFSET.

I understand, use "m(1), m(2)" etc. to access portions in "buff", but yet this could be simplified with _MEMGET and _MEMPUT wrapped into convenience functions. Because we are all using 64-bit there would be no performance penalty for it.

[grymmjack]

Hi @Jack

I just stumbled onto this in the issue tracker:
https://github.com/QB64-Phoenix-Edition/...1611346466

I ran into a similar issue with my 2d physics engine. What I ended up doing is making the arrays into _MEM's (essentially making it a pointer) and I created some getters and setters to extract my data from the _MEM array.

Here is an example of what I did. You can make "test" and array in itself, however you have to do a _memnew for each element in the array.

Code: (Select All)

TYPE Example

Parameter1 AS INTEGER

Parameter2 AS INTEGER

Parameter3 AS _MEM

END TYPE



DIM test AS Example: test.Parameter3 = _MEMNEW(2 * 10) ' sizeof Integer * Number of elements



setter test, 2, 5

setter test, 6, 3

setter test, 9, 1



PRINT getter(test, 2)

PRINT getter(test, 6)

PRINT getter(test, 9)



SUB setter (test AS Example, index AS LONG, value AS INTEGER)

_MEMPUT test.Parameter3, test.Parameter3.OFFSET + (index * 2), value AS INTEGER

END SUB



FUNCTION getter% (test AS Example, index AS LONG)

getter = _MEMGET(test.Parameter3, test.Parameter3.OFFSET + (index * 2), INTEGER)

END FUNCTION

This might help you as it helped me.