Oxygen Basic

Information => Development => Topic started by: Brian Alvarez on December 25, 2018, 12:34:05 AM

Title: Unions
Post by: Brian Alvarez on December 25, 2018, 12:34:05 AM

Would this:

Code: [Select]

UNION RECT
    nLeft   AS LONG
    nTop    AS LONG
    nRight  AS LONG
    nBottom AS LONG
    =
    Left   AS LONG
    Top    AS LONG
    Right  AS LONG
    Bottom AS LONG
END UNION
Be how this code:

Code: [Select]

TYPE RECT_old
    nLeft   AS LONG
    nTop    AS LONG
    nRight  AS LONG
    nBottom AS LONG
END TYPE

TYPE RECT_new
    Left   AS LONG
    Top    AS LONG
    Right  AS LONG
    Bottom AS LONG
END TYPE

UNION RECT
    RECT_old
    RECT_new
END UNION
Should be converted?

Title: Re: Unions
Post by: Charles Pegge on December 25, 2018, 02:59:46 AM

Yes, Brian

'=' resets the offset tally, and can be used more than once.

Title: Re: Unions
Post by: Brian Alvarez on December 25, 2018, 12:28:24 PM

I understand.

 Now i needed to add a union to a TYPE (Windows API required it), the offset should not be reset to zero, it is supposed to only reset back to the previous member offset.
I got this already working with low level methods, handling the offsets myself, but is this done already in oxygen? Maybe you could add something like:

Code: [Select]

TYPE RECT
    LONG A
    LONG B
  *             ' Save the offset
    LONG C
    LONG D
  <            ' Go back to saved offset
    LONG E
    LONG F
END TYPE
This way A and B are part of the UDT while E and F overlaps C and D. This would allow to add UNIONS to TYPES.

The number of nested UNIONS in TYPES are undetermined, so, maybe if you decide to do this, the * can also have an ID for example:

Code: [Select]

TYPE RECT
    LONG A
    LONG B
  * 1            ' Save the offset 1
    LONG C
    LONG D
  < 1           ' Go back to saved offset 1
    LONG E
    LONG F
  * 2            ' Save the offset 2
    LONG G
    LONG H
  < 2           ' Go back to saved offset 2
    LONG I
    LONG J
  < 1           ' Go back to saved offset 1
END TYPE
No offset ID would default to 1.

Title: Re: Unions
Post by: Charles Pegge on December 25, 2018, 08:11:59 PM

How about using '+'  to fix the base offset for the next bunch of unions:

Code: [Select]

type omni
  int attrib        'offset 0
  +
  float fx,fy,fz    'offsets 4 8 12
  =
  double dx,dy,dz   'offsets 8 16 24
  =
  int ix,iy,iz      'offsets 4 8 12
  +
  int flags         'offset 32
end type


I can  implement this very easily

Title: Re: Unions
Post by: Brian Alvarez on December 25, 2018, 08:27:21 PM

Im not sure i follow you... take a look at this (correct) example i have right now:

Code: [Select]

UNION UNION1
    C AS QUAD ' Offset 8
    D AS QUAD ' Offset 8
END UNION

UNION UNION2
    E AS QUAD ' Offset 16
    F AS QUAD ' Offset 16
END UNION

TYPE UDT1
    A AS LONG  ' Offset 0
    B AS LONG  ' offset 4
    UNION1
    UNION2
    G AS LONG  ' Offset 24
    H AS LONG  ' Offset 28
END TYPE   

LOCAL U AS UDT1

These are the offsets for all the members of U.

Title: Re: Unions
Post by: Charles Pegge on December 25, 2018, 08:41:23 PM

These structures could be merged into one, by using '+' and '=':

Code: [Select]

TYPE UDT1
    A AS LONG  ' Offset 0
    B AS LONG  ' offset 4
    +
    C AS QUAD ' Offset 8
    =
    D AS QUAD ' Offset 8
    +
    E AS QUAD ' Offset 16
    =
    F AS QUAD ' Offset 16
    +
    G AS LONG  ' Offset 24
    H AS LONG  ' Offset 28
END TYPE   


Title: Re: Unions
Post by: Brian Alvarez on December 25, 2018, 08:46:06 PM

Perfect. Let's do it! :)

Title: Re: Unions
Post by: jack on December 26, 2018, 05:28:59 AM

hello Brian Alvarez, Charles Pegge
would you be willing to make a mini-tutorial on unions for dummies?
the concepts presented here are way over my head, using + and = in a union are foreign to me and I got lost trying to keep track of the offsets

Title: Re: Unions
Post by: Charles Pegge on December 26, 2018, 10:08:11 AM

Hello Jack,

Taking a variant as one of the more extreme examples:

c++

Code: C++

1. typedef struct tagVARIANT {
2.   union {
3.     struct {
4.       VARTYPE vt;
5.       WORD    wReserved1;
6.       WORD    wReserved2;
7.       WORD    wReserved3;
8.       union {
9.         LONGLONG     llVal;
10.         LONG         lVal;
11.         BYTE         bVal;
12.         SHORT        iVal;
13.         FLOAT        fltVal;
14.         DOUBLE       dblVal;
15.         VARIANT_BOOL boolVal;
16.         SCODE        scode;
17.         CY           cyVal;
18.         DATE         date;
19.         BSTR         bstrVal;
20.         IUnknown     *punkVal;
21.         IDispatch    *pdispVal;
22.         SAFEARRAY    *parray;
23.         BYTE         *pbVal;
24.         SHORT        *piVal;
25.         LONG         *plVal;
26.         LONGLONG     *pllVal;
27.         FLOAT        *pfltVal;
28.         DOUBLE       *pdblVal;
29.         VARIANT_BOOL *pboolVal;
30.         SCODE        *pscode;
31.         CY           *pcyVal;
32.         DATE         *pdate;
33.         BSTR         *pbstrVal;
34.         IUnknown     **ppunkVal;
35.         IDispatch    **ppdispVal;
36.         SAFEARRAY    **pparray;
37.         VARIANT      *pvarVal;
38.         PVOID        byref;
39.         CHAR         cVal;
40.         USHORT       uiVal;
41.         ULONG        ulVal;
42.         ULONGLONG    ullVal;
43.         INT          intVal;
44.         UINT         uintVal;
45.         DECIMAL      *pdecVal;
46.         CHAR         *pcVal;
47.         USHORT       *puiVal;
48.         ULONG        *pulVal;
49.         ULONGLONG    *pullVal;
50.         INT          *pintVal;
51.         UINT         *puintVal;
52.         struct {
53.           PVOID       pvRecord;
54.           IRecordInfo *pRecInfo;
55.         } __VARIANT_NAME_4;
56.       } __VARIANT_NAME_3;
57.     } __VARIANT_NAME_2;
58.     DECIMAL decVal;
59.   } __VARIANT_NAME_1;
60. } VARIANT;
61.  

With '=' and '+' notation, and some reorganising, the variant struct can be simplified to something more comprehensible:

Code: OxygenBasic

1. typedef struct tagVARIANT {
2.   DECIMAL decVal
3.   =
4.   VARTYPE vt;
5.   WORD    wReserved1;
6.   WORD    wReserved2;
7.   WORD    wReserved3;
8.   +
9.   PVOID       pvRecord
10.   IRecordInfo *pRecInfo
11.   =
12.   LONGLONG     llVal
13.   =
14.   LONG         lVal
15.   =
16.   BYTE         bVal
17.   =
18.   SHORT        iVal
19.   =
20.   FLOAT        fltVal
21.   =
22.   DOUBLE       dblVal
23.   =
24.   VARIANT_BOOL boolVal
25.   =
26.   SCODE        scode
27.   =
28.   CY           cyVal
29.   =
30.   DATE         date
31.   =
32.   BSTR         bstrVal
33.   =
34.   IUnknown     *punkVal
35.   =
36.   IDispatch    *pdispVal
37.   =
38.   SAFEARRAY    *parray
39.   =
40.   BYTE         *pbVal
41.   =
42.   SHORT        *piVal
43.   =
44.   LONG         *plVal
45.   =
46.   LONGLONG     *pllVal
47.   =
48.   FLOAT        *pfltVal
49.   =
50.   DOUBLE       *pdblVal
51.   =
52.   VARIANT_BOOL *pboolVal
53.   =
54.   SCODE        *pscode
55.   =
56.   CY           *pcyVal
57.   =
58.   DATE         *pdate
59.   =
60.   BSTR         *pbstrVal
61.   =
62.   IUnknown     **ppunkVal
63.   =
64.   IDispatch    **ppdispVal
65.   =
66.   SAFEARRAY    **pparray
67.   =
68.   VARIANT      *pvarVal
69.   =
70.   PVOID        byref
71.   =
72.   CHAR         cVal
73.   =
74.   USHORT       uiVal
75.   =
76.   ULONG        ulVal
77.   =
78.   ULONGLONG    ullVal
79.   =
80.   INT          intVal
81.   =
82.   UINT         uintVal
83.   =
84.   DECIMAL      *pdecVal
85.   =
86.   CHAR         *pcVal
87.   =
88.   USHORT       *puiVal
89.   =
90.   ULONG        *pulVal
91.   =
92.   ULONGLONG    *pullVal
93.   =
94.   INT          *pintVal
95.   =
96.   UINT         *puintVal
97. end type
98.  

Title: Re: Unions
Post by: jack on December 26, 2018, 01:28:12 PM

thank you Charles Pegge :)
it will take some time study this nice example.

Title: Re: Unions
Post by: Brian Alvarez on December 26, 2018, 03:05:00 PM

Charles said it all, and i think a VARIANT is a perfect example of use for unions. :)