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--- simulating_20a_20union [2018/04/17 18:48] – Added syntax highlighting tbest3112
+++ simulating_20a_20union [2024/01/05 00:21] (current) – external edit 127.0.0.1
@@ Line 5: / Line 5: @@
         DIM s1{v%}
         DIM s2{b0&,b1&,b2&,b3&}
-        !(^s2{}+4) = s1{}
+        PTR (s2{)) = PTR(s1{})
         s1.v% = &12345678
@@ Line 11: / Line 11: @@
         PRINT ~s2.b0& s2.b1& s2.b2& s2.b3&
 </code>
-Here the structure **s1{}** contains the 32-bit integer value **s1.v%** and the structure **s2{}** contains the four 8-bit values **s2.b0&**, **s2.b1&**, **s2.b2&** and **s2.b3&**. The third line is a bit of 'magic' which sets **s2{}** to point to the same data as **s1{}**.\\ \\  Hence you can write and read the data using either of the two formats. In the example above the data is written as a single 32-bit value and read as four 8-bit values.\\ \\  If you prefer to hide the non-obvious 'magic' code away from public gaze, you can put it in a procedure (which could even be contained in a library) as follows:\\ \\
+Here the structure **s1{}** contains the 32-bit integer value **s1.v%** and the structure **s2{}** contains the four 8-bit values **s2.b0&**, **s2.b1&**, **s2.b2&** and **s2.b3&**. The third line sets **s2{}** to point to the same data as **s1{}**.\\ \\  Hence you can write and read the data using either of the two formats. In the example above the data is written as a single 32-bit value and read as four 8-bit values.\\ \\
-<code bb4w>
-        DIM s1{v%}
-        DIM s2{b0&,b1&,b2&,b3&}
-        PROCunion(s1{}, s2{})
-        s1.v% = &12345678
-        PRINT ~s2.b0& s2.b1& s2.b2& s2.b3&
-        END
-        DEF PROCunion(a{}, RETURN b{})
-        !(^b{}+4) = a{}
-        ENDPROC
-</code>
 Note that, unlike languages which have true unions, this technique will not save memory. The memory originally allocated to the structure **s2{}** is wasted, but that doesn't matter if it is a LOCAL structure since the memory will be released on exit from the procedure or function in which it was declared.