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aligning_20structures [2018/04/17 15:01]
tbest3112 Added syntax highlighting
aligning_20structures [2021/12/04 16:05] (current)
richardrussell Modified for 64-bit compatibility
Line 6: Line 6:
 <code bb4w> <code bb4w>
         DIM mystruct{member1,​ member2, etc, padding%}         DIM mystruct{member1,​ member2, etc, padding%}
-        ​!(^mystruct{}+4) = (mystruct{}+4) AND -8+        ​PTR(mystruct{}) = PTR(mystruct{}) AND -8
 </​code>​ </​code>​
 When the structure is declared, a dummy member **padding%** is added at the very end; this allows the structure to be moved up in memory by 4 bytes, if necessary, without corrupting subsequent memory contents; //it is vitally important that this member is never written//! The second line adjusts the address of the structure so that it is a multiple of eight.\\ \\  If you want to align the structure at a multiple-of-16 address the padding needs to be 12 bytes in size, most easily arranged by making it an array:​\\ ​ When the structure is declared, a dummy member **padding%** is added at the very end; this allows the structure to be moved up in memory by 4 bytes, if necessary, without corrupting subsequent memory contents; //it is vitally important that this member is never written//! The second line adjusts the address of the structure so that it is a multiple of eight.\\ \\  If you want to align the structure at a multiple-of-16 address the padding needs to be 12 bytes in size, most easily arranged by making it an array:​\\ ​
 <code bb4w> <code bb4w>
         DIM mystruct{member1,​ member2, etc, padding%(2)}         DIM mystruct{member1,​ member2, etc, padding%(2)}
-        ​!(^mystruct{}+4) = (mystruct{}+12) AND -16+        ​PTR(mystruct{}) = PTR(mystruct{}) AND -16
 </​code>​ </​code>​
 \\  \\ 
Line 19: Line 19:
         DIM mystruct{member1,​ member2, etc}         DIM mystruct{member1,​ member2, etc}
         DIM newdata% DIM(mystruct{})+6         DIM newdata% DIM(mystruct{})+6
-        ​!(^mystruct{}+4) = (newdata%+7) AND -8+        ​PTR(mystruct{}) = (newdata%+7) AND -8
 </​code>​ </​code>​
 Similarly to align it on a multiple-of-16 address:​\\ ​ Similarly to align it on a multiple-of-16 address:​\\ ​
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         DIM mystruct{member1,​ member2, etc}         DIM mystruct{member1,​ member2, etc}
         DIM newdata% DIM(mystruct{})+14         DIM newdata% DIM(mystruct{})+14
-        ​!(^mystruct{}+4) = (newdata%+15) AND -16+        ​PTR(mystruct{}) = (newdata%+15) AND -16
 </​code>​ </​code>​
 Note that you must declare the structure using this method **only once** and not repeat the above code (for example in a loop).\\ \\  If declaring a structure for local use in a procedure or function, use **DIM LOCAL**:​\\ ​ Note that you must declare the structure using this method **only once** and not repeat the above code (for example in a loop).\\ \\  If declaring a structure for local use in a procedure or function, use **DIM LOCAL**:​\\ ​
Line 32: Line 32:
         DIM mystruct{member1,​ member2, etc}         DIM mystruct{member1,​ member2, etc}
         DIM newdata% LOCAL DIM(mystruct{})+6         DIM newdata% LOCAL DIM(mystruct{})+6
-        ​!(^mystruct{}+4) = (newdata%+7) AND -8+        ​PTR(mystruct{}) = (newdata%+7) AND -8
 </​code>​ </​code>​
aligning_20structures.txt ยท Last modified: 2021/12/04 16:05 by richardrussell