Difference between revisions of "Absolute"

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(initial text)
(note little endian)
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<syntaxhighlight>
 
<syntaxhighlight>
// Example on x64 processor
+
// Example on little endian x64 processor
 
Uses SysUtils;
 
Uses SysUtils;
  
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     // 333 is too large a value to fit in one byte
 
     // 333 is too large a value to fit in one byte
     // 333 = 101001101 = 00000001 01001101 = 1 77
+
    // little-endian x64 - least significant byte is first in memory:
 +
     // 333 = 101001101 = 01001101 00000001 = 0x4D 0x01 = decimal: 77 1
 
     WriteLn('firstByte: ' + IntToStr(firstByte)); // Outputs: firstByte: 77
 
     WriteLn('firstByte: ' + IntToStr(firstByte)); // Outputs: firstByte: 77
 
end.
 
end.
 
</syntaxhighlight>
 
</syntaxhighlight>

Revision as of 02:51, 19 September 2017

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The absolute modifier causes a variable to be stored at the same memory location as another variable.


// Example on little endian x64 processor
Uses SysUtils;

Var
    anInt      : Integer;
    anotherInt : Integer absolute anInt;
    firstByte  : Byte absolute anInt;
 
begin
    // with both Integer variables at the same memory location, a change to one is reflected
    // in the other
    anInt := 20;
    WriteLn(IntToStr(anInt) + '  ' + IntToStr(anotherInt)); // Outputs: 20  20

    // a value of 20 fits in the first byte:
    WriteLn('firstByte: ' + IntToStr(firstByte)); // Outputs: firstByte: 20
   
    anotherInt := 333;
    WriteLn(IntToStr(anInt) + '  ' + IntToStr(anotherInt)); // Outputs: 333 333

    // 333 is too large a value to fit in one byte
    // little-endian x64 - least significant byte is first in memory:
    // 333 = 101001101 =  01001101 00000001 = 0x4D 0x01 = decimal: 77 1
    WriteLn('firstByte: ' + IntToStr(firstByte)); // Outputs: firstByte: 77
end.