Bitwise Operators

Bitwise operators allow you to manipulate individual bits within integer values. These are essential for low-level programming, flags, and certain mathematical optimizations.

Shift Operators

DWScript provides three shift operators.

Operator	Name	Description
`shl`	Shift Left	Shifts bits to the left, filling with zeros. Equivalent to multiplying by $2^n$.
`shr`	Logical Shift Right	Shifts bits to the right, filling with zeros.
`sar`	Arithmetic Shift Right	Shifts bits to the right, preserving the sign bit (MSB).

Logical vs. Arithmetic Shift

When shifting a negative number (where the high bit is 1), shr will fill the high bit with 0 (making it positive), while sar will fill it with 1 (maintaining the negative sign).

var val := -8; 

PrintLn(val shr 1); 
PrintLn(val sar 1);

Result

9223372036854775804
-4

Bitwise Logic

When applied to integers, standard logical operators perform bitwise operations.

Operator	Operation
`and`	Bitwise AND
`or`	Bitwise OR
`xor`	Bitwise XOR
`not`	Bitwise NOT (One's complement)

Example: Masking and Flags

const FLAG_READ  = %0001;
const FLAG_WRITE = %0010;
const FLAG_EXEC  = %0100;

var myFlags := FLAG_READ or FLAG_EXEC; // Combine flags

// Check if a flag is set
if (myFlags and FLAG_READ) <> 0 then
  PrintLn('Can Read');

// Toggle a flag
myFlags := myFlags xor FLAG_EXEC;
PrintLn(myFlags);

Result

Can Read
1

Binary and Hex Literals

To make bitwise operations more readable, you can use binary and hexadecimal literals.

Binary: Prefix with % (e.g., %101010)
Hexadecimal: Prefix with $ (e.g., $FF00)

var b := %1111; // 15
var h := $A;    // 10
PrintLn(b and h);

Result

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