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Report, edit, etc...Posted by Tarh on 2005-08-12 at 17:21:18

I know that Visual Basic has, and probably will always be, second to C++ when it comes to speed in bit calculations. Likewise, ASP (using VBScript) has, and probably will always be, second to PHP when it comes to speed in bit calculations. This functionalitiy, however, is needed for a project that I am working on. Since I am using ASP, optimization is also needed.

The basic idea was to create a function called CBit(), taking one ByVal parameter of type "byte" ("unsigned short int" in C++) (in theory - as VBScript uses all variants). The function would take that byte and output a string (char array) containing "1"s and "0"s in a series of bits. The value, of course, is returned by value.

I managed to whip up this little thing fairly quickly, but I'm sure that it could be made faster (don't get me wrong, it's very fast now - I just want to max it's speed).

CODE

Public Function CBit(number)
Dim exponent, buffer
exponent = 0
Do While (2 ^ exponent) * 2 - 1 < number
If exponent = 0 Then
exponent = exponent + 3
Else
exponent = exponent + 4
End If
Loop
Do
If 2 ^ exponent <= number Then
number = number - (2 ^ exponent)
buffer = buffer + "1"
Else
buffer = buffer + "0"
End If
If exponent > 0 Then
exponent = exponent - 1
Else
Exit Do
End If
Loop
CBit = buffer
End Function

Any suggestions . . . at all . . . would be greatly appreciated!

Report, edit, etc...Posted by ihatett_da_hated on 2005-08-12 at 18:21:51

Is this .NET?

Report, edit, etc...Posted by Tarh on 2005-08-12 at 18:25:25

Report, edit, etc...Posted by ihatett_da_hated on 2005-08-12 at 18:43:37

Does vbscript have bitwise operators (in C++: x | y)?

If so, use them.

Report, edit, etc...Posted by Tarh on 2005-08-12 at 20:01:56

The following bitwise logical operators are supported in VBScript:

SyntaxxxxxxxxxxxxxxxxxxxxxxxxxxDescription
arg1 And arg2xxxxxxxxxxxxxxxxxxBitwise AND
arg1 Or arg2xxxxxxxxxxxxxxxxxxxBitwise OR
arg1 Xor arg2xxxxxxxxxxxxxxxxxxBitwise XOR
Not arg1xxxxxxxxxxxxxxxxxxxxxxxBitwise Not
expr1 Eqv expr2xxxxxxxxxxxxxxxxBitwise equivalence
expr1 Imp expr2xxxxxxxxxxxxxxxxBitwise implication

ADDITION:
Just for the record - here's the revised code (much faster).

VB 6.0:

CODE

Private Function CBit$(number&)
Dim i&, buffer$
i& = 0
If number& = 0 Then _
CBit$ = "0": Exit Function
Do While (2& ^ i&) <= number&
If ((2& ^ i&) Xor number&) < number& Then
buffer$ = "1" & buffer$
Else
buffer$ = "0" & buffer$
End If
i& = i& + 1
Loop
CBit$ = buffer$
End Function

VBScript (All versions):

CODE

Function CBit(number)
Dim i, buffer
i = 0
If number = 0 Then
CBit = "0"
Exit Function
End If
Do While (2 ^ i) <= number
If ((2 ^ i) Xor number) < number Then
buffer = "1" + buffer
Else
buffer = "0" + buffer
End If
i = i + 1
Loop
CBit = buffer
End Function

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