vbscript 移位操作
在C和Java等编程语言中,可以方便地对变量进行移位运算,但是在VB中,却没有内置的移位运算符或者函数。
于是,我们得自己动手编写移位的运算函数。原理很简单,每向右移一位,就将被移位的变量的二进制除以2;每向左移一位,就将被移位的变量的二进制乘以2。于是可以写出以下函数:
以上写的两个左移和右移函数,非常简单,没有考虑机器字长以及传过来的变量类型等。
后来看到在VBS的MD5加密算法中,包含左移右移的函数,在这里,将它们单独拧出来,以作为左移右移函数的升级版本:
另外,在此基础上再添加两个位运算函数:循环左移和无符号数的加法运算。
来源:http://cdj850909.blog.163.com/blog/static/102457022009421101945908/
于是,我们得自己动手编写移位的运算函数。原理很简单,每向右移一位,就将被移位的变量的二进制除以2;每向左移一位,就将被移位的变量的二进制乘以2。于是可以写出以下函数:
+展开
' 按位左移
'
Public Function LShift(ByVal val, ByVal n)
LShift = val * 2 ^ n
End Function
'
' 按位右移
'
Public Function RShift(ByVal val, Byval n)
RShift = val \ (2 ^ n)
End Function
-VBScript
' 按位左移
'
Public Function LShift(ByVal val, ByVal n)
LShift = val * 2 ^ n
End Function
'
' 按位右移
'
Public Function RShift(ByVal val, Byval n)
RShift = val \ (2 ^ n)
End Function
以上写的两个左移和右移函数,非常简单,没有考虑机器字长以及传过来的变量类型等。
后来看到在VBS的MD5加密算法中,包含左移右移的函数,在这里,将它们单独拧出来,以作为左移右移函数的升级版本:
+展开
-VBScript
Private m_lOnBits(30)
Private m_l2Power(30)
Private Function Initialize()
m_lOnBits(0) = CLng(1)
m_lOnBits(1) = CLng(3)
m_lOnBits(2) = CLng(7)
m_lOnBits(3) = CLng(15)
m_lOnBits(4) = CLng(31)
m_lOnBits(5) = CLng(63)
m_lOnBits(6) = CLng(127)
m_lOnBits(7) = CLng(255)
m_lOnBits(8) = CLng(511)
m_lOnBits(9) = CLng(1023)
m_lOnBits(10) = CLng(2047)
m_lOnBits(11) = CLng(4095)
m_lOnBits(12) = CLng(8191)
m_lOnBits(13) = CLng(16383)
m_lOnBits(14) = CLng(32767)
m_lOnBits(15) = CLng(65535)
m_lOnBits(16) = CLng(131071)
m_lOnBits(17) = CLng(262143)
m_lOnBits(18) = CLng(524287)
m_lOnBits(19) = CLng(1048575)
m_lOnBits(20) = CLng(2097151)
m_lOnBits(21) = CLng(4194303)
m_lOnBits(22) = CLng(8388607)
m_lOnBits(23) = CLng(16777215)
m_lOnBits(24) = CLng(33554431)
m_lOnBits(25) = CLng(67108863)
m_lOnBits(26) = CLng(134217727)
m_lOnBits(27) = CLng(268435455)
m_lOnBits(28) = CLng(536870911)
m_lOnBits(29) = CLng(1073741823)
m_lOnBits(30) = CLng(2147483647)
m_l2Power(0) = CLng(1)
m_l2Power(1) = CLng(2)
m_l2Power(2) = CLng(4)
m_l2Power(3) = CLng(8)
m_l2Power(4) = CLng(16)
m_l2Power(5) = CLng(32)
m_l2Power(6) = CLng(64)
m_l2Power(7) = CLng(128)
m_l2Power(8) = CLng(256)
m_l2Power(9) = CLng(512)
m_l2Power(10) = CLng(1024)
m_l2Power(11) = CLng(2048)
m_l2Power(12) = CLng(4096)
m_l2Power(13) = CLng(8192)
m_l2Power(14) = CLng(16384)
m_l2Power(15) = CLng(32768)
m_l2Power(16) = CLng(65536)
m_l2Power(17) = CLng(131072)
m_l2Power(18) = CLng(262144)
m_l2Power(19) = CLng(524288)
m_l2Power(20) = CLng(1048576)
m_l2Power(21) = CLng(2097152)
m_l2Power(22) = CLng(4194304)
m_l2Power(23) = CLng(8388608)
m_l2Power(24) = CLng(16777216)
m_l2Power(25) = CLng(33554432)
m_l2Power(26) = CLng(67108864)
m_l2Power(27) = CLng(134217728)
m_l2Power(28) = CLng(268435456)
m_l2Power(29) = CLng(536870912)
m_l2Power(30) = CLng(1073741824)
End Function
Private Function LShift(lValue, iShiftBits)
If iShiftBits = 0 Then
LShift = lValue
Exit Function
ElseIf iShiftBits = 31 Then
If lValue And 1 Then
LShift = &H80000000
Else
LShift = 0
End If
Exit Function
ElseIf iShiftBits < 0 Or iShiftBits > 31 Then
Err.Raise 6
End If
If (lValue And m_l2Power(31 - iShiftBits)) Then
LShift = ((lValue And m_lOnBits(31 - (iShiftBits + 1))) * m_l2Power(iShiftBits)) Or &H80000000
Else
LShift = ((lValue And m_lOnBits(31 - iShiftBits)) * m_l2Power(iShiftBits))
End If
End Function
Private Function RShift(lValue, iShiftBits)
If iShiftBits = 0 Then
RShift = lValue
Exit Function
ElseIf iShiftBits = 31 Then
If lValue And &H80000000 Then
RShift = 1
Else
RShift = 0
End If
Exit Function
ElseIf iShiftBits < 0 Or iShiftBits > 31 Then
Err.Raise 6
End If
RShift = (lValue And &H7FFFFFFE) \ m_l2Power(iShiftBits)
If (lValue And &H80000000) Then
RShift = (RShift Or (&H40000000 \ m_l2Power(iShiftBits - 1)))
End If
End Function
Private m_l2Power(30)
Private Function Initialize()
m_lOnBits(0) = CLng(1)
m_lOnBits(1) = CLng(3)
m_lOnBits(2) = CLng(7)
m_lOnBits(3) = CLng(15)
m_lOnBits(4) = CLng(31)
m_lOnBits(5) = CLng(63)
m_lOnBits(6) = CLng(127)
m_lOnBits(7) = CLng(255)
m_lOnBits(8) = CLng(511)
m_lOnBits(9) = CLng(1023)
m_lOnBits(10) = CLng(2047)
m_lOnBits(11) = CLng(4095)
m_lOnBits(12) = CLng(8191)
m_lOnBits(13) = CLng(16383)
m_lOnBits(14) = CLng(32767)
m_lOnBits(15) = CLng(65535)
m_lOnBits(16) = CLng(131071)
m_lOnBits(17) = CLng(262143)
m_lOnBits(18) = CLng(524287)
m_lOnBits(19) = CLng(1048575)
m_lOnBits(20) = CLng(2097151)
m_lOnBits(21) = CLng(4194303)
m_lOnBits(22) = CLng(8388607)
m_lOnBits(23) = CLng(16777215)
m_lOnBits(24) = CLng(33554431)
m_lOnBits(25) = CLng(67108863)
m_lOnBits(26) = CLng(134217727)
m_lOnBits(27) = CLng(268435455)
m_lOnBits(28) = CLng(536870911)
m_lOnBits(29) = CLng(1073741823)
m_lOnBits(30) = CLng(2147483647)
m_l2Power(0) = CLng(1)
m_l2Power(1) = CLng(2)
m_l2Power(2) = CLng(4)
m_l2Power(3) = CLng(8)
m_l2Power(4) = CLng(16)
m_l2Power(5) = CLng(32)
m_l2Power(6) = CLng(64)
m_l2Power(7) = CLng(128)
m_l2Power(8) = CLng(256)
m_l2Power(9) = CLng(512)
m_l2Power(10) = CLng(1024)
m_l2Power(11) = CLng(2048)
m_l2Power(12) = CLng(4096)
m_l2Power(13) = CLng(8192)
m_l2Power(14) = CLng(16384)
m_l2Power(15) = CLng(32768)
m_l2Power(16) = CLng(65536)
m_l2Power(17) = CLng(131072)
m_l2Power(18) = CLng(262144)
m_l2Power(19) = CLng(524288)
m_l2Power(20) = CLng(1048576)
m_l2Power(21) = CLng(2097152)
m_l2Power(22) = CLng(4194304)
m_l2Power(23) = CLng(8388608)
m_l2Power(24) = CLng(16777216)
m_l2Power(25) = CLng(33554432)
m_l2Power(26) = CLng(67108864)
m_l2Power(27) = CLng(134217728)
m_l2Power(28) = CLng(268435456)
m_l2Power(29) = CLng(536870912)
m_l2Power(30) = CLng(1073741824)
End Function
Private Function LShift(lValue, iShiftBits)
If iShiftBits = 0 Then
LShift = lValue
Exit Function
ElseIf iShiftBits = 31 Then
If lValue And 1 Then
LShift = &H80000000
Else
LShift = 0
End If
Exit Function
ElseIf iShiftBits < 0 Or iShiftBits > 31 Then
Err.Raise 6
End If
If (lValue And m_l2Power(31 - iShiftBits)) Then
LShift = ((lValue And m_lOnBits(31 - (iShiftBits + 1))) * m_l2Power(iShiftBits)) Or &H80000000
Else
LShift = ((lValue And m_lOnBits(31 - iShiftBits)) * m_l2Power(iShiftBits))
End If
End Function
Private Function RShift(lValue, iShiftBits)
If iShiftBits = 0 Then
RShift = lValue
Exit Function
ElseIf iShiftBits = 31 Then
If lValue And &H80000000 Then
RShift = 1
Else
RShift = 0
End If
Exit Function
ElseIf iShiftBits < 0 Or iShiftBits > 31 Then
Err.Raise 6
End If
RShift = (lValue And &H7FFFFFFE) \ m_l2Power(iShiftBits)
If (lValue And &H80000000) Then
RShift = (RShift Or (&H40000000 \ m_l2Power(iShiftBits - 1)))
End If
End Function
另外,在此基础上再添加两个位运算函数:循环左移和无符号数的加法运算。
+展开
-VBScript
Private Function RotateLeft(lValue, iShiftBits)
RotateLeft = LShift(lValue, iShiftBits) Or RShift(lValue, (32 - iShiftBits))
End Function
Private Function AddUnsigned(lX, lY)
Dim lX4
Dim lY4
Dim lX8
Dim lY8
Dim lResult
lX8 = lX And &H80000000
lY8 = lY And &H80000000
lX4 = lX And &H40000000
lY4 = lY And &H40000000
lResult = (lX And &H3FFFFFFF) + (lY And &H3FFFFFFF)
If lX4 And lY4 Then
lResult = lResult Xor &H80000000 Xor lX8 Xor lY8
ElseIf lX4 Or lY4 Then
If lResult And &H40000000 Then
lResult = lResult Xor &HC0000000 Xor lX8 Xor lY8
Else
lResult = lResult Xor &H40000000 Xor lX8 Xor lY8
End If
Else
lResult = lResult Xor lX8 Xor lY8
End If
AddUnsigned = lResult
End Function
RotateLeft = LShift(lValue, iShiftBits) Or RShift(lValue, (32 - iShiftBits))
End Function
Private Function AddUnsigned(lX, lY)
Dim lX4
Dim lY4
Dim lX8
Dim lY8
Dim lResult
lX8 = lX And &H80000000
lY8 = lY And &H80000000
lX4 = lX And &H40000000
lY4 = lY And &H40000000
lResult = (lX And &H3FFFFFFF) + (lY And &H3FFFFFFF)
If lX4 And lY4 Then
lResult = lResult Xor &H80000000 Xor lX8 Xor lY8
ElseIf lX4 Or lY4 Then
If lResult And &H40000000 Then
lResult = lResult Xor &HC0000000 Xor lX8 Xor lY8
Else
lResult = lResult Xor &H40000000 Xor lX8 Xor lY8
End If
Else
lResult = lResult Xor lX8 Xor lY8
End If
AddUnsigned = lResult
End Function
来源:http://cdj850909.blog.163.com/blog/static/102457022009421101945908/
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