| Code |
| MakeDWord01 |
Public Function MakeDWord01(LoWord As Integer, HiWord As Integer) As Long
' by Donald, donald@xbeat.net, 20001205
MakeDWord01 = (HiWord * &H10000) + (LoWord And &HFFFF&)
End Function
|
| MakeDWord02 |
Public Function MakeDWord02(LoWord As Integer, HiWord As Integer) As Long
' by Donald, donald@xbeat.net, 20001205
MakeDWord02 = (HiWord * &H10000) Or (LoWord And &HFFFF&)
End Function
|
| MakeDWord03 |
Public Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _
(pDst As Any, pSrc As Any, ByVal ByteLen As Long)
Public Function MakeDWord03(LoWord As Integer, HiWord As Integer) As Long
' by Donald, donald@xbeat.net, 20001205
CopyMemory MakeDWord03, LoWord, 2&
CopyMemory ByVal VarPtr(MakeDWord03) + 2&, HiWord, 2&
End Function
|
| MakeDWord04 |
Private Type T1Long
lDWord As Long
End Type
Private Type T2Int
iLoWord As Integer
iHiWord As Integer
End Type
Public Function MakeDWord04(LoWord As Integer, HiWord As Integer) As Long
' by Donald, donald@xbeat.net, 20001205
Dim u2Int As T2Int
Dim u1Long As T1Long
u2Int.iLoWord = LoWord
u2Int.iHiWord = HiWord
LSet u1Long = u2Int
MakeDWord04 = u1Long.lDWord
End Function
|
| MakeDWord05 |
Public Function MakeDWord05(ByVal LoWord As Integer, ByVal HiWord As Integer) As Long
' by G.Beckmann, G.Beckmann@NikoCity.de, 20001207
MakeDWord05 = (HiWord * &H10000) Or (LoWord And &HFFFF&)
End Function
|
| MakeDWord06 |
Public Function MakeDWord06(ByVal LoWord As Integer, ByVal HiWord As Integer) As Long
' by Karl E. Peterson, http://www.mvps.org/vb, 20001207
' High word is coerced to Long to allow it to
' overflow limits of multiplication which shifts
' it left.
MakeDWord06 = (CLng(HiWord) * &H10000) Or (LoWord And &HFFFF&)
End Function
|
| Calls |
|
1 | lRet = MakeDWord(1, 1)
|
|
2 | lRet = MakeDWord(-1, -1)
|
| Charts |
|
| Conclusions |
- Note, that the only difference between MakeDWord01 and MakeDWord02 is the use of "Or" instead of "+" in the latter, which gives it a considerable boost.
- Passing the arguments ByVal (MakeDWord05/06) looks better than ByRef (MakeDWord02).
Note, however, that this is only true if the passed variables or constants have procedure scope; when you pass global scope arguments, ByRef is better.
- Regarding the differences between MakeDWord05 and MakeDWord06: do not take those numbers too serious. Functions that take about 30 nanoseconds per call are real fast, actually so fast that normally hidden conditions and processes become visible in the timing results. In other words, our measurements are distorted by a type of noise that is inherent to the execution of computer programs (and *not* just the normal background-hum of a multitasking OS), and probably (even more tragic!) also inherent to the measurement of execution speed itself. There is a way out of this dilemma, but it's not VB anymore:
At these speed levels, performance measurement is best (if not only) done by disassembling the executable and counting assembly instructions.
- As could be expected, there are no significant differences between the two calls. A byte is a byte.
- The API-doping of MakeDWord03 proves to be high-class Valium.
- Using UDTs and LSet (MakeDWord04) is an idea with no future.
|
 Got comments? |
 |
|
