【干货】高精度计时，用于程序算法调试

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写程序的时候，尤其是算法类的，需要比对算法执行时间。这个代码集合了一些高手的经验

1. ' 大整数结构体
   
2. Private Type LARGE_INTEGER
   
3.     LowPart As Long
   
4.     HighPart As Long
   
5. End Type
   
6. 
   
7. ' 获取时间计数器计数值
   
8. Private Declare Function QueryPerformanceCounter Lib "kernel32" (lpPerformanceCount As LARGE_INTEGER) As Long
   
9. 
   
10. ' 获取震动频率：一个大整数
    
11. Private Declare Function QueryPerformanceFrequency Lib "kernel32" (lpFrequency As LARGE_INTEGER) As Long
    
12. 
    
13. ' 用于将大整数的字节复制到Currency类型，完成转换的工作
    
14. Private Declare Sub CopyMemory Lib "kernel32.dll" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)
    
15. 
    
16. ' 初始时间
    
17. Private initTime As LARGE_INTEGER
    
18. 
    
19. ' 每秒震动次数
    
20. Private freqCount As LARGE_INTEGER
    
21. 
    
22. ' 采样时振动器震动计数值
    
23. Private logTime As LARGE_INTEGER
    
24. 
    
25. ' 每秒震动次数的Currency类型数据
    
26. Private fFreq As Currency
    
27. 
    
28. ' 将一个长整型转换成高精度型数据
    
29. Private Function LargeIntToCurrency(liInput As LARGE_INTEGER) As Currency
    
30.     CopyMemory LargeIntToCurrency, liInput, LenB(liInput)
    
31.     LargeIntToCurrency = LargeIntToCurrency * 10000
    
32. End Function
    
33. 
    
34. ' 类初始化
    
35. Private Sub Class_Initialize()
    
36.     ' 获取振荡器的震荡频率
    
37.     If QueryPerformanceFrequency(freqCount) > 0 Then
    
38.         If QueryPerformanceCounter(initTime) > 0 Then
    
39.         Else
    
40.             Err.Raise 11, , "记录震荡次数出错！"
    
41.         End If
    
42.     Else
    
43.         Err.Raise 11, , "读取震荡频率出错！"
    
44.     End If
    
45.     fFreq = LargeIntToCurrency(freqCount)
    
46. End Sub
    
47. 
    
48. ' 重置计数器
    
49. Public Sub ReInit()
    
50.     Call Class_Initialize
    
51. End Sub
    
52. 
    
53. ' 重置计数器，并返回从上次重置计数器开始共流失的秒数。
    
54. Public Function ReInitGet() As Currency
    
55.     Dim cuStart As Currency
    
56.     Dim cuEnd As Currency
    
57.     QueryPerformanceCounter logTime
    
58.     cuStart = LargeIntToCurrency(initTime)
    
59.     cuEnd = LargeIntToCurrency(logTime)
    
60.     ReInitGet = (cuEnd - cuStart) / fFreq
    
61.     QueryPerformanceCounter initTime
    
62. End Function
    
63. 
    
64. ' 返回从上次重置计数器开始共流失的秒数，但不重置计数器
    
65. Public Function SmoothGet() As Currency
    
66.     Dim cuStart As Currency
    
67.     Dim cuEnd As Currency
    
68.     QueryPerformanceCounter logTime
    
69.     cuStart = LargeIntToCurrency(initTime)
    
70.     cuEnd = LargeIntToCurrency(logTime)
    
71.     SmoothGet = (cuEnd - cuStart) / fFreq
    
72. End Function

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