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楼主 |
发表于 2024-7-3 19:57:40
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本帖最后由 tlwh163 于 2024-7-3 19:59 编辑
有点草率 只能说对简单数据类型 勉强可以用 请指正!
Type FIFO_LONG
As Long Buff() '队列空间
As Long xSize '缓存容量
As Long iHead '数据首的下标
As Long Count '有效数据长度
End Type
Dim Fifo As FIFO_LONG
Sub FIFO_INIT(ByVal nSize As Long)
If nSize < 8 Then nSize = 8 '最小容量8
ReDim Fifo.Buff(0 To nSize + nSize - 1) '多1倍空间便于操作
Fifo.xSize = nSize : Fifo.iHead = 0 : Fifo.Count = 0
End Sub
'尾部压入数据(源数据地址,申请数量) 返回:实际装入数量
Function FIFO_PUSH(ByVal xPtr As Long, ByVal xCount As Long) As Long
If xPtr = 0 Or xCount <= 0 Or Fifo.Count = Fifo.xSize Then
FIFO_PUSH = 0 : Exit Function
End If
If (Fifo.Count + xCount) > Fifo.xSize Then '装不下了
xCount = (Fifo.xSize - Fifo.Count) '多的数据丢弃
End If
Dim k As Long : k = (Fifo.iHead + Fifo.Count)
If k >= Fifo.xSize Then k = k - Fifo.xSize '队列的插入点下标
memcpy Varptr(Fifo.Buff(k)), xPtr, xCount * LenB(Fifo.Buff(0))
Fifo.Count = Fifo.Count + xCount '修正队列计数器
FIFO_PUSH = xCount '返回实际接收多少个数据
k = k + xCount - Fifo.xSize
If k > 0 Then '队列空间外的数据(如果有),移动到队列下标0
k = k * LenB(Fifo.Buff(0))
memcpy Varptr(Fifo.Buff(0)), Varptr(Fifo.Buff(Fifo.xSize)), k
End If
End Function
''头部吐出数据(目标地址,请求数量) 返回:实际吐出数量
Function FIFO_SHIFT(ByVal xPtr As Long, ByVal xCount As Long) As Long
If xPtr = 0 Or xCount <= 0 Or Fifo.Count = 0 Then
FIFO_SHIFT = 0 : Exit Function
End If
If Fifo.Count < xCount Then xCount = Fifo.Count '能吐多少吐多少
Dim k As Long : k = Fifo.iHead + xCount
If k >= Fifo.xSize Then k = k - Fifo.xSize '新的队列首下标
If k > 0 Then '需要将队列头部的数据,搬一些到队列空间的尾部
memcpy Varptr(Fifo.Buff(Fifo.xSize)), Varptr(Fifo.Buff(0)), k * LenB(Fifo.Buff(0))
End If
memcpy xPtr, Varptr(Fifo.Buff(Fifo.iHead)), xCount * LenB(Fifo.Buff(0))
Fifo.Count = Fifo.Count - xCount '修正队列计数器
Fifo.iHead = k '修正队列首下标
FIFO_SHIFT = xCount '返回实际吐出多少个数据
End Function |
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