Calcul très complexe d'heures !

Function TotHorM(r As Range)
   Application.Volatile
Dim a!, b!
Dim oCel As Range, x, i&, y, z, t!
   a = CSng(CDate("08:00"))
   b = CSng(CDate("12:00"))
   For Each oCel In r.Cells
      If oCel.Value <> "OFF" And Not IsEmpty(oCel) Then
         x = Split(Replace(Replace(Replace(Replace(Replace(oCel.Value, "H", ":", , , vbTextCompare), " - ", "#"), " -", "#"), "- ", "#"), "-", "#"))
         For i = 0 To UBound(x)
            y = Split(Trim(x(i)), "#")
            If y(0) = "24:00" Then y(0) = "00:00"
            If y(1) = "24:00" Then y(1) = "00:00"
            If CSng(CDate(y(1))) < CSng(CDate(y(0))) Then
               t = t + WorksheetFunction.Max(CSng(CDate(y(1))) - a, 0) + WorksheetFunction.Max(b - CSng(CDate(y(0))), 0)
            Else
               t = t + WorksheetFunction.Max(WorksheetFunction.Min(CSng(CDate(y(1))), b) - WorksheetFunction.Max(CSng(CDate(y(0))), a), 0)
            End If
         Next i
      End If
   Next oCel
   TotHorM = t
End Function
Function TotHorS(r As Range)
   Application.Volatile
Dim a!, b!
Dim oCel As Range, x, i&, y, z, t!
   a = CSng(CDate("12:30"))
   b = CSng(CDate("16:00"))
   For Each oCel In r.Cells
      If oCel.Value <> "OFF" And Not IsEmpty(oCel) Then
         x = Split(Replace(Replace(Replace(Replace(Replace(oCel.Value, "H", ":", , , vbTextCompare), " - ", "#"), " -", "#"), "- ", "#"), "-", "#"))
         For i = 0 To UBound(x)
            y = Split(Trim(x(i)), "#")
            If y(0) = "24:00" Then y(0) = "00:00"
            If y(1) = "24:00" Then y(1) = "00:00"
            If CSng(CDate(y(1))) < CSng(CDate(y(0))) Then
               t = t + WorksheetFunction.Max(CSng(CDate(y(1))) - a, 0) + WorksheetFunction.Max(b - CSng(CDate(y(0))), 0)
            Else
               t = t + WorksheetFunction.Max(WorksheetFunction.Min(CSng(CDate(y(1))), b) - WorksheetFunction.Max(CSng(CDate(y(0))), a), 0)
            End If
         Next i
      End If
   Next oCel
   TotHorS = t
End Function