Michael Fabian Dirks
139 lines
4.0 KiB
BlitzBasic
139 lines
4.0 KiB
BlitzBasic
; ---------------------------------------------------------------------------- ;
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; Example 4 - Calling Functions (Advanced)
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; ---------------------------------------------------------------------------- ;
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; License: Creative Commons Attribution 2.0
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; Author: Michael Fabian Dirks<michael.dirks@realitybends.de>
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; Prerequisite: Example 3
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; We now know how to use return values correctly and thus have knowledge about
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; the first 4 of 1364 functions to call a pointer.
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; Now you know about 4 different ways of calling a Function, what about the
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; other 1360 that are left? Those are combinations of return types, parameter
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; count and parameter types.
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; BlitzPointer supports functions with up to four parameters, given that all
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; parameters have a supported type.
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; There are three parameter types in Blitz that we can use:
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; ---------------------------------------------------------------------------- ;
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; Type Id Description Calling Function
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; ---------------------------------------------------------------------------- ;
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; int I 32-bit Integer BlitzPointer_CallFunction*I
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; float F Floating Point BlitzPointer_CallFunction*F
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; type I Type Object BlitzPointer_CallFunction*I
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; pointer P Memory Pointer BlitzPointer_CallFunction*P
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;
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; We can't pass strings as parameters, but we can pass types as parameters,
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; which allows us to pass strings in a type.
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Include "Example_Shared.bb"
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ExampleInit()
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; Example Function: Divide p1 by 60 and return the result.
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Global fpCurInGameSecond = 0
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Function CurInGameSecond%(p1%=0)
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If fpCurInGameSecond = 0 Then
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fpCurInGameSecond = BlitzPointer_GetFunctionPointer()
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Return
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EndIf
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Text 5, 15, "IIFunction"
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Text 125, 15, p1
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Return (p1 Shr 2) / 15 ; Division by 60
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End Function
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CurInGameSecond()
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; Example Function: Multiply p1 by p2 and return the result.
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Global fpCurInGameSecondEx = 0
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Function CurInGameSecondEx#(p1%=0, p2#=0)
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If fpCurInGameSecondEx = 0 Then
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fpCurInGameSecondEx = BlitzPointer_GetFunctionPointer()
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Return
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EndIf
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Text 5, 30, "FIFFunction"
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Text 125, 30, p1
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Text 245, 30, p2
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Return p1 * p2
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End Function
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CurInGameSecondEx()
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; Example Function: Work around the fact that Strings can't be passed.
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Type MyType
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Field Name$
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Field Desc$
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End Type
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Local MT.MyType = New MyType
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MT\Name = "Hello"
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MT\Desc = "World"
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Global fpDisplayMyType = 0
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Function DisplayMyType(p1.MyType)
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If fpDisplayMyType = 0 Then
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fpDisplayMyType = BlitzPointer_GetFunctionPointer()
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Return
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EndIf
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Text 5, 45, "VTFunction"
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Text 125, 45, Hex(Int(p1))
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If p1 <> Null Then
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Text 245, 45, p1\Name
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Text 365, 45, p1\Desc
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EndIf
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End Function
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DisplayMyType(Null)
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; Example Function: Convert between Float and Int easily
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; For this to work we must take and return a float.
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Global fpConvertIntFloat
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Function ConvertIntFloat#(p1#=0)
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If fpConvertIntFloat = 0 Then
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fpConvertIntFloat = BlitzPointer_GetFunctionPointer()
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Return
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EndIf
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Return p1
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End Function
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ConvertIntFloat()
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; Pointer-parameters are a bit trickier and require memory access, see UserLibs.txt.
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Local Frame% = 0
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While Not KeyHit(1)
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ExampleUpdate()
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Text 0, 0, "Functions"
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Text 120, 0, "Parameter 1"
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Text 240, 0, "Parameter 2"
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Text 360, 0, "Parameter 3"
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Text 480, 0, "Parameter 4"
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Text 600, 0, "Result"
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Text 605, 15, BlitzPointer_CallFunctionII(fpCurInGameSecond, Frame)
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Text 605, 30, BlitzPointer_CallFunctionFIF(fpCurInGameSecondEx, Frame, 0.016666666)
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; In order to pass a Type-object to a function, we need to get a pointer for it.
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; Thankfully, Blitz can do this natively by calling Int() on it.
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BlitzPointer_CallFunctionVI fpDisplayMyType, Int(MT)
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Local TempFlt# = Frame / 60.0
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Local TempInt% = BlitzPointer_CallFunctionIF(fpConvertIntFloat, TempFlt)
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Text 5, 60, "Float -> Int"
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Text 125, 60, TempFlt
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Text 605, 60, Hex(TempInt)
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Text 5, 75, "Int -> Float"
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Text 125, 75, Hex(TempInt)
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Text 605, 75, BlitzPointer_CallFunctionFI(fpConvertIntFloat, TempInt)
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ExampleLoop()
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; Allow us to pause execution
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While KeyDown(57)
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WaitTimer(Example_Timer)
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Wend
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Frame=Frame+1
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Wend
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End
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;~IDEal Editor Parameters:
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;~C#Blitz3D |