'----------------------------------------------------------------------
'
'' Module: PinFunc.bas
'
' Copyright 2005 Elba Corp.
' All rights reserved.
'
' Non-exclusive permission to use, copy, modify, and distribute this
' software for any purpose and without fee is hereby granted, provided:
'   1) that the above copyright notice is retained in the source code and,
'   2) that it is understood and agreed that no warranty of any kind,
'      express or implied is provided.
' Use of this code in any manner shall be prima facie evidence of
' acceptance of these terms.
'
' You may contact the author by email at dkinzer@zbasic.net.
'
'-------------------------------------------------------------------------------

' Overview
' This module provides some routines for manipulating I/O pins for
' the ZX-24.  The code could be adapted to other ZX microcontrollers.

'-------------------------------------------------------------------------------

' This table, indexed by (pinNumber - 24) gives the PortB bit
' corresponding to pins 25-27.
Private pinTbl as ByteVectorData({ 7, 5, 4 })

'----------------------------------------------------------------------
'
'' PinState
'
' Determine the current state of a ZX-24 output pin.  If an invalid pin number
' is passed, zero is returned.  If the pin number of an input is passed,
' the result is meaningless.
'
Function PinState(ByVal pin as Byte) as Byte
	Select Case pin
	Case 5 To 12
		PinState = GetBit(Register.PortC, 12 - pin)
	Case 13 To 20
		PinState = GetBit(Register.PortA, 20 - pin)
	Case 25 To 27
		PinState = GetBit(Register.PortB, pinTbl(pin - 24))
	Case Else
		PinState = 0
	End Select
End Function

'----------------------------------------------------------------------
'
'' TogglePin
'
' Given a ZX-24 pin number, if it is an output, the output state is
' set to the opposite state.  If the an invalid pin or an input pin is
' passed, no action is taken.
'
Sub TogglePin(ByVal pin as Byte)
	If (PinIsOutput(pin) <> 0) Then
		Call PutPin(pin, PinState(pin) Xor 1)
	End If
End Sub

'----------------------------------------------------------------------
'
'' PinIsOutput
'
' Determine if a given ZX-24 pin is an output.  If a valid pin is passed
' and that pin is an output, 1 is returned otherwise zero is returned.
'
Function PinIsOutput(ByVal pin as Byte) as Byte
	Select Case pin
	Case 5 To 12
		PinIsOutput = GetBit(Register.DDRC, 12 - pin)
	Case 13 To 20
		PinIsOutput = GetBit(Register.DDRA, 20 - pin)
	Case 25 To 27
		PinIsOutput = GetBit(Register.DDRB, pinTbl(pin - 24))
	Case Else
		PinIsOutput = 0
	End Select
End Function