--
-- file      : shiftOut.jal
-- author    : special [k]
-- date      : 28-JAN-2004
-- purpose   : Shift out data
-- pins      : Defined below
--
-- Copyright (C) 2004 special [k]
--
-- This library is free software; you can redistribute it and/or
-- modify it under the terms of the GNU Library General Public
-- License as published by the Free Software Foundation; either
-- version 2 of the License, or (at your option) any later version.
--
-- This library is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-- Library General Public License for more details.
-- 
-- You should have received a copy of the GNU Library General Public
-- License along with this library; if not, write to the
-- Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-- Boston, MA  02111-1307, USA.
--

-- --------------------------------------------------------------------------------
-- shiftOut(extOutClock, theOutMode, theOutData)
-- If extOutClock = low and theOutMode = high then shift out theData LSB first
-- If extOutClock = low and theOutMode = low then shift out theData MSB first
-- If extOutClock = high and theOutMode = high then shift out theData LSB first after clock pulse starts
-- If extOutClock = high and theOutMode = low then shift out theData MSB first after clock pulse starts
-- --------------------------------------------------------------------------------
-- How data is output:
--
--
-- ex. shiftOut(low, high, 155) -- 155 = 0b10011011
--
--     5V        ---     ---     ---     ---     ---     ---     ---     ---     
-- CLK          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   
--     0V ------     ---     ---     ---     ---     ---     ---     ---     ------
--     5V       -----   -----           -----   -----                   -----     
-- DATA        |     | |     |         |     | |     |                 |     |   
--     0V -----       -       ---------       -       -----------------       -----
--
--
-- ex. shiftOut(high, high, 155) -- 155 = 0b10011011
--
--     5V        ---     ---     ---     ---     ---     ---     ---     ---     
-- CLK          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   
--     0V ------     ---     ---     ---     ---     ---     ---     ---     ------
--     5V         --------------          --------------                  ---------
-- DATA          |              |        |              |                |    
--     0V -------                -------                 ----------------     
--
-- --------------------------------------------------------------------------------
procedure _shiftOutDelay is
--	delay_100mS(5)
end procedure

var volatile bit shiftOutClk is gp4
var volatile bit shiftOutClkDir is gp4_direction
var volatile bit shiftOutData is gp5
var volatile bit shiftOutDataDir is gp5_direction

procedure shiftOut( bit in extOutClock, bit in theOutMode, byte in theOutData ) is
	shiftOutData = low
	shiftOutDataDir = output

   	if extOutClock then
		shiftOutClk = low
		shiftOutClkDir = input
		if theOutMode then
			-- LSB first
			var bit dataBit at theOutData : 0
			for 8 loop
				while ! shiftOutClk loop
				end loop
				shiftOutData = dataBit
				theOutData = theOutData >> 1
				while shiftOutClk loop
				end loop
			end loop
		else
			-- MSB first
			var bit dataBit at theOutData : 7
			for 8 loop
				while ! shiftOutClk loop
				end loop
				shiftOutData = dataBit
				theOutData = theOutData << 1
				while shiftOutClk loop
				end loop
			end loop
		end if
	else
		shiftOutClk = low
		shiftOutClkDir = output
		if theOutMode then
			-- LSB first
			var bit dataBit at theOutData : 0
			for 8 loop
				shiftOutData = dataBit
				theOutData = theOutData >> 1
				shiftOutClk = high
				_shiftOutDelay 
				shiftOutClk = low
				_shiftOutDelay
			end loop
			shiftOutData = low
		else
			-- MSB first
			var bit dataBit at theOutData : 7
			for 8 loop
				shiftOutData = dataBit
				theOutData = theOutData << 1
				shiftOutClk = high
				_shiftOutDelay 
				shiftOutClk = low
				_shiftOutDelay 
			end loop
			shiftOutData = low
		end if
	end if
end procedure
-- --------------------------------------------------------------------------------