/*
 * This file is part of the COMROGUE Operating System for Raspberry Pi
 *
 * Copyright (c) 2013, Eric J. Bowersox / Erbosoft Enterprises
 * All rights reserved.
 *
 * This program is free for commercial and non-commercial use as long as the following conditions are
 * adhered to.
 *
 * Copyright in this file remains Eric J. Bowersox and/or Erbosoft, and as such any copyright notices
 * in the code are not to be removed.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
 * 
 * * Redistributions of source code must retain the above copyright notice, this list of conditions and
 *   the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and
 *   the following disclaimer in the documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * "Raspberry Pi" is a trademark of the Raspberry Pi Foundation.
 */
.section ".text"

/*------------------------
 * Low-level IO functions
 *------------------------
 */

/*
 * Writes a 32-bit word of data to a memory-mapped IO port.
 *
 * Parameters:
 *   - kaPort = Kernel address of the IO port to write to.
 *   - uiData = Data to be written.
 *
 * Returns:
 * Nothing.
 *
 * Side effects:
 * Writing to any given IO port may have arbitrary side effects.
 */
.globl llIOWriteK
llIOWriteK:
	str r1,[r0]
	bx lr

/*
 * Reads a 32-bit word of data from a memory-mapped IO port.
 *
 * Parameters:
 *   - kaPort = Kernel address of the IO port we read from.
 *
 * Returns:
 * The word of data read from the IO port.
 *
 * Side effects:
 * Reading from any given IO port may have arbitrary side effects.
 */
.globl llIOReadK
llIOReadK:
	ldr r0,[r0]
	bx lr

/*
 * Delays for a certain number of cycles, to allow an IO operation to work.
 *
 * Parameters:
 *   - uiTicks = The number of "ticks" to delay.
 *
 * Returns:
 * Nothing.
 */
.globl llIODelay
llIODelay:
	push {lr}
.delaytop:
	nop
	nop
	bl .delayreturn
	nop
	nop
	subs r0, r0, #1
	bne .delaytop
	pop {lr}
.delayreturn:
	bx lr