#
# Copyright (c) 2006 Martin Decky
# All rights reserved.
#
# 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.
# - The name of the author may not be used to endorse or promote products
#   derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
#

#include "regname.h"

.set noat
.set noreorder
.set nomacro

.text

.global halt
.global memcpy
.global jump_to_kernel

halt:
	b halt
	nop
	
memcpy:
	addiu	$v0,$a1,3
	li	$v1,-4			# 0xfffffffffffffffc
	and	$v0,$v0,$v1
	beq	$a1,$v0,3f
	move	$t0,$a0
	move	$t2,$a0			# save dst

0:
	beq	$a2,$zero,2f
	move	$a3,$zero

1:
	addu	$v0,$a1,$a3
	lbu	$a0,0($v0)
	addu	$v1,$t0,$a3
	addiu	$a3,$a3,1
	bne	$a3,$a2,1b
	sb	$a0,0($v1)

2:
	jr	$ra
	move	$v0,$t2

3:
	addiu	$v0,$a0,3
	and	$v0,$v0,$v1
	bne	$a0,$v0,0b
	srl	$t1,$a2,2

	beq	$t1,$zero,5f
	move	$a3,$zero

	move	$a3,$zero
	move	$a0,$zero
4:
	addu	$v0,$a1,$a0
	lw	$v1,0($v0)
	addiu	$a3,$a3,1
	addu	$v0,$t0,$a0
	sw	$v1,0($v0)
	bne	$a3,$t1,4b
	addiu	$a0,$a0,4

5:
	andi	$a2,$a2,0x3
	beq	$a2,$zero,2b
	nop

	sll	$v0,$a3,2
	addu	$t1,$v0,$t0
	move	$a3,$zero
	addu	$t0,$v0,$a1
6:
	addu	$v0,$t0,$a3
	lbu	$a0,0($v0)
	addu	$v1,$t1,$a3
	addiu	$a3,$a3,1
	bne	$a3,$a2,6b
	sb	$a0,0($v1)

	jr	$ra
	move	$v0,$t2

jump_to_kernel:
	#
	# TODO
	# Make sure that the I-cache, D-cache and memory are mutually coherent
	# before passing control to the copied code.
	#
	j $a0
	nop