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#
# 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