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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 "asm.h"
#include "regname.h"

.text

.global halt
.global memcpy
.global jump_to_kernel

halt:
    b halt

memcpy:
    srwi. r7, r5, 3
    addi r6, r3, -4
    addi r4, r4, -4
    beq 2f
    
    andi. r0, r6, 3
    mtctr r7
    bne 5f
    
    1:
    
    lwz r7, 4(r4)
    lwzu r8, 8(r4)
    stw r7, 4(r6)
    stwu r8, 8(r6)
    bdnz 1b
    
    andi. r5, r5, 7
    
    2:
    
    cmplwi 0, r5, 4
    blt 3f
    
    lwzu r0, 4(r4)
    addi r5, r5, -4
    stwu r0, 4(r6)
    
    3:
    
    cmpwi 0, r5, 0
    beqlr
    mtctr r5
    addi r4, r4, 3
    addi r6, r6, 3
    
    4:
    
    lbzu r0, 1(r4)
    stbu r0, 1(r6)
    bdnz 4b
    blr
    
    5:
    
    subfic r0, r0, 4
    mtctr r0
    
    6:
    
    lbz r7, 4(r4)
    addi r4, r4, 1
    stb r7, 4(r6)
    addi r6, r6, 1
    bdnz 6b
    subf r5, r0, r5
    rlwinm. r7, r5, 32-3, 3, 31
    beq 2b
    mtctr r7
    b 1b


jump_to_kernel:
    
    # r3 = bootinfo (pa)
    # r4 = bootinfo_size
    # r5 = trans (pa)
    # r6 = bytes to copy
    # r7 = real_mode (pa)
    
    # disable interrupts
    
    mfmsr r31
    rlwinm r31, r31, 0, 17, 15
    mtmsr r31
    
    # set real_mode meeting point address
    
    mtspr srr0, r7
    
    # jumps to real_mode
    
    mfmsr r31
    lis r30, ~0@h
    ori r30, r30, ~(msr_ir | msr_dr)@l
    and r31, r31, r30
    mtspr srr1, r31
    
    sync
    isync
    rfid

.section REALMODE, "ax"
.align PAGE_WIDTH
.global real_mode

real_mode:
    
    # copy kernel to proper location
    #
    # r5 = trans (pa)
    # r6 = bytes to copy
    
    li r31, PAGE_SIZE >> 2
    li r30, 0
    
    page_copy:
        
        cmpwi r6, 0
        beq copy_end
        
        # copy page
        
        mtctr r31
        lwz r29, 0(r5)
        
        copy_loop:
            
            lwz r28, 0(r29)
            stw r28, 0(r30)
            
            addi r29, r29, 4
            addi r30, r30, 4
            subi r6, r6, 4
            
            cmpwi r6, 0
            beq copy_end
            
            bdnz copy_loop
        
        addi r5, r5, 4
        b page_copy
    
    copy_end:
    
    # initially fill segment registers

    li r31, 16
    mtctr r31
    li r31, 0
    li r30, 0x2000

    seg_fill:
    
        mtsrin r30, r31
        addi r30, r30, 0x111
        addis r31, r31, 0x1000    # move to next SR
        
        bdnz seg_fill
    
    tlbia
    tlbsync
    
    # start the kernel
    #
    # r3 = bootinfo (pa)
    
    lis r31, KERNEL_START_ADDR@ha
    addi r31, r31, KERNEL_START_ADDR@l
    
    mtspr srr0, r31
    
    mfmsr r31
    ori r31, r31, (msr_ir | msr_dr)@l
    mtspr srr1, r31
    
    sync
    isync
    rfid

.align PAGE_WIDTH
.global trans
trans:
    .space (TRANS_SIZE * TRANS_ITEM_SIZE)