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#
# Copyright (C) 2005 Jakub Jermar
# 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.
#

.text

.global context_save
.global context_restore

context_save:
    alloc loc0 = ar.pfs, 1, 8, 0, 0
    mov loc1 = ar.unat  ;;
    /* loc2 */
    mov loc3 = ar.rsc

    .auto

    /*
     * Flush dirty registers to backing store.
     * After this ar.bsp and ar.bspstore are equal.
     */
    flushrs
    mov loc4 = ar.bsp   
    
    /*
     * Put RSE to enforced lazy mode.
     * So that ar.rnat can be read.
     */
    and loc5 = ~3, loc3
    mov ar.rsc = loc5
    mov loc5 = ar.rnat

    .explicit

    mov loc6 = ar.lc
    
    /*
     * Save application registers
     */
    st8 [in0] = loc0, 8 ;;  /* save ar.pfs */
    st8 [in0] = loc1, 8 ;;  /* save ar.unat (caller) */
    mov loc2 = in0      ;;
    add in0 = 8, in0    ;;  /* skip ar.unat (callee) */
    st8 [in0] = loc3, 8 ;;  /* save ar.rsc */
    st8 [in0] = loc4, 8 ;;  /* save ar.bsp */
    st8 [in0] = loc5, 8 ;;  /* save ar.rnat */
    st8 [in0] = loc6, 8 ;;  /* save ar.lc */
    
    /*
     * Save general registers including NaT bits
     */
    st8.spill [in0] = r1, 8     ;;
    st8.spill [in0] = r4, 8     ;;
    st8.spill [in0] = r5, 8     ;;
    st8.spill [in0] = r6, 8     ;;
    st8.spill [in0] = r7, 8     ;;
    st8.spill [in0] = r12, 8    ;;  /* save sp */
    st8.spill [in0] = r13, 8    ;;  /* save tp */

    mov loc3 = ar.unat      ;;
    st8 [loc2] = loc3       /* save ar.unat (callee) */

    /*
     * Save branch registers
     */
    mov loc2 = b0       ;;
    st8 [in0] = loc2, 8     /* save pc */
    mov loc3 = b1       ;;
    st8 [in0] = loc3, 8
    mov loc4 = b2       ;;
    st8 [in0] = loc4, 8
    mov loc5 = b3       ;;
    st8 [in0] = loc5, 8
    mov loc6 = b4       ;;
    st8 [in0] = loc6, 8
    mov loc7 = b5       ;;
    st8 [in0] = loc7, 8

    /*
     * Save predicate registers
     */
    mov loc2 = pr       ;;
    st8 [in0] = loc2, 8 ;;
    
    mov ar.unat = loc1
    
    add r8 = r0, r0, 1      /* context_save returns 1 */
    br.ret.sptk.many b0

context_restore:
    alloc loc0 = ar.pfs, 1, 9, 0, 0 ;;

    ld8 loc0 = [in0], 8 ;;  /* load ar.pfs */
    ld8 loc1 = [in0], 8 ;;  /* load ar.unat (caller) */
    ld8 loc2 = [in0], 8 ;;  /* load ar.unat (callee) */
    ld8 loc3 = [in0], 8 ;;  /* load ar.rsc */
    ld8 loc4 = [in0], 8 ;;  /* load ar.bsp */
    ld8 loc5 = [in0], 8 ;;  /* load ar.rnat */
    ld8 loc6 = [in0], 8 ;;  /* load ar.lc */
    
    .auto   

    /*
     * Invalidate the ALAT
     */
    invala

    /*
     * Put RSE to enforced lazy mode.
     * So that ar.bspstore and ar.rnat can be written.
     */
    movl loc8 = ~3
    and loc8 = loc3, loc8
    mov ar.rsc = loc8

    /*
     * Flush dirty registers to backing store.
     * We do this because we want the following move
     * to ar.bspstore to assign the same value to ar.bsp.
     */
    flushrs

    /*
     * Restore application registers
     */
    mov ar.bspstore = loc4  /* rse.bspload = ar.bsp = ar.bspstore = loc4 */
    mov ar.rnat = loc5
    mov ar.pfs = loc0
    mov ar.rsc = loc3

    .explicit

    mov ar.unat = loc2  ;;
    mov ar.lc = loc6
    
    /*
     * Restore general registers including NaT bits
     */
    ld8.fill r1 = [in0], 8  ;;
    ld8.fill r4 = [in0], 8  ;;
    ld8.fill r5 = [in0], 8  ;;
    ld8.fill r6 = [in0], 8  ;;
    ld8.fill r7 = [in0], 8  ;;
    ld8.fill r12 = [in0], 8 ;;  /* restore sp */
    ld8.fill r13 = [in0], 8 ;;

    /* 
     * Restore branch registers
     */
    ld8 loc2 = [in0], 8 ;;  /* restore pc */
    mov b0 = loc2
    ld8 loc3 = [in0], 8 ;;
    mov b1 = loc3
    ld8 loc4 = [in0], 8 ;;
    mov b2 = loc4
    ld8 loc5 = [in0], 8 ;;
    mov b3 = loc5
    ld8 loc6 = [in0], 8 ;;
    mov b4 = loc6
    ld8 loc7 = [in0], 8 ;;
    mov b5 = loc7

    /*
     * Restore predicate registers
     */
    ld8 loc2 = [in0], 8 ;;
    mov pr = loc2, ~0
    
    mov ar.unat = loc1
    
    mov r8 = r0         /* context_restore returns 0 */
    br.ret.sptk.many b0