/* PowerPC support code for fibers and multithreading.
   Copyright (C) 2019-2020 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
<http://www.gnu.org/licenses/>.  */

#include "../common/threadasm.S"

/**
 * Performs a context switch.
 *
 * r3 - old context pointer
 * r4 - new context pointer
 *
 */
    .text
    .globl CSYM(_fiber_switchContext)
    .type CSYM(_fiber_switchContext), @function
    .align 2
CSYM(_fiber_switchContext):
    .cfi_startproc
    /* Save linkage area */
    mflr        0
    mfcr        5
    stw     0, 8(1)
    stw     5, 4(1)

    /* Save GPRs */
    stw     11, (-1 * 4)(1)
    stw     13, (-2 * 4)(1)
    stw     14, (-3 * 4)(1)
    stw     15, (-4 * 4)(1)
    stw     16, (-5 * 4)(1)
    stw     17, (-6 * 4)(1)
    stw     18, (-7 * 4)(1)
    stw     19, (-8 * 4)(1)
    stw     20, (-9 * 4)(1)
    stw     21, (-10 * 4)(1)
    stw     22, (-11 * 4)(1)
    stw     23, (-12 * 4)(1)
    stw     24, (-13 * 4)(1)
    stw     25, (-14 * 4)(1)
    stw     26, (-15 * 4)(1)
    stw     27, (-16 * 4)(1)
    stw     28, (-17 * 4)(1)
    stw     29, (-18 * 4)(1)
    stw     30, (-19 * 4)(1)
    stwu    31, (-20 * 4)(1)

    /* We update the stack pointer here, since we do not want the GC to
       scan the floating point registers. */

    /* Save FPRs */
    stfd    14, (-1 * 8)(1)
    stfd    15, (-2 * 8)(1)
    stfd    16, (-3 * 8)(1)
    stfd    17, (-4 * 8)(1)
    stfd    18, (-5 * 8)(1)
    stfd    19, (-6 * 8)(1)
    stfd    20, (-7 * 8)(1)
    stfd    21, (-8 * 8)(1)
    stfd    22, (-9 * 8)(1)
    stfd    23, (-10 * 8)(1)
    stfd    24, (-11 * 8)(1)
    stfd    25, (-12 * 8)(1)
    stfd    26, (-13 * 8)(1)
    stfd    27, (-14 * 8)(1)
    stfd    28, (-15 * 8)(1)
    stfd    29, (-16 * 8)(1)
    stfd    30, (-17 * 8)(1)
    stfd    31, (-18 * 8)(1)

    /* Update the old stack pointer */
    stw     1, 0(3)

    /* Set new stack pointer */
    addi        1, 4, 20 * 4

    /* Restore linkage area */
    lwz     0, 8(1)
    lwz     5, 4(1)

    /* Restore GPRs */
    lwz     11, (-1 * 4)(1)
    lwz     13, (-2 * 4)(1)
    lwz     14, (-3 * 4)(1)
    lwz     15, (-4 * 4)(1)
    lwz     16, (-5 * 4)(1)
    lwz     17, (-6 * 4)(1)
    lwz     18, (-7 * 4)(1)
    lwz     19, (-8 * 4)(1)
    lwz     20, (-9 * 4)(1)
    lwz     21, (-10 * 4)(1)
    lwz     22, (-11 * 4)(1)
    lwz     23, (-12 * 4)(1)
    lwz     24, (-13 * 4)(1)
    lwz     25, (-14 * 4)(1)
    lwz     26, (-15 * 4)(1)
    lwz     27, (-16 * 4)(1)
    lwz     28, (-17 * 4)(1)
    lwz     29, (-18 * 4)(1)
    lwz     30, (-19 * 4)(1)
    lwz     31, (-20 * 4)(1)

    /* Restore FPRs */
    lfd     14, (-1 * 8)(4)
    lfd     15, (-2 * 8)(4)
    lfd     16, (-3 * 8)(4)
    lfd     17, (-4 * 8)(4)
    lfd     18, (-5 * 8)(4)
    lfd     19, (-6 * 8)(4)
    lfd     20, (-7 * 8)(4)
    lfd     21, (-8 * 8)(4)
    lfd     22, (-9 * 8)(4)
    lfd     23, (-10 * 8)(4)
    lfd     24, (-11 * 8)(4)
    lfd     25, (-12 * 8)(4)
    lfd     26, (-13 * 8)(4)
    lfd     27, (-14 * 8)(4)
    lfd     28, (-15 * 8)(4)
    lfd     29, (-16 * 8)(4)
    lfd     30, (-17 * 8)(4)
    lfd     31, (-18 * 8)(4)

    /* Set condition and link register */
    mtcr        5
    mtlr        0

    /* Return and switch context */
    blr
    .cfi_endproc
    .size CSYM(_fiber_switchContext),.-CSYM(_fiber_switchContext)