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/* libgcc routines for RL78
   Copyright (C) 2011
   Free Software Foundation, Inc.
   Contributed by Red Hat.

   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/>.  */

/* RL78 Trampoline support

  Since the RL78's RAM is not in the first 64k, we cannot "just" use a
  function pointer to point to a trampoline on the stack.  So, we
  create N fixed trampolines that read from an array, and allocate
  them as needed.

*/

r8      =       0xffef0
r10     =       0xffef2
r14     =       0xffef6

        .data
        .p2align        1
trampoline_array:

        .macro stub n

        .text
trampoline_\n:
        .type   trampoline_\n, @function
        movw    ax, !trampoline_chain_\n
        movw    r14, ax
        movw    ax, !trampoline_addr_\n
        br      ax
        .size   trampoline_\n, .-trampoline_\n

        .data
trampoline_frame_\n:
        .short  0
trampoline_stub_\n:
        .short  trampoline_\n
trampoline_chain_\n:
        .short  0
trampoline_addr_\n:
        .short  0

#define TO_FRAME 0
#define TO_STUB  2
#define TO_CHAIN 4
#define TO_ADDR  6
#define TO_SIZE  8

        .endm

        stub    0
        stub    1
        stub    2
        stub    3
        stub    4
        stub    5

trampoline_array_end:

/* Given the function pointer in R8 and the static chain
   pointer in R10, allocate a trampoline and return its address in
   R8. */

        .text
        .global ___trampoline_init
        .type   ___trampoline_init, @function
___trampoline_init:

        movw    hl, #trampoline_array
1:
        movw    ax, [hl + TO_ADDR]
        cmpw    ax, #0
        bz      $2f

        movw    ax, hl
        addw    ax, #TO_SIZE
        movw    hl, ax
        cmpw    ax, #trampoline_array_end
        bnz     $1b
        brk                     ; no more slots?

2:      movw    ax, r8
        movw    [hl + TO_ADDR], ax
        movw    ax, r10
        movw    [hl + TO_CHAIN], ax
        movw    ax, sp
        movw    [hl + TO_FRAME], ax

        movw    ax, [hl + TO_STUB]
        movw    r8, ax

        ret
        .size   ___trampoline_init, . - ___trampoline_init

        .global ___trampoline_uninit
        .type   ___trampoline_uninit, @function
___trampoline_uninit:
        movw    hl, #trampoline_array
        movw    ax, sp
        movw    bc, ax
1:
        movw    ax, [hl + TO_FRAME]
        cmpw    ax, bc
        bc      $2f

        clrw    ax
        movw    [hl + TO_ADDR], ax

2:
        movw    ax, hl
        addw    ax, #TO_SIZE
        movw    hl, ax
        cmpw    ax, #trampoline_array_end
        bnz     $1b

        ret
        .size   ___trampoline_uninit, . - ___trampoline_uninit