libgcc/config/rl78/trampoline.S

   1 /* libgcc routines for RL78
   2    Copyright (C) 2011-2019 Free Software Foundation, Inc.
   3    Contributed by Red Hat.
   4
   5    This file is part of GCC.
   6
   7    GCC is free software; you can redistribute it and/or modify it
   8    under the terms of the GNU General Public License as published
   9    by the Free Software Foundation; either version 3, or (at your
  10    option) any later version.
  11
  12    GCC is distributed in the hope that it will be useful, but WITHOUT
  13    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  15    License for more details.
  16
  17    Under Section 7 of GPL version 3, you are granted additional
  18    permissions described in the GCC Runtime Library Exception, version
  19    3.1, as published by the Free Software Foundation.
  20
  21    You should have received a copy of the GNU General Public License and
  22    a copy of the GCC Runtime Library Exception along with this program;
  23    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24    <http://www.gnu.org/licenses/>.  */
  25
  26 /* RL78 Trampoline support
  27
  28   Since the RL78's RAM is not in the first 64k, we cannot "just" use a
  29   function pointer to point to a trampoline on the stack.  So, we
  30   create N fixed trampolines that read from an array, and allocate
  31   them as needed.
  32
  33 */
  34
  35 #include "vregs.h"
  36
  37         .data
  38         .p2align        1
  39 trampoline_array:
  40
  41         .macro stub n
  42
  43         .text
  44 trampoline_\n:
  45         .type   trampoline_\n, @function
  46         movw    ax, !trampoline_chain_\n
  47         movw    r14, ax
  48         movw    ax, !trampoline_addr_\n
  49         br      ax
  50         .size   trampoline_\n, .-trampoline_\n
  51
  52         .data
  53 trampoline_frame_\n:
  54         .short  0
  55 trampoline_stub_\n:
  56         .short  trampoline_\n
  57 trampoline_chain_\n:
  58         .short  0
  59 trampoline_addr_\n:
  60         .short  0
  61
  62 #define TO_FRAME 0
  63 #define TO_STUB  2
  64 #define TO_CHAIN 4
  65 #define TO_ADDR  6
  66 #define TO_SIZE  8
  67
  68         .endm
  69
  70         stub    0
  71         stub    1
  72         stub    2
  73         stub    3
  74         stub    4
  75         stub    5
  76
  77 trampoline_array_end:
  78
  79 /* Given the function pointer in R8 and the static chain
  80    pointer in R10, allocate a trampoline and return its address in
  81    R8. */
  82
  83 START_FUNC ___trampoline_init
  84         movw    hl, #trampoline_array
  85
  86 1:      movw    ax, [hl + TO_ADDR]
  87         cmpw    ax, #0
  88         bz      $2f
  89
  90         movw    ax, hl
  91         addw    ax, #TO_SIZE
  92         movw    hl, ax
  93         cmpw    ax, #trampoline_array_end
  94         bnz     $1b
  95         brk                     ; no more slots?
  96
  97 2:      movw    ax, r8
  98         movw    [hl + TO_ADDR], ax
  99         movw    ax, r10
 100         movw    [hl + TO_CHAIN], ax
 101         movw    ax, sp
 102         movw    [hl + TO_FRAME], ax
 103
 104         movw    ax, [hl + TO_STUB]
 105         movw    r8, ax
 106         ret
 107 END_FUNC ___trampoline_init
 108
 109
 110 START_FUNC ___trampoline_uninit
 111         movw    hl, #trampoline_array
 112         movw    ax, sp
 113         movw    bc, ax
 114
 115 1:      movw    ax, [hl + TO_FRAME]
 116         cmpw    ax, bc
 117         bc      $2f
 118
 119         clrw    ax
 120         movw    [hl + TO_ADDR], ax
 121
 122 2:      movw    ax, hl
 123         addw    ax, #TO_SIZE
 124         movw    hl, ax
 125         cmpw    ax, #trampoline_array_end
 126         bnz     $1b
 127
 128         ret
 129 END_FUNC ___trampoline_uninit