sdcc/device/lib/ds390/__sdcc_atomic_maybe_rollback.c

   1 /*-------------------------------------------------------------------------
   2 ;  __sdcc_atomic_maybe_rollback.c - C run-time: rollback for restartable
   3 ;  sequence implementation of C11 atomics
   4 ;
   5 ;  Copyright (c) 2024, Philipp Klaus Krause
   6 ;
   7 ;  This library is free software; you can redistribute it and/or modify it
   8 ;  under the terms of the GNU General Public License as published by the
   9 ;  Free Software Foundation; either version 2, or (at your option) any
  10 ;  later version.
  11 ;
  12 ;  This library is distributed in the hope that it will be useful,
  13 ;  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 ;  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  15 ;  GNU General Public License for more details.
  16 ;
  17 ;  You should have received a copy of the GNU General Public License
  18 ;  along with this library; see the file COPYING. If not, write to the
  19 ;  Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
  20 ;   MA 02110-1301, USA.
  21 ;
  22 ;  As a special exception, if you link this library with other files,
  23 ;  some of which are compiled with SDCC, to produce an executable,
  24 ;  this library does not by itself cause the resulting executable to
  25 ;  be covered by the GNU General Public License. This exception does
  26 ;  not however invalidate any other reasons why the executable file
  27 ;  might be covered by the GNU General Public License.
  28 ;------------------------------------------------------------------------*/
  29
  30 #ifdef __SDCC_MODEL_FLAT24
  31
  32 static void dummy(void) __naked
  33 {
  34         __asm
  35         .area HOME    (CODE)
  36
  37 ; This relies on the restartable implementations being aligned properly.
  38
  39 ___sdcc_atomic_maybe_rollback::
  40         push ar0
  41         mov  r0, SP
  42         dec  r0
  43         push psw
  44         cjne @r0, #(sdcc_atomic_exchange_rollback_start >> 16), 4$
  45         dec  r0
  46         cjne @r0, #(sdcc_atomic_exchange_rollback_start >> 8), 4$
  47         dec  r0
  48         cjne @r0, #<sdcc_atomic_exchange_rollback_start, 0$
  49 0$:
  50         jc   4$
  51         cjne @r0, #sdcc_atomic_exchange_rollback_end, 1$
  52 1$:
  53         jnc  4$
  54         ; we now know the interrupted routine was somewhere among the
  55         ; restartable implementations of atomic functions.
  56         push acc
  57         mov  a, @r0
  58         anl  a, #0x07
  59         cjne a, #6, 2$
  60 2$:
  61         jnc  3$
  62         ; we actually need to restart.
  63         mov  a, @r0
  64         anl  a, #0xf8
  65         mov  @r0, a
  66 3$:     ; inner skip
  67         pop acc
  68 4$:     ; outer skip
  69         pop psw
  70         pop ar0
  71         reti
  72
  73         __endasm;
  74 }
  75
  76 #endif
  77