sdcc/device/lib/r800/__sdcc_critical.s

   1 ;--------------------------------------------------------------------------
   2 ;  __sdcc_critical.s
   3 ;
   4 ;  Copyright (C) 2020, Sergey Belyashov
   5 ;
   6 ;  This library is free software; you can redistribute it and/or modify it
   7 ;  under the terms of the GNU General Public License as published by the
   8 ;  Free Software Foundation; either version 2, or (at your option) any
   9 ;  later version.
  10 ;
  11 ;  This library is distributed in the hope that it will be useful,
  12 ;  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 ;  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14 ;  GNU General Public License for more details.
  15 ;
  16 ;  You should have received a copy of the GNU General Public License
  17 ;  along with this library; see the file COPYING. If not, write to the
  18 ;  Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
  19 ;   MA 02110-1301, USA.
  20 ;
  21 ;  As a special exception, if you link this library with other files,
  22 ;  some of which are compiled with SDCC, to produce an executable,
  23 ;  this library does not by itself cause the resulting executable to
  24 ;  be covered by the GNU General Public License. This exception does
  25 ;  not however invalidate any other reasons why the executable file
  26 ;   might be covered by the GNU General Public License.
  27 ;--------------------------------------------------------------------------
  28
  29         .area   _CODE
  30
  31         .globl ___sdcc_critical_enter
  32 ;
  33 ; NMOS Z80 compatible
  34 ; this function cannot be placed at 0x0000...0x00ff addresses
  35 ;
  36 ___sdcc_critical_enter::
  37         xor     a, a
  38         push    af
  39         pop     af
  40         ld      a, i
  41         di
  42         ret     pe      ;enabled interrupts
  43         dec     sp
  44         dec     sp
  45         pop     af
  46         or      a, a    ;A = 0 if interrupts disabled
  47         jr      NZ, 00100$
  48 ;interrupts disabled
  49         sub     a, a    ;force P/V = 0
  50         ret
  51 ;interrupts enabled
  52 00100$:
  53         xor     a, a    ;force P/V = 1
  54         ret