sdcc/device/lib/ez80_z80/mulchar.s

   1 ;--------------------------------------------------------------------------
   2 ;  mulchar.s
   3 ;
   4 ;  Copyright (c) 2017-2021, Philipp Klaus Krause
   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 ; unsigned char x unsigned char multiplication is done by code generation.
  32
  33 .globl  __mulsuchar
  34 .globl  __muluschar
  35 .globl  __mulschar
  36
  37 ; operands have different sign
  38
  39 __muluschar:
  40         ld      e, l
  41         ld      d, #0
  42         ld      c, a
  43
  44         jr      signexte
  45
  46 __mulsuchar:
  47         ld      e, a
  48         ld      d, #0
  49         ld      c, l
  50
  51         jr      signexte
  52
  53 __mulschar:
  54         ld      e, a
  55         ld      c, l
  56
  57         ;; Need to sign extend before going in.
  58         rla
  59         sbc     a, a
  60         ld      d, a
  61 signexte:
  62         ld      a, c
  63         rla
  64         sbc     a, a
  65         ld      b, a
  66
  67         jp      __mul16
  68