src/Stack.cpp

   1 /*
   2  *      avr-sim: An atmel AVR simulator
   3  *  Copyright (C) 2008  Tom Haber
   4  *
   5  *  This program is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation, either version 3 of the License, or
   8  *  (at your option) any later version.
   9
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include "Stack.h"
  20 #include "Registers.h"
  21 #include <cstring>
  22
  23 namespace avr {
  24
  25         Stack::Stack(Bus & bus, MMU & mmu, word mask)
  26                 : Hardware(bus), mmu(mmu), mask(mask), sp(0) {
  27         }
  28
  29         void Stack::push(unsigned char val) {
  30                 mmu.writeByte(sp, val);
  31                 sp--;
  32                 setSP( sp );
  33         }
  34
  35         unsigned char Stack::pop() {
  36                 sp++;
  37                 setSP( sp );
  38
  39                 return mmu.readByte(sp);
  40         }
  41
  42         void Stack::setSP(word sp) {
  43                 sp &= mask;
  44                 spl->set( getSPL() );
  45                 sph->set( getSPH() );
  46                 this->sp = sp;
  47         }
  48
  49         bool Stack::attachReg(const char *name, IORegister *reg) {
  50                 if( strcmp(name, "sph") == 0 )
  51                         sph = reg;
  52                 else if( strcmp(name, "spl") == 0 )
  53                         spl = reg;
  54                 else
  55                         return false;
  56
  57                 reg->registerHW(this);
  58                 return true;
  59         }
  60
  61         bool Stack::finishBuild() {
  62                 return ( sph != 0 && spl != 0 );
  63         }
  64
  65         void Stack::regChanged(IORegister *reg) {
  66                 if( reg == sph )
  67                         setSPH( (unsigned char)*sph );
  68                 else if( reg == spl )
  69                         setSPL( (unsigned char)*spl );
  70         }
  71
  72 }