sdcc/sim/ucsim/src/sims/mos6502.src/inst.cc

   1 /*
   2  * Simulator of microcontrollers (inst.cc)
   3  *
   4  * Copyright (C) 2020 Drotos Daniel
   5  *
   6  * To contact author send email to dr.dkdb@gmail.com
   7  *
   8  */
   9
  10 /* This file is part of microcontroller simulator: ucsim.
  11
  12 UCSIM is free software; you can redistribute it and/or modify
  13 it under the terms of the GNU General Public License as published by
  14 the Free Software Foundation; either version 2 of the License, or
  15 (at your option) any later version.
  16
  17 UCSIM is distributed in the hope that it will be useful,
  18 but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 GNU General Public License for more details.
  21
  22 You should have received a copy of the GNU General Public License
  23 along with UCSIM; see the file COPYING.  If not, write to the Free
  24 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  25 02111-1307, USA. */
  26
  27 #include "globals.h"
  28
  29 #include "mos6502cl.h"
  30
  31 int
  32 cl_mos6502::NOP(t_mem code)
  33 {
  34   return resGO;
  35 }
  36
  37 int
  38 cl_mos6502::BRK(t_mem code)
  39 {
  40   set_b= true;
  41   PC= (PC+1)&0xffff;//fetch();
  42   cF.W(rF|flagB);
  43   src_brk->request();
  44   return resGO;
  45 }
  46
  47 int
  48 cl_mos6502::RTI(t_mem code)
  49 {
  50   u8_t f;
  51   cSP.W(rSP+1);
  52   f= rom->read(0x0100 + rSP);
  53   f&= ~(0x20|flagB);
  54   cF.W(f);
  55   vc.rd+= 1;
  56   /*cSP.W(rSP+1);
  57   l= rom->read(0x0100 + rSP);
  58   cSP.W(rSP+1);
  59   h= rom->read(0x0100 + rSP);*/
  60   PC= pop_addr();//h*256 + l;
  61   {
  62     class it_level *il= (class it_level *)(it_levels->top());
  63     if (il &&
  64         il->level >= 0)
  65       {
  66         il= (class it_level *)(it_levels->pop());
  67         delete il;
  68       }
  69   }
  70   tick(3);
  71   return resGO;
  72 }
  73
  74 int
  75 cl_mos6502::CLI(t_mem code)
  76 {
  77   cF.W(rF&= ~flagI);
  78   tick(1);
  79   return resGO;
  80 }
  81
  82 int
  83 cl_mos6502::SEI(t_mem code)
  84 {
  85   cF.W(rF|= flagI);
  86   tick(1);
  87   return resGO;
  88 }
  89
  90 int
  91 cl_mos6502::PHP(t_mem code)
  92 {
  93   u8_t v= rF|0x20|flagB;
  94   rom->write(0x0100 + rSP, v);
  95   vc.wr++;
  96   t_addr spbef= rSP;
  97   cSP.W(rSP-1);
  98   class cl_stack_push *op= new cl_stack_push(instPC, v, spbef, rSP);
  99   op->init();
 100   stack_write(op);
 101   tick(2);
 102   return resGO;
 103 }
 104
 105 int
 106 cl_mos6502::CLC(t_mem code)
 107 {
 108   cF.W(rF&= ~flagC);
 109   tick(1);
 110   return resGO;
 111 }
 112
 113 int
 114 cl_mos6502::PLP(t_mem code)
 115 {
 116   t_addr spbef= rSP;
 117   cSP.W(rSP+1);
 118   u8_t v= rom->read(0x0100 + rSP);
 119   v&= ~(0x20|flagB);
 120   class cl_stack_pop *op= new cl_stack_pop(instPC, v, spbef, rSP);
 121   op->init();
 122   stack_read(op);
 123   cF.W(v);
 124   vc.rd++;
 125   tick(3);
 126   return resGO;
 127 }
 128
 129 int
 130 cl_mos6502::SEc(t_mem code)
 131 {
 132   cF.W(rF|= flagC);
 133   tick(1);
 134   return resGO;
 135 }
 136
 137 int
 138 cl_mos6502::PHA(t_mem code)
 139 {
 140   rom->write(0x0100 + rSP, rA);
 141   vc.wr++;
 142   t_addr spbef= rSP;
 143   cSP.W(rSP-1);
 144   class cl_stack_push *op= new cl_stack_push(instPC, rA, spbef, rSP);
 145   op->init();
 146   stack_write(op);
 147   tick(2);
 148   return resGO;
 149 }
 150
 151 int
 152 cl_mos6502::PLA(t_mem code)
 153 {
 154   t_addr spbef= rSP;
 155   cSP.W(rSP+1);
 156   cA.W(rom->read(0x0100 + rSP));
 157   class cl_stack_pop *op= new cl_stack_pop(instPC, rA, spbef, rSP);
 158   op->init();
 159   stack_read(op);
 160   u8_t f= rF & ~(flagN|flagZ);
 161   if (!rA) f|= flagZ;
 162   if (rA&0x80) f|= flagN;
 163   cF.W(f);
 164   vc.rd++;
 165   tick(3);
 166   return resGO;
 167 }
 168
 169 int
 170 cl_mos6502::CLV(t_mem code)
 171 {
 172   cF.W(rF&= ~flagV);
 173   tick(1);
 174   return resGO;
 175 }
 176
 177 int
 178 cl_mos6502::CLD(t_mem code)
 179 {
 180   cF.W(rF&= ~flagD);
 181   tick(1);
 182   return resGO;
 183 }
 184
 185
 186 int
 187 cl_mos6502::SED(t_mem code)
 188 {
 189   cF.W(rF|= flagD);
 190   tick(1);
 191   return resGO;
 192 }
 193
 194
 195 /* End of mos6502.src/inst.cc */