3c_disasm/instr/shift.cpp

   1 #include "../Iinstr.hpp"
   2
   3 class Cshift : public Iinstr {
   4                 char m_typ;
   5         public:
   6                 Cshift();
   7                 void evalInstr();
   8                 void execInstr();
   9                 std::string toString();
  10                 Iinstr* getNew();
  11 };
  12
  13 /**
  14  * Name:      create_instruction
  15  * Purpose:   if compiled as shared library, this functions creates the
  16               instruction object
  17
  18  * Returns:   pointer to instruction object
  19  */
  20 extern "C" Iinstr* create_instruction() {
  21     return new Cshift();
  22 }
  23
  24 Iinstr* Cshift::getNew()
  25 {
  26         return new Cshift();
  27 }
  28 /**
  29  * Name:      destroy_instruction
  30  * Purpose:   if compiled as shared library, this functions destoys the
  31               instruction object
  32
  33  * Parameter: IInstruction - the instruction object to delete
  34  */
  35 extern "C" void destroy_instruction(Iinstr* p) {
  36     delete p;
  37 }
  38
  39 Cshift::Cshift() : m_typ(0)
  40 {
  41         opcode = B5(01010);
  42         name = "shift";
  43 }
  44
  45 void Cshift::evalInstr()
  46 {
  47         this->m_d = argbits[0];
  48         this->m_c = argbits[1];
  49         argbits >>= 2;
  50
  51         dynamic_bitset<> type = argbits;
  52         type.resize(2);
  53         this->m_typ = type.to_ulong();
  54
  55         switch(this->m_typ) {
  56                 case 1:
  57                         cerr << "INVALID shift type, using logic left shift!" << endl;
  58                         this->m_typ = 0;
  59                 case 0:
  60                         this->name = "lls";
  61                         break;
  62                 case 2:
  63                         this->name = "lrs";
  64                         break;
  65                 case 3:
  66                         this->name = "ars";
  67                         break;
  68                 default:
  69                         cerr << "What have you done? 2 bits that have more than 4 values?!" << endl;
  70         }
  71
  72         argbits >>= 8;
  73         dynamic_bitset<> immb = argbits;
  74         immb.resize(5);
  75         this->m_imm = immb.to_ulong();
  76         argbits >>= 5;
  77         m_ra = this->getRegister(argbits);
  78         argbits >>= 4;
  79         m_rd = this->getRegister(argbits);
  80 }
  81
  82 void Cshift::execInstr()
  83 {
  84         CDatd val = this->m_cpu->getRegister(m_ra);
  85         switch(this->m_typ) {
  86                 case 0:
  87                 case 1:
  88 //                      this->name = "lls";
  89                         for(unsigned int i = 0; i < m_imm; i++) {
  90                                 val = val << 1;
  91                         }
  92                         //carry
  93                         if(m_c) {
  94                                 this->m_cpu->updateCarry(((val >> BIT_LEN) & 0x1) != 0);
  95                         }
  96                         break;
  97                 case 2:
  98 //                      this->name = "lrs";
  99                         {
 100                                 bool carry = this->m_cpu->getCarry();
 101                                 for(unsigned int i = 0; i < m_imm; i++) {
 102                                         val = val >> 1;
 103
 104                                         //carry!
 105                                         //if user wants carry, and carry is set
 106                                         if(this->m_c && carry) {
 107                                                 //set highest bit 1
 108                                                 val |= (CDat)(1<<(BIT_LEN-1));
 109                                         }
 110                                         else {
 111                                                 //set highest bit 0
 112                                                 val &= (~(1<<(BIT_LEN-1)));
 113                                         }
 114                                 }
 115                         }
 116                         break;
 117                 case 3:
 118 //                      this->name = "ars";
 119                         //>> is a ars, but val is CDatd => we have to set the MSB manually
 120                         {
 121                                 bool msb = (val & (1<<(BIT_LEN-1)) >> (BIT_LEN-1));
 122                                 for(unsigned int i = 0; i < m_imm; i++) {
 123                                         val = val >> 1;
 124                                         if(msb) {
 125                                                 //set highest bit 1
 126                                                 val |= (CDat)(1<<(BIT_LEN-1));
 127                                         }
 128                                         else {
 129                                         //set highest bit 0
 130                                         val &= (~(1<<(BIT_LEN-1)));
 131                                         }
 132                                 }
 133                         }
 134                         break;
 135                 default:
 136                         cerr << "What have you done? 2 bits that have more than 4 values?!" << endl;
 137         }
 138         this->m_cpu->setRegister(m_rd, val);
 139 }
 140
 141 std::string Cshift::toString()
 142 {
 143         stringstream op;
 144         op << this->getName();
 145         if(m_c) op << "C";
 146         if(m_d) op << "D";
 147
 148         op << this->getConditionFlag();
 149         op << " r" << m_rd << ", r" << m_ra << ", " << m_imm;
 150         return op.str();
 151 }