src/vcpu.c


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#include "vcpu.h"
#include "mem.h"
#include "screen.h"


// Current VCPU state
VCPU_State State;

void VCPUInit(){
  State.PC=ADDR_ROM;
}

void VCPUFetch(){
  MemRead((char *)&(State.opcode),2,State.PC);
  State.PC+=2;
}

void VCPUDecode(){
  State.X=(State.opcode<<4) & 0xF0;
  State.Y=(State.opcode<<8) & 0xF0;
  State.N=(State.opcode<<12) & 0xF0;
  State.NN=(State.opcode<<8) & 0xFF;
  State.NNN=(State.opcode<<4) & 0xFFF0;
}

void VCPUExecute(){
  switch(State.opcode & 0xF){
  case 0x0:
    ScreenClear();
    break
      ;;
  case 0x1:
    State.PC=State.NNN;
    break
      ;;
  case 0x6:
    State.V[State.X]=State.NN;
    break
      ;;
  case 0x7:
    State.V[State.X]+=State.NN;
    break
      ;;
  case 0xA:
    State.I=State.NNN;
    break
      ;;

  }
}