disa.c

motorola ezx 平台下的fba模拟器

  int ea=0,dir=0;
  char eat[64]="";

  dir=(op>>3)&1;
  ea=(op&7)|8;
  DisaGetEa(eat,ea,0);

  if (dir) sprintf(DisaText,"move usp, %s",eat);
  else     sprintf(DisaText,"move %s, usp",eat);
  return 0;
}

// ================ Opcodes 0x4e70+ ================
static int Disa4E70(int op)
{
  char *inst[8]={"reset","nop","stop","rte","rtd","rts","trapv","rtr"};
  int n=0;

  n=op&7;

  sprintf(DisaText,"%s",inst[n]);

  //todo - 'stop' with 16 bit data
  
  return 0;
}

// ================ Opcodes 0x4a00+ ================
static int DisaTst(int op)
{
  // Tst 01001010 xxeeeeee  (eeeeee=ea)
  int ea=0;
  char eat[64]="";
  int size=0;

  ea=op&0x003f;
  DisaGetEa(eat,ea,0);
  size=(op>>6)&3; if (size>=3) return 1;

  sprintf(DisaText,"tst.%c %s",Tasm[size],eat);
  return 0;
}

// ================ Opcodes 0x4e80+ ================
static int DisaJsr(int op)
{
  // Jsr/Jmp 0100 1110 1mEE Eeee (eeeeee=ea m=1=jmp)
  int sea=0;
  char seat[64]="";

  sea=op&0x003f;
  DisaGetEa(seat,sea,0);

  sprintf(DisaText,"j%s %s", op&0x40?"mp":"sr", seat);
  return 0;
}

// ================ Opcodes 0x5000+ ================
static int DisaAddq(int op)
{
  // 0101nnnt xxeeeeee (nnn=#8,1-7 t=addq/subq xx=size, eeeeee=EA)
  int num=0,type=0,size=0,ea=0;
  char eat[64]="";

  num =(op>>9)&7; if (num==0) num=8;
  type=(op>>8)&1;
  size=(op>>6)&3; if (size>=3) return 1;
  ea  = op&0x3f;

  DisaGetEa(eat,ea,size);

  sprintf(DisaText,"%s.%c #%d, %s",type?"subq":"addq",Tasm[size],num,eat);
  return 0;
}

// ================ Opcodes 0x50c0+ ================
static int DisaSet(int op)
{
  // 0101cccc 11eeeeee (sxx ea)
  static char *cond[16]=
  {"t" ,"f", "hi","ls","cc","cs","ne","eq",
   "vc","vs","pl","mi","ge","lt","gt","le"};
  char *cc="";
  int ea=0;
  char eat[64]="";

  cc=cond[(op>>8)&0xf]; // Get condition code
  ea=op&0x3f;
  if ((ea&0x38)==0x08) return 1; // dbra, not scc

  DisaGetEa(eat,ea,0);
  sprintf(DisaText,"s%s %s",cc,eat);
  return 0;
}

// ================ Opcodes 0x50c8+ ================
static int DisaDbra(int op)
{
  // 0101cccc 11001nnn offset  (dbra/dbxx Rn,offset)
  int dea=0; char deat[64]="";
  int pc=0,Offset=0;

  static char *BraCode[16]=
  {"bt" ,"bra","bhi","bls","bcc","bcs","bne","beq",
   "bvc","bvs","bpl","bmi","bge","blt","bgt","ble"};
  char *Bra="";

  dea=op&7;
  DisaGetEa(deat,dea,2);

  // Get condition code
  Bra=BraCode[(op>>8)&0xf];

  // Get offset
  pc=DisaPc;
  Offset=(short)DisaWord(DisaPc); DisaPc+=2;

  sprintf(DisaText,"d%s %s, %x",Bra,deat,pc+Offset);
  return 0;
}

// ================ Opcodes 0x6000+ ================
static int DisaBranch(int op)
{
  // Branch 0110cccc nn  (cccc=condition)
  int pc=0,Offset=0;

  static char *BraCode[16]=
  {"bra","bsr","bhi","bls","bcc","bcs","bne","beq",
   "bvc","bvs","bpl","bmi","bge","blt","bgt","ble"};
  char *Bra="";

  // Get condition code
  Bra=BraCode[(op>>8)&0x0f];

  // Get offset
  pc=DisaPc;
  Offset=(char)(op&0xff);
       if (Offset== 0) { Offset=(short)DisaWord(DisaPc); DisaPc+=2; }
  else if (Offset==-1) { Offset=       DisaLong(DisaPc); DisaPc+=4; }

  sprintf(DisaText,"%s %x",Bra,pc+Offset);
  return 0;
}

// ================ Opcodes 0x7000+ ================
static int DisaMoveq(int op)
{
  // Moveq 0111rrr0 nn (rrr=Dest register, nn=data)

  int dea=0; char deat[64]="";
  char *inst="moveq";
  int val=0;

  dea=(op>>9)&7;
  DisaGetEa(deat,dea,2);

  val=(char)(op&0xff);
  sprintf(DisaText,"%s #$%x, %s",inst,val,deat);
  return 0;
}

// ================ Opcodes 0x8000+ ================
static int DisaArithReg(int op)
{
  // 1t0tnnnd xxeeeeee (tt=type:or/sub/and/add xx=size, eeeeee=EA)
  int type=0,size=0,dir=0,rea=0,ea=0;
  char reat[64]="",eat[64]="";
  char *opcode[]={"or","sub","","","and","add"};

  type=(op>>12)&5;
  rea =(op>> 9)&7;
  dir =(op>> 8)&1;
  size=(op>> 6)&3; if (size>=3) return 1;
  ea  = op&0x3f;

  if (dir && ea<0x10) return 1; // addx opcode

  DisaGetEa(reat,rea,size);
  DisaGetEa( eat, ea,size);

  if (dir) sprintf(DisaText,"%s.%c %s, %s",opcode[type],Tasm[size],reat,eat);
  else     sprintf(DisaText,"%s.%c %s, %s",opcode[type],Tasm[size],eat,reat);
  return 0;
}

// ================ Opcodes 0x8100+ ================
static int DisaAbcd(int op)
{
  // 1t00ddd1 0000asss - sbcd/abcd Ds,Dd or -(As),-(Ad)
  int type=0;
  int dn=0,addr=0,sn=0;
  char *opcode[]={"sbcd","abcd"};

  type=(op>>14)&1;
  dn  =(op>> 9)&7;
  addr=(op>> 3)&1;
  sn  = op     &7;

  if (addr) sprintf(DisaText,"%s -(a%d), -(a%d)",opcode[type],sn,dn);
  else      sprintf(DisaText,"%s d%d, d%d",       opcode[type],sn,dn);

  return 0;
}

// ================ Opcodes 0x80c0+ ================
static int DisaMul(int op)
{
  // Div/Mul: 1m00nnns 11eeeeee (m=Mul, nnn=Register Dn, s=signed, eeeeee=EA)
  int type=0,rea=0,sign=0,ea=0,size=1;
  char reat[64]="",eat[64]="";
  char *opcode[2]={"div","mul"};

  type=(op>>14)&1; // div/mul
  rea =(op>> 9)&7;
  sign=(op>> 8)&1;
  ea  = op&0x3f;

  DisaGetEa(reat,rea,size);
  DisaGetEa( eat, ea,size);

  sprintf(DisaText,"%s%c.%c %s, %s",opcode[type],sign?'s':'u',Tasm[size],eat,reat);
  return 0;
}

// ================ Opcodes 0x90c0+ ================
static int DisaAritha(int op)
{
  // Suba/Cmpa/Adda 1tt1nnnx 11eeeeee (tt=type, x=size, eeeeee=Source EA)
  int type=0,size=0,sea=0,dea=0;
  char seat[64]="",deat[64]="";
  char *aritha[4]={"suba","cmpa","adda",""};

  type=(op>>13)&3; if (type>=3) return 1;
  size=(op>>8)&1; size++;
  dea =(op>>9)&7; dea|=8; // Dest=An
  sea = op&0x003f; // Source

  DisaGetEa(seat,sea,size);
  DisaGetEa(deat,dea,size);

  sprintf(DisaText,"%s.%c %s, %s",aritha[type],Tasm[size],seat,deat);
  return 0;
}

// ================ Opcodes 0xb000+ ================
static int DisaCmpEor(int op)
{
  // Cmp/Eor 1011rrrt xxeeeeee (rrr=Dn, t=cmp/eor, xx=size extension, eeeeee=ea)
  char reat[64]="",eat[64]="";
  int type=0,size=0;

  type=(op>>8)&1;
  size=(op>>6)&3; if (size>=3) return 1;
  if ((op&0xf138)==0xb108) return 1; // cmpm opcode 
  
  DisaGetEa(reat,(op>>9)&7,size);
  DisaGetEa(eat,  op&0x3f, size);

  if (type) sprintf(DisaText,"eor.%c %s, %s",Tasm[size],reat,eat);
  else      sprintf(DisaText,"cmp.%c %s, %s",Tasm[size],eat,reat);
  return 0;
}

// ================ Opcodes 0xb108+ ================
static int DisaCmpm(int op)
{
  // Cmpm  1011ddd1 xx001sss
  int type=0,size=0,dea=0,sea=0;
  char deat[64]="",seat[64]="";

  type=(op>>12)&5;
  dea =(op>> 9)&7; dea|=8;
  size=(op>> 6)&3; if (size>=3) return 1;
  sea  = op&0x3f;

  DisaGetEa(deat,dea,size);
  DisaGetEa(seat,sea,size);

  sprintf(DisaText,"cmpm.%c (%s)+, (%s)+",Tasm[size],seat,deat);

  return 0;
}

// ================ Opcodes 0xc140+ ================
// 1100ttt1 01000sss  exg ds,dt
// 1100ttt1 01001sss  exg as,at
// 1100ttt1 10001sss  exg as,dt
static int DisaExg(int op)
{
  int tr=0,type=0,sr=0;

  tr  =(op>>9)&7;
  type= op&0xf8;
  sr  = op&7;

       if (type==0x40) sprintf(DisaText,"exg d%d, d%d",sr,tr);
  else if (type==0x48) sprintf(DisaText,"exg a%d, a%d",sr,tr);
  else if (type==0x88) sprintf(DisaText,"exg a%d, d%d",sr,tr);
  else return 1;

  return 0;
}

// ================ Opcodes 0xd100+ ================
static int DisaAddx(int op)
{
  // 1t01ddd1 xx000sss addx
  int type=0,size=0,dea=0,sea=0;
  char deat[64]="",seat[64]="";
  char *opcode[6]={"","subx","","","","addx"};

  type=(op>>12)&5;
  dea =(op>> 9)&7;
  size=(op>> 6)&3; if (size>=3) return 1;
  sea  = op&0x3f;

  DisaGetEa(deat,dea,size);
  DisaGetEa(seat,sea,size);

  sprintf(DisaText,"%s.%c %s, %s",opcode[type],Tasm[size],seat,deat);
  return 0;
}

// ================ Opcodes 0xe000+ ================
static char *AsrName[4]={"as","ls","rox","ro"};
static int DisaAsr(int op)
{
  // Asr/l/Ror/l etc - 1110cccd xxuttnnn
  // (ccc=count, d=direction xx=size extension, u=use reg for count, tt=type, nnn=register Dn)
  int count=0,dir=0,size=0,usereg=0,type=0,num=0;

  count =(op>>9)&7;
  dir   =(op>>8)&1;
  size  =(op>>6)&3; if (size>=3) return 1; // todo Asr EA
  usereg=(op>>5)&1;
  type  =(op>>3)&3;
  num   = op    &7; // Register number

  if (usereg==0) count=((count-1)&7)+1; // because ccc=000 means 8

  sprintf(DisaText,"%s%c.%c %c%d, d%d",
    AsrName[type], dir?'l':'r', Tasm[size],
    usereg?'d':'#', count, num);
  return 0;
}

static int DisaAsrEa(int op)
{
  // Asr/l/Ror/l etc EA - 11100ttd 11eeeeee 
  int type=0,dir=0,size=1;
  char eat[64]="";

  type=(op>>9)&3;
  dir =(op>>8)&1;
  DisaGetEa(eat,op&0x3f,size);

  sprintf(DisaText,"%s%c.w %s", AsrName[type], dir?'l':'r', eat);
  return 0;
}

// =================================================================

static int TryOp(int op)
{
  if ((op&0xf100)==0x0000) DisaArithImm(op); // Ori/And/Sub/Add/Eor/Cmp Immediate
  if ((op&0xf5bf)==0x003c) DisaArithSr(op); // Ori/Andi/Eori $nnnn,sr
  if ((op&0xf100)==0x0100) DisaBtstReg(op);
  if ((op&0xf138)==0x0108) DisaMovep(op);
  if ((op&0xff00)==0x0800) DisaBtstImm(op); // Btst/Bchg/Bclr/Bset
  if ((op&0xc000)==0x0000) DisaMove(op);
  if ((op&0xf900)==0x4000) DisaNeg(op); // Negx/Clr/Neg/Not
  if ((op&0xf1c0)==0x41c0) DisaLea(op);
  if ((op&0xf9c0)==0x40c0) DisaMoveSr(op);
  if ((op&0xfff8)==0x4840) DisaSwap(op);
  if ((op&0xffc0)==0x4840) DisaPea(op);
  if ((op&0xffb8)==0x4880) DisaExt(op);
  if ((op&0xfb80)==0x4880) DisaMovem(op);
  if ((op&0xff00)==0x4a00) DisaTst(op);
  if ((op&0xfff0)==0x4e40) DisaTrap(op);
  if ((op&0xfff8)==0x4e50) DisaLink(op);
  if ((op&0xfff8)==0x4e58) DisaUnlk(op);
  if ((op&0xfff0)==0x4e60) DisaMoveUsp(op);
  if ((op&0xfff8)==0x4e70) Disa4E70(op);
  if ((op&0xff80)==0x4e80) DisaJsr(op);
  if ((op&0xf000)==0x5000) DisaAddq(op);
  if ((op&0xf0c0)==0x50c0) DisaSet(op);
  if ((op&0xf0f8)==0x50c8) DisaDbra(op);
  if ((op&0xf000)==0x6000) DisaBranch(op);
  if ((op&0xa000)==0x8000) DisaArithReg(op); // Or/Sub/And/Add
  if ((op&0xb1f0)==0x8100) DisaAbcd(op);
  if ((op&0xb130)==0x9100) DisaAddx(op);
  if ((op&0xb0c0)==0x80c0) DisaMul(op);
  if ((op&0xf100)==0x7000) DisaMoveq(op);
  if ((op&0x90c0)==0x90c0) DisaAritha(op);
  if ((op&0xf000)==0xb000) DisaCmpEor(op);
  if ((op&0xf138)==0xb108) DisaCmpm(op);
  if ((op&0xf130)==0xc100) DisaExg(op);
  if ((op&0xf000)==0xe000) DisaAsr(op);
  if ((op&0xf8c0)==0xe0c0) DisaAsrEa(op);

  // Unknown opcoode
  return 0;
}

int DisaGet()
{
  int op=0;
  if (DisaWord==NULL) return 1;

  Comment[0]=0;
  DisaText[0]=0; // Assume opcode unknown

  op=DisaWord(DisaPc)&0xffff; DisaPc+=2;
  TryOp(op);
  strcat(DisaText,Comment);

  // Unknown opcoode
  return 0;
}