oparith.cpp

motorola ezx 平台下的fba模拟器

  if (type)
  {
    ot("  mov r3,#0x00f00000\n");
    ot("  ldrb r0,[r7,#0x45] ;@ Get X bit\n");
	ot("  tst r0,#2\n");
    ot("  and r0,r3,r10,lsr #4\n");
    ot("  and r2,r3,r1,lsr #4\n");
    ot("  add r0,r0,r2\n");
    ot("  addne r0,r0,#0x00100000\n");
//    ot("  tst r0,#0x00800000\n");
//    ot("  orreq r9,r9,#0x01000000 ;@ Undefined V behavior\n");
    ot("  cmp r0,#0x00900000\n");
    ot("  addhi r0,r0,#0x00600000 ;@ Decimal adjust units\n");

    ot("  mov r2,r1,lsr #28\n");
    ot("  add r0,r0,r2,lsl #24\n");
    ot("  mov r2,r10,lsr #28\n");
    ot("  add r0,r0,r2,lsl #24\n");
    ot("  cmp r0,#0x09900000\n");
	ot("  orrhi r9,r9,#0x20000000 ;@ C\n");
	ot("  subhi r0,r0,#0x0a000000\n");
//	ot("  and r3,r9,r0,lsr #3 ;@ Undefined V behavior part II\n");
//	ot("  orr r9,r9,r3,lsl #4 ;@ V\n");
    ot("  movs r0,r0,lsl #4\n");
	ot("  orrmi r9,r9,#0x90000000 ;@ Undefined N+V behavior\n"); // this is what Musashi really does
	ot("  bicne r9,r9,#0x40000000 ;@ Z flag\n");
  }
  else
  {
    ot("  mov r3,#0x00f00000\n");
    ot("  ldrb r0,[r7,#0x45] ;@ Get X bit\n");
	ot("  tst r0,#2\n");
    ot("  and r0,r3,r1,lsr #4\n");
    ot("  and r2,r3,r10,lsr #4\n");
    ot("  sub r0,r0,r2\n");
    ot("  subne r0,r0,#0x00100000\n");
//    ot("  tst r0,#0x00800000\n");
//    ot("  orreq r9,r9,#0x01000000 ;@ Undefined V behavior\n");
    ot("  cmp r0,#0x00900000\n");
    ot("  subhi r0,r0,#0x00600000 ;@ Decimal adjust units\n");

    ot("  mov r2,r1,lsr #28\n");
    ot("  add r0,r0,r2,lsl #24\n");
    ot("  mov r2,r10,lsr #28\n");
    ot("  sub r0,r0,r2,lsl #24\n");
    ot("  cmp r0,#0x09900000\n");
	ot("  orrhi r9,r9,#0xa0000000 ;@ N and C\n");
	ot("  addhi r0,r0,#0x0a000000\n");
//	ot("  and r3,r9,r0,lsr #3 ;@ Undefined V behavior part II\n");
//	ot("  orr r9,r9,r3,lsl #4 ;@ V\n");
    ot("  movs r0,r0,lsl #4\n");
//	ot("  orrmi r9,r9,#0x80000000 ;@ Undefined N behavior\n");
	ot("  bicne r9,r9,#0x40000000 ;@ Z flag\n");
  }

  ot("  mov r2,r9,lsr #28\n");
  ot("  strb r2,[r7,#0x45] ;@ Save X bit\n");

  EaWrite(11,     0, dea,0,0x0e00,1);
  OpEnd();

  return 0;
}

// 01008000 00eeeeee - nbcd <ea>
int OpNbcd(int op)
{
  int use=0;
  int ea=0;
  
  ea=op&0x3f;

  if(EaCanWrite(ea)==0||EaAn(ea)) return 1;

  use=OpBase(op);
  if(op!=use) { OpUse(op,use); return 0; } // Use existing handler

  OpStart(op); Cycles=6;
  if(ea >= 8)  Cycles+=2;

  EaCalc(10,0x3f, ea,0,1);
  EaRead(10,   0, ea,0,0x3f,1);

  // this is rewrite of Musashi's code
  ot("  ldrb r2,[r7,#0x45]\n");
  ot("  tst r2,#2\n");
  ot("  mov r2,r0\n");
  ot("  addne r2,r0,#0x01000000 ;@ add X\n");
  ot("  rsbs r1,r2,#0x9a000000 ;@ do arithmetic\n");

  ot("  bic r9,r9,#0xb0000000 ;@ clear all flags, except Z\n");
  ot("  orrmi r9,r9,#0x80000000 ;@ N\n");
  ot("  cmp r1,#0x9a000000\n");
  ot("  beq finish%.4x\n",op);
  ot("\n");

  ot("  mvn r3,r9,lsr #3 ;@ Undefined V behavior\n",op);
  ot("  and r2,r1,#0x0f000000\n");
  ot("  cmp r2,#0x0a000000\n");
  ot("  andeq r1,r1,#0xf0000000\n");
  ot("  addeq r1,r1,#0x10000000\n");
  ot("  and r3,r3,r1,lsr #3 ;@ Undefined V behavior part II\n",op);
  ot("  tst r1,r1\n");
  ot("  orr r9,r9,r3 ;@ save V\n",op);
  ot("  bicne r9,r9,#0x40000000 ;@ Z\n");
  ot("  orr r9,r9,#0x20000000 ;@ C\n");
  ot("\n");

  EaWrite(10,     1, ea,0,0x3f,1);

  ot("finish%.4x%s\n",op,ms?"":":");
  ot("  mov r2,r9,lsr #28\n");
  ot("  strb r2, [r7,#0x45]\n");

  OpEnd();

  return 0;
}

// --------------------- Opcodes 0x90c0+ ---------------------
// Suba/Cmpa/Adda 1tt1nnnx 11eeeeee (tt=type, x=size, eeeeee=Source EA)
int OpAritha(int op)
{
  int use=0;
  int type=0,size=0,sea=0,dea=0;

  // Suba/Cmpa/Adda/(invalid):
  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

  // See if we can do this opcode:
  if (EaCanRead(sea,size)==0) return 1;

  use=OpBase(op);
  use&=~0x0e00; // Use same opcode for An
  if (op!=use) { OpUse(op,use); return 0; } // Use existing handler

  OpStart(op); Cycles=(size==2)?6:8;
  if(size==2&&(sea<0x10||sea==0x3c)) Cycles+=2;
  if(type==1) Cycles=6;

  
  EaCalc ( 0,0x003f, sea,size);
  EaRead ( 0,    10, sea,size,0x003f);

  EaCalc ( 0,0x0e00, dea,2,1);
  EaRead ( 0,     1, dea,2,0x0e00);

  if (type==0) ot("  sub r1,r1,r10\n");
  if (type==1) ot("  cmp r1,r10 ;@ Defines NZCV\n");
  if (type==1) OpGetFlags(1,0); // Get Cmp flags
  if (type==2) ot("  add r1,r1,r10\n");
  ot("\n");
  
  if (type!=1) EaWrite( 0,     1, dea,2,0x0e00,1);

  OpEnd();

  return 0;
}

// --------------------- Opcodes 0x9100+ ---------------------
// Emit a Subx/Addx opcode, 1t01ddd1 zz00rsss addx.z Ds,Dd
int OpAddx(int op)
{
  int use=0;
  int type=0,size=0,dea=0,sea=0,mem=0;

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

  // See if we can do this opcode:
  if (EaCanRead(sea,size)==0) return 1;
  if (EaCanWrite(dea)==0) return 1;

  if(mem) { sea+=0x20; dea+=0x20; }

  use=op&~0x0e07; // Use same opcode for Dn
  if (size==0&&(sea==0x27||dea==0x27)) use=op; // ___x.b -(a7)
  if (op!=use) { OpUse(op,use); return 0; } // Use existing handler

  OpStart(op);  Cycles=4;
  if(size>=2)   Cycles+=4;
  if(sea>=0x10) Cycles+=2;

  ot(";@ Get r10=EA r11=EA value\n");
  EaCalc( 0,0x0007,sea,size,1);
  EaRead( 0,    11,sea,size,0x0007,1);
  ot(";@ Get r0=Register r1=Register value\n");
  EaCalc( 0,0x0e00,dea,size,1);
  EaRead( 0,     1,dea,size,0x0e00,1);

  ot(";@ Do arithmetic:\n");
  GetXBit(type==1);

  if (type==5 && size<2)
  {
    ot(";@ Make sure the carry bit will tip the balance:\n");
	ot("  mvn r2,#0\n");
    ot("  orr r11,r11,r2,lsr #%i\n",(size==0)?8:16);
    ot("\n");
  }

  if (type==1) ot("  sbcs r1,r1,r11\n");
  if (type==5) ot("  adcs r1,r1,r11\n");
  ot("  orr r3,r9,#0xb0000000 ;@ for old Z\n");
  OpGetFlags(type==1,1,0); // subtract
  if (size<2) {
    ot("  movs r2,r1,lsr #%i\n", size?16:24);
    ot("  orreq r9,r9,#0x40000000 ;@ add potentially missed Z\n");
  }
  ot("  andeq r9,r9,r3 ;@ fix Z\n");
  ot("\n");

  ot(";@ Save result:\n");
  EaWrite( 0, 1, dea,size,0x0e00,1);

  OpEnd();

  return 0;
}

// --------------------- Opcodes 0xb000+ ---------------------
// Emit a Cmp/Eor opcode, 1011rrrt xxeeeeee (rrr=Dn, t=cmp/eor, xx=size extension, eeeeee=ea)
int OpCmpEor(int op)
{
  int rea=0,eor=0;
  int size=0,ea=0,use=0;

  // Get EA and register EA
  rea=(op>>9)&7;
  eor=(op>>8)&1;
  size=(op>>6)&3; if (size>=3) return 1;
  ea=op&0x3f;

  if (eor && (ea>>3) == 1) return 1; // not a valid mode for eor

  // See if we can do this opcode:
  if (EaCanRead(ea,size)==0) return 1;
  if (eor && EaCanWrite(ea)==0) return 1;
  if (EaAn(ea)&&(eor||size==0)) return 1;

  use=OpBase(op);
  use&=~0x0e00; // Use 1 handler for register d0-7
  if (op!=use) { OpUse(op,use); return 0; } // Use existing handler

  OpStart(op); Cycles=4;
  if(eor) {
    if(ea>8)     Cycles+=4;
    if(size>=2)  Cycles+=4;
  } else {
    if(size>=2)  Cycles+=2;
  }

  ot(";@ Get EA into r10 and value into r0:\n");
  EaCalc (10,0x003f,  ea,size,1);
  EaRead (10,     0,  ea,size,0x003f,1);

  ot(";@ Get register operand into r1:\n");
  EaCalc (1, 0x0e00, rea,size,1);
  EaRead (1,      1, rea,size,0x0e00,1);

  ot(";@ Do arithmetic:\n");
  if (eor==0) ot("  cmp r1,r0\n");
  if (eor)
  {
    ot("  eor r1,r0,r1\n");
    ot("  adds r1,r1,#0 ;@ Defines NZ, clears CV\n");
  }

  OpGetFlags(eor==0,0); // Cmp like subtract
  ot("\n");

  if (eor) EaWrite(10, 1,ea,size,0x003f,1);

  OpEnd();
  return 0;
}

// Emit a Cmpm opcode, 1011ddd1 xx001sss (rrr=Adst, xx=size extension, sss=Asrc)
int OpCmpm(int op)
{
  int size=0,sea=0,dea=0,use=0;

  // get size, get EAs
  size=(op>>6)&3; if (size>=3) return 1;
  sea=(op&7)|0x18;
  dea=(op>>9)&0x3f;

  use=op&~0x0e07; // Use 1 handler for all registers..
  if (size==0&&(sea==0x1f||dea==0x1f)) use=op; // ..except (a7)+
  if (op!=use) { OpUse(op,use); return 0; } // Use existing handler

  OpStart(op); Cycles=4;

  ot(";@ Get src operand into r10:\n");
  EaCalc (0,0x000f, sea,size,1);
  EaRead (0,    10, sea,size,0x000f,1);

  ot(";@ Get dst operand into r0:\n");
  EaCalc (0,0x1e00, dea,size,1);
  EaRead (0,     0, dea,size,0x1e00,1);

  ot("  cmp r0,r10\n");
  OpGetFlags(1,0); // Cmp like subtract

  OpEnd();
  return 0;
}


// Emit a Chk opcode, 0100ddd1 x0eeeeee (rrr=Dn, x=size extension, eeeeee=ea)
int OpChk(int op)
{
  int rea=0;
  int size=0,ea=0,use=0;

  // Get EA and register EA
  rea=(op>>9)&7;
  if((op>>7)&1)
       size=1; // word operation
  else size=2; // long
  ea=op&0x3f;

  if (EaAn(ea)) return 1; // not a valid mode
  if (size!=1)  return 1; // 000 variant only supports word

  // See if we can do this opcode:
  if (EaCanRead(ea,size)==0) return 1;

  use=OpBase(op);
  use&=~0x0e00; // Use 1 handler for register d0-7
  if (op!=use) { OpUse(op,use); return 0; } // Use existing handler

  OpStart(op); Cycles=10;

  ot(";@ Get EA into r10 and value into r0:\n");
  EaCalc (10,0x003f,  ea,size,1);
  EaRead (10,     0,  ea,size,0x003f,1);

  ot(";@ Get register operand into r1:\n");
  EaCalc (1, 0x0e00, rea,size,1);
  EaRead (1,      1, rea,size,0x0e00,1);

  ot(";@ get flags, including undocumented ones\n");
  ot("  and r3,r9,#0x80000000\n");
  ot("  adds r1,r1,#0 ;@ Defines NZ, clears CV\n");
  OpGetFlags(0,0);

  ot(";@ is reg negative?\n");
  ot("  bmi chktrap%.4x\n",op);

  ot(";@ Do arithmetic:\n");
  ot("  cmp r1,r0\n");
  ot("  bicgt r9,r9,#0x80000000 ;@ N\n");
  ot("  bgt chktrap%.4x\n",op);

  ot(";@ old N remains\n");
  ot("  bic r9,r9,#0x80000000 ;@ N\n");
  ot("  orr r9,r9,r3\n");
  OpEnd();

  ot("chktrap%.4x%s ;@ CHK exception:\n",op,ms?"":":");
  ot("  mov r0,#0x18\n");
  ot("  bl Exception\n");
  Cycles+=40;
  OpEnd();

  return 0;
}