decoder.c

win32program disassembler

      case 15: r=op();     if(!r) return 0; x=result; // wait group
               i_opclass=15; i_opcode=x;
               b=PeekOneByte();
               if (b==217)
               {
                  b=PeekSecondByte();
                  if (regTable[b]==6||regTable[b]==7)
                  {
                     r=op();    if(!r) return 0; y=result;
                     r=opext(); if(!r) return 0;
                     i_opcode=y; prefixStack[i_psp++]=x;
                  }
               }
               else if (b==219)
               {
                  b=PeekSecondByte();
                  if (b==226||b==227)
                  {
                     r=op();    if(!r) return 0; y1=result;
                     r=op();    if(!r) return 0; y2=result;
                     i_opcode=y1; i_mod=y2; prefixStack[i_psp++]=x;   
                  }
               }
               else if (b==221)
               {
                  b=PeekSecondByte();
                  if (regTable[b]==6||regTable[b]==7)
                  {
                     r=op();    if(!r) return 0; y=result;
                     r=opext(); if(!r) return 0;
                     i_opcode=y; prefixStack[i_psp++]=x;
                  }
               }
               else if (b==223)
               {
                  b=PeekSecondByte();
                  if (b==224)
                  {
                     r=op();    if(!r) return 0; y1=result;
                     r=op();    if(!r) return 0; y2=result;
                     i_opcode=y1; i_mod=y2; prefixStack[i_psp++]=x;
                  }
               }
               break;
      case 16: r=op();     if(!r) return 0; x=result; // repeat group
               if (x==242)
               {
                  while(prefixes());
                  b=PeekOneByte();
                  if (repeatgroupTable[b]==1)
                  {
                     r=op();      if(!r) return 0; y=result;
                     i_opclass=16; i_opcode=y; prefixStack[i_psp++]=x;
                  }
                  else return 0;
               }
               else
               {
                  while(prefixes());
                  b=PeekOneByte();
                  if (repeatgroupTable[b]>0)
                  {
                     r=op();      if(!r) return 0; y=result;
                     i_opclass=16; i_opcode=y; prefixStack[i_psp++]=x;  
                  }
                  else return 0;
               }
               break;
      default: return 0;
   }
   return 1;
}
int twobyteinstr()
{
int r, b, x, y;
   b=PeekOneByte();
   switch(opcode2Table[b])
   {
      case 0: r=op();     if(!r) return 0; x=result;
              i_opclass=0; i_opcode=x;
              break;
      case 1: r=op();     if(!r) return 0; x=result;
              r=adword(); if(!r) return 0; y=result;
              i_opclass=1; i_opcode=x; i_dword=y;
              break;
      case 2: r=op();     if(!r) return 0; x=result;
              r=modrm();  if(!r) return 0;
              i_opclass=2; i_opcode=x;
              break;
      case 3: r=op();     if(!r) return 0; x=result;
              r=modrm();  if(!r) return 0;
              r=byte();   if(!r) return 0; y=result;
              i_opclass=3; i_opcode=x; i_byte=y;
              break;
      case 4: r=op();     if(!r) return 0; x=result;
              r=opext();  if(!r) return 0;
              i_opclass=4; i_opcode=x;
              break;
      case 5: r=op();     if(!r) return 0; x=result;
              r=opext();  if(!r) return 0;
              r=byte();   if(!r) return 0; y=result;
              i_opclass=5; i_opcode=x; i_byte=y;
              break;
      default:
              return 0;
   }
   return 1;
}
int modrm()
{
        if (addressOveride==0) return modrm1();
   else if (addressOveride==1) return modrm2();
   else return 0;
}
int modrm1()
{
int  r, b, x, y, y1, y2;

   b=PeekOneByte();
   switch(modTable[b])
   {
      case 1: r=op();    if(!r) return 0; x=result;
              i_mod=x;
              break;
      case 2: r=op();    if(!r) return 0; x=result;
              r=op();    if(!r) return 0; y=result;
              i_mod=x;   i_sib=y;
              if (sibTable[y]==1)
              {
                 r=dword(); if(!r) return 0; y1=result;
                 m_dword=y1;
              }
              break;
      case 3: r=op();    if(!r) return 0; x=result;
              r=dword(); if(!r) return 0; y=result;
              i_mod=x;      m_dword=y;
              break;
      case 4: r=op();    if(!r) return 0; x=result;
              r=byte();  if(!r) return 0; y=result;
              i_mod=x;     m_byte=y;
              break;
      case 5: r=op();    if(!r) return 0; x=result;
              r=sib();   if(!r) return 0; y1=result;
              r=byte();  if(!r) return 0; y2=result;
              i_mod=x;     i_sib=y1; m_byte=y2;
              break;
      case 6: r=op();    if(!r) return 0; x=result;
              r=dword(); if(!r) return 0; y=result;
              i_mod=x;     m_dword=y;
              break;
      case 7: r=op();    if(!r) return 0; x=result;
              r=sib();   if(!r) return 0; y1=result;
              r=dword(); if(!r) return 0; y2=result;
              i_mod=x;     i_sib=y1; m_dword=y2;
              break;
      case 8: r=op();    if(!r) return 0; x=result;
              i_mod=x;
              break;
      default: return 0;
   }
   return 1;
}
int modrm2()
{
int  r, b, x, y;
   b=PeekOneByte();
   switch(mod16Table[b])
   {
      case 1: r=op();   if(!r) return 0; x=result;
              i_mod=x;
              break;
      case 2: r=op();   if(!r) return 0; x=result;
              r=word(); if(!r) return 0; y=result;
              i_mod=x;  m_dword=y;
              break;
      case 3: r=op();   if(!r) return 0; x=result;
              r=byte(); if(!r) return 0; y=result;
              i_mod=x;  m_byte=y;
              break;
      case 4: r=op();   if(!r) return 0; x=result;
              r=word(); if(!r) return 0; y=result;
              i_mod=x;  m_dword=y;
              break;
      case 5: r=op();   if(!r) return 0; x=result;
              i_mod=x;
              break;
      default: return 0;
   }
   return 1;
}
int sib()
{
   return byte();
}
int labelstartposition()
{
int r;
   r=dword(); if(!r) return 0;
   m_dword=result;
   label_start_pos=(DWORD)m_dword;
   opclass=1;
   if(nextMode>0)bodyprint0();
   return 1;
}
int label1()
{
DWORD r, rr, s;
   // I like to give this guy some more priority or power to overide some constraints
   // namely It is worth try to find label blocks.... I guess
   r=label_start_pos+4;s=r;
   while (isLabelCheckable(r))
   {
       rr=(DWORD)getIntFile(r);
       if (!isGoodAddress(rr)) return 1;
       i_col=4;
       pushTrace(305);
       if (nextMode>0) EnterLabel(166, rr, r); 
       popTrace();
       r+=4;
   }
   return 1;
}
int opext()
{
   return modrm();
}
int opextg()
{
   return opext();
}
//...................................................................

/* globals */

int             fatalError = 0;         // flow control
int             errorcount = 0;         // to use counting errors
int             GotEof=0;
int             yyfirsttime=1;
unsigned char   c;
PBYTE           yyfp, yypmax;

int ReadOneByte()
{
    if (yyfirsttime)
    {
        yyfirsttime=0; GotEof=0; 
        yyfp   = (PBYTE)((int)lpFile + vCodeOffset);
        yypmax = (PBYTE)((int)lpFile + CodeOffset + CodeSize);
    }                                                       
    if (GotEof) return EOF;
    c = *yyfp++;
    if (yyfp >= yypmax ) {GotEof = 1;}
    return (int)c;
}
int PeekOneByte()
{
    if (yyfirsttime)
        return  (int) c = *(PBYTE)((int)lpFile + vCodeOffset);
    if (GotEof) return EOF;
    if (yyfp >= yypmax ) return EOF; 
    else return (int) c = *(yyfp);
}
int PeekSecondByte()
{
    if (GotEof) return EOF;
    if (yyfp+1 >= yypmax ) return EOF; 
    else return (int) c = *(yyfp+1);
}