New:

UInt_t RanBit(UInt_t hRead)
{

// 
// 

  UInt_t bit7    = (fgShreg & 0x00000040) != 0;
  UInt_t bit28   = (fgShreg & 0x08000000) != 0;
  UInt_t bit29   = (fgShreg & 0x10000000) != 0;
  UInt_t bit30   = (fgShreg & 0x20000000) != 0;

  UInt_t newbit = (bit30 ^ bit29 ^ bit28 ^ bit7) & 0x1;
  fgShreg = ( (hRead == 2 ? newbit : hRead) | (fgShreg << 1 )) & 0x3FFFFFFF;
  return newbit; 

}

//


Old:


UInt_t RanBit(UInt_t hRead)
{

// 
// 

  const UInt_t IB1 = 0x1;	        // Bit 1 mask  000000000000000000000001
  const UInt_t IB3 = 0x4;	        // Bit 3 mask  000000000000000000000100
  const UInt_t IB4 = 0x8;	        // Bit 4 mask  000000000000000000001000
  const UInt_t IB24 = 0x800000;         // Bit 24 mask 100000000000000000000000
  const UInt_t MASK = IB1+IB3+IB4+IB24;	// 100000000000000000001101
 
  int hPred = (fgShreg & IB24) ? 1 : 0;

  if ((hRead == 2 ? hPred : hRead) == 1)
    fgShreg = ((fgShreg ^ MASK) << 1) | IB1;
  else
    fgShreg <<= 1;

  return hPred;
}

//