Need Help Converting C Code to Delphi

Below is some C code I'm trying to get working in Delphi but it uses some C stuff I'm not completely clear about in the Delphi world.

Someone please help me convert this to the Delphi equivalent. I'm not concerned with the COM PORT stuff shown; a text box showing the final values is fine for my needs (I'm just looking for a working example):

//CALC CHECKSUM FOR RCVD ASCII STRING, RETURN CHECKSUM VAL 0 = GOOD
//EXAMPLE:
// as00 = 06as0066 (VALID)

// 06 = PKT LEN
// as = PKT CMD
// 00 = PKT VAL
// 66 = CHECKSUM

INT8U itAscRecBuf[82];      
INT8U AscHexToBin(INT8U, INT8U *);
INT8U AsciiToHex( INT8U);      

INT8U CalcCheckSum(void)
{
      INT8U i,length, cc;

      length = AscHexToBin(2, &itAscRecBuf[0]);      //PKT LEN=POS1 & POS2
      cc = AscHexToBin(2, &itAscRecBuf[length]);
      for (i=0;i<length ;i++ )
      {
            cc += itAscRecBuf[i];
      }
      return(cc);      //GOOD CHECKSUM = 0
}

INT8U AscHexToBin(INT8U Width, INT8U * DataPtr)
{
      INT8U aVal;

      aVal = AsciiToHex(*DataPtr);
      DataPtr++;
      if (Width == 2)
      {
            aVal = aVal << 4;
            aVal += AsciiToHex(*DataPtr);
      }
      return(aVal);
}

INT8U AsciiToHex( INT8U Value )
{
      switch ( Value )
      {
            case 'A':
                  return( 10 );
            case 'B':
                  return( 11 );
            case 'C':
                  return( 12 );
            case 'D':
                  return( 13 );
            case 'E':
                  return( 14 );
            case 'F':
                  return( 15 );
            default:
                  return( Value - 0x30 );
      }
}

// SEND CHECKSUM + CR/LF
// (QUICK USAGE EXAMPLE USING COM PORT)

INT8U NibToAsc(INT8U);

void SendChecksum(INT8U CC)
{
      CC = (CC ^ 0xFF) + 1;
      Comm2_Put_Ch(NibToAsc(CC >> 4));
      Comm2_Put_Ch(NibToAsc(CC & 0x0F));
      Comm2_Put_Ch(0x0D);
      Comm2_Put_Ch(0x0A);
}

INT8U NibToAsc(INT8U Nib)
{
      if (Nib < 0x0A)
            return( (INT8U)(Nib + 0x30));
      else if (Nib <= 0x0F)
            return(Nib + 0x37);
      return(0x20);
}