Category : Files from Magazines
Archive   : PTV1N5.ZIP
Filename : SERIAL.HPP

/**************************************************************************
* SERIAL.HPP - Listing 1
* Written by Kevin D. Weeks, August 1990
* Compiles and runs under Borland Turbo C++ and Zortech C++.
*/
#if !defined(COMM_HPP)
#define COMM_HPP
// the following enum types perform two functions. first, they are checked
// for type by the compiler thus preventing an invalid parameter from
// being passed. second, they function as indices into the tables defined
// at the end of the class definition
enum Com_Port
{ Com_1, Com_2 };
enum Baud_Rate
{ Baud_110, Baud_150, Baud_300, Baud_600, Baud_1200, Baud_2400,
Baud_4800, Baud_9600 };
enum Parity
{ Odd_Parity, Even_Parity, No_Parity };
enum Stop_Bits
{ Stop_Bits_1, Stop_Bits_2 };
enum Data_Bits
{ Data_Bits_7, Data_Bits_8 };
enum Bool
{ FALSE, TRUE };
enum Result
{ OK, ERROR = -1 };
// define a hand-shaking function type
typedef int(*HAND_SHAKE)(int);
// assembly function prototypes
extern "C"
{
Result com_open(int port, unsigned int paramters);
void com_close(void);
int com_read(void *buffer);
Result com_write(int num_bytes, void *buffer);
int com_read_char(void);
Result com_write_char(unsigned char chr);
void com_start_sending(void);
void com_stop_sending(void);
unsigned int com_get_status(void);
int com_chars_recvd(void);
int com_chars_sent(void);
void com_set_buffers(unsigned char *recv_buffer,
unsigned char *send_buffer, int length);
void com_set_handshake(HAND_SHAKE);
void com_clr_recv_buf(void);
void com_clr_send_buf(void);
};
// define the bit flags returned by com_get_status(). note that bits
// 0 - 3 indicate current status, 4 - 7 indicate line errors, and 8 -
// 10 indicate execution errors
typedef union
{
unsigned int value;
struct
{
unsigned port_open : 1;
unsigned char_received : 1;
unsigned sending_message : 1;
unsigned hand_shaking : 1;
unsigned overrun_err : 1;
unsigned parity_err : 1;
unsigned framing_err : 1;
unsigned break_received : 1;
unsigned buffer_overflow : 1;
unsigned invalid_port : 1;
unsigned port_not_found : 1;
} flag;
} Comm_Status;
#define DEFAULT_BUF_SIZE 1024
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* the methods marked with a "// *" will automatically return an error
* unless the port is owned by the current instance of the class */
class Serial_Comm
{
public:
// constructors
Serial_Comm(void);
Serial_Comm(Com_Port port, Baud_Rate baud, Parity par,
Stop_Bits stop, Data_Bits data);
// destructor
~Serial_Comm(void);
// the first group of methods provide for actually accessing data
// they will return an ERROR or -1 if the port is unowned or is
// owned by another instance of the class.
Result open(void);
void close(void);
int read(void *client_buffer);
Result write(void *client_buffer, int length);
int read_char(void);
Result write_char(unsigned char);
// the next two methods allow starting over. note that clr_send_
// buffer will disable sending if sending is enabled. they will
// return an ERROR if another instance owns the port
Result clr_recv_buffer(void);
Result clr_send_buffer(void);
// get_status() returns a 0 if the port is owned by another.
Comm_Status get_status(void);
// the next two methods return an ERROR if the port is owned
// by another instance. in both caes 0 is a valid return value.
int get_bytes_recvd(void);
int get_bytes_sent(void);
// all of the remaining methods will function whether the instance
// in question owns the port or not.
Com_Port get_port(void) { return com_port; };
Baud_Rate get_baud_rate(void) { return baud_rate; };
Parity get_parity(void) { return parity; };
Stop_Bits get_stop_bits(void) { return stop_bits; };
Data_Bits get_data_bits(void) { return data_bits; };
int get_buffer_size(void) { return buffer_size; };
// if the port is open AND owned by the particular instance called
// then it will be closed before the parameters are changed and
// then re-opened. since closing the port will cause anything in
// the send or receive buffers to be discarded these methods
// should be used carefully.
void set_port(Com_Port port);
void set_baud_rate(Baud_Rate baud);
void set_parity(Parity par);
void set_stop_bits(Stop_Bits stop);
void set_data_bits(Data_Bits data);
Result set_buffer_size(int size);
protected:
// the following attributes are shared by all instances of the class
// and descendants.
static Serial_Comm *open_flag;
static unsigned int baud_table[8];
static unsigned int parity_table[3];
static unsigned int stop_table[2];
static unsigned int data_table[2];
private:
// all of these attributes are accessable through methods so keep
// them private.
int buffer_size;
unsigned char *recv_buffer;
unsigned char *send_buffer;
Com_Port com_port;
Baud_Rate baud_rate;
Parity parity;
Stop_Bits stop_bits;
Data_Bits data_bits;
};
#endif