Programming Embedded Systems in C and C++

The Zilog 85230 Serial Controller 137

/**********************************************************************

*

* Method: gets()

*

* Description: Collects a string of characters terminated by a new-

* line character from the serial port and places it in s.

* The newline character is replaced by a null character.

*

* Notes: The caller is responsible for allocating adequate space

* for the string.

*

* Warnings: This function does not block waiting for a newline.

* If a complete string is not found, it will return

* whatever is available in the receive queue.

*

* Returns: A pointer to the string.

* Otherwise, NULL is returned to indicate an error.

*

**********************************************************************/

char *

SerialPort::gets(char * s)

{

char * p;

int c;

//

// Read characters until a newline is found or no more data.

//

for (p = s; (c = getchar()) != '\n' && c >= 0; p++)

{

*p = c;

}

//

// Terminate the string.

//

*p = '\0';

return (s);

} /* gets() */

The Zilog 85230 Serial Controller

The two serial ports on the Arcom board are part of the same Zilog 85230 Serial

Communications Controller. This particular chip is, unfortunately, rather compli-

cated to configure and use. So, rather than fill up the SerialPort class shown

earlier with device-specific code, I decided to divide the serial driver into two

parts. The upper layer is the class we have just discussed. This upper