ESCAPE C-3

escape, getkey, escin, escout - send and receive terminal escape sequences

Escape sends to standard output the escape sequence specified by the function parameter. The functions performed by escape are defined as constants in the include file <cbase/escape.h>. As a special case, the MOVCUR function (move cursor) has two extra parameters that specify the row and column of where to move the cursor. Row and column numbers start at 1. Row 1 is the topmost row on the terminal screen. Column 1 is the leftmost column.

Some terminals may not be able to perform all the defined functions. For example, some terminals cannot perform INSLINE or DELLINE. If no escape sequence is defined for a particular function, escape returns a negative value. If the function can be performed by escape, it returns a positive value.

The escout function tests whether a function is defined for the terminal. If escout returns a non-zero value for a function, an escape sequence is defined for that function. If it returns a zero value, no escape sequence is defined for that function.

The escin function tests whether an input key is defined for the terminal. It returns a non-zero value if the input key is defined, and zero if it is not defined.

Getkey reads terminal key strokes from standard input and returns their ASCII integer equivalent. Its function is analogous to the getchar(3) function in the standard I/O library. In addition, getkey translates escape sequences that are typed and returns the corresponding integer equivalent. The integer constants that are returned are defined in the include file <cbase/escape.h>; for example, UPARROW and DELLINE.

If you wish to use escape sequences defined in a terminal definition file, you must set the environment string TERM to the name of a terminal type defined in the terminal definition directory. This is normally done by executing

before starting any command that uses escape or getkey. Any program using escape or getkey should call the ttyinit (C-3) function to initialize the terminal, and call the ttyrestore function to restore the terminal before exiting. If TERM is not set, ttyinit uses an internal terminal definition for PC's that calls ROM BIOS routines instead of using a terminal definition file.

Escape and getkey provide a method for using CRT terminals in a terminal independent manner. A program using escape and getkey need not be concerned with the exact escape sequences necessary to perform terminal functions.

ttyinit(C-3), ttyrestore(C-3), termparm(C-3)

Chapter 2,

C/Base Reference Manual Chapter 11, "Creating Terminal Definitions"