10.6 Modules for the Redisplay Mechanism

redisplay-output.c
redisplay-msw.c
redisplay-tty.c
redisplay-x.c
redisplay.c
redisplay.h

These files provide the redisplay mechanism. As with many other subsystems in SXEmacs, there is a clean separation between the general and device-specific support.

redisplay.c contains the bulk of the redisplay engine. These functions update the redisplay structures (which describe how the screen is to appear) to reflect any changes made to the state of any displayable objects (buffer, frame, window, etc.) since the last time that redisplay was called. These functions are highly optimized to avoid doing more work than necessary (since redisplay is called extremely often and is potentially a huge time sink), and depend heavily on notifications from the objects themselves that changes have occurred, so that redisplay doesn’t explicitly have to check each possible object. The redisplay mechanism also contains a great deal of caching to further speed things up; some of this caching is contained within the various displayable objects.

redisplay-output.c goes through the redisplay structures and converts them into calls to device-specific methods to actually output the screen changes.

redisplay-x.c and redisplay-tty.c are two implementations of these redisplay output methods, for X frames and TTY frames, respectively.

indent.c

This module contains various functions and Lisp primitives for converting between buffer positions and screen positions. These functions call the redisplay mechanism to do most of the work, and then examine the redisplay structures to get the necessary information. This module needs work.

termcap.c
terminfo.c
tparam.c

These files contain functions for working with the termcap (BSD-style) and terminfo (System V style) databases of terminal capabilities and escape sequences, used when SXEmacs is displaying in a TTY.

cm.c
cm.h

These files provide some miscellaneous TTY-output functions and should probably be merged into redisplay-tty.c.