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diff --git a/contrib/ncurses/misc/hackguide.html b/contrib/ncurses/misc/hackguide.html deleted file mode 100644 index 417399a68365..000000000000 --- a/contrib/ncurses/misc/hackguide.html +++ /dev/null @@ -1,883 +0,0 @@ -<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 3.0//EN"> -<!-- - $Id: hackguide.html,v 1.23 1999/01/17 00:15:48 tom Exp $ ---> -<HTML> -<HEAD> -<TITLE>A Hacker's Guide to Ncurses Internals</TITLE> -<link rev="made" href="mailto:bugs-ncurses@gnu.org"> -<!-- -This document is self-contained, *except* that there is one relative link to -the ncurses-intro.html document, expected to be in the same directory with -this one. ---> -</HEAD> -<BODY> - -<H1>A Hacker's Guide to NCURSES</H1> - -<H1>Contents</H1> -<UL> -<LI><A HREF="#abstract">Abstract</A> -<P> -<LI><A HREF="#objective">Objective of the Package</A> -<UL> -<LI><A HREF="#whysvr4">Why System V Curses?</A> -<LI><A HREF="#extensions">How to Design Extensions</A> -</UL> -<LI><A HREF="#portability">Portability and Configuration</A><UL> -</UL> -<LI><A HREF="#documentation">Documentation Conventions</A> -<P> -<LI><A HREF="#bugtrack">How to Report Bugs</A> -<P> -<LI><A HREF="#ncurslib">A Tour of the Ncurses Library</A> -<UL> -<LI><A HREF="#loverview">Library Overview</A> -<LI><A HREF="#engine">The Engine Room</A> -<LI><A HREF="#input">Keyboard Input</A> -<LI><A HREF="#mouse">Mouse Events</A> -<LI><A HREF="#output">Output and Screen Updating</A> -</UL> -<LI><A HREF="#fmnote">The Forms and Menu Libraries</A> -<P> -<LI><A HREF="#tic">A Tour of the Terminfo Compiler</A> -<UL> -<LI><A HREF="#nonuse">Translation of Non-<STRONG>use</STRONG> Capabilities</A> -<LI><A HREF="#uses">Use Capability Resolution</A> -<LI><A HREF="#translation">Source-Form Translation</A> -</UL> -<LI><A HREF="#utils">Other Utilities</A> -<P> -<LI><A HREF="#style">Style Tips for Developers</A> -<P> -<LI><A HREF="#port">Porting Hints</A> -</UL> - -<H1><A NAME="abstract">Abstract</A></H1> - -This document is a hacker's tour of the <STRONG>ncurses</STRONG> library and utilities. -It discusses design philosophy, implementation methods, and the -conventions used for coding and documentation. It is recommended -reading for anyone who is interested in porting, extending or improving the -package. <P> - -<H1><A NAME="objective">Objective of the Package</A></H1> - -The objective of the <STRONG>ncurses</STRONG> package is to provide a free software API for -character-cell terminals and terminal emulators with the following -characteristics: <P> - -<UL> -<LI>Source-compatible with historical curses implementations (including - the original BSD curses and System V curses. -<P> -<LI>Conformant with the XSI Curses standard issued as part of XPG4 by - X/Open. -<P> -<LI>High-quality -- stable and reliable code, wide portability, good - packaging, superior documentation. -<P> -<LI>Featureful -- should eliminate as much of the drudgery of C interface - programming as possible, freeing programmers to think at a higher - level of design. -</UL> - -These objectives are in priority order. So, for example, source -compatibility with older version must trump featurefulness -- we cannot -add features if it means breaking the portion of the API corresponding -to historical curses versions. <P> - -<H2><A NAME="whysvr4">Why System V Curses?</A></H2> - -We used System V curses as a model, reverse-engineering their API, in -order to fulfill the first two objectives. <P> - -System V curses implementations can support BSD curses programs with -just a recompilation, so by capturing the System V API we also -capture BSD's. <P> - -More importantly for the future, the XSI Curses standard issued by X/Open -is explicitly and closely modeled on System V. So conformance with -System V took us most of the way to base-level XSI conformance. <P> - -<H2><A NAME="extensions">How to Design Extensions</A></H2> - -The third objective (standards conformance) requires that it be easy to -condition source code using <STRONG>ncurses</STRONG> so that the absence of nonstandard -extensions does not break the code. <P> - -Accordingly, we have a policy of associating with each nonstandard extension -a feature macro, so that ncurses client code can use this macro to condition -in or out the code that requires the <STRONG>ncurses</STRONG> extension. <P> - -For example, there is a macro <CODE>NCURSES_MOUSE_VERSION</CODE> which XSI Curses -does not define, but which is defined in the <STRONG>ncurses</STRONG> library header. -You can use this to condition the calls to the mouse API calls. <P> - -<H1><A NAME="portability">Portability and Configuration</A></H1> - -Code written for <STRONG>ncurses</STRONG> may assume an ANSI-standard C compiler and -POSIX-compatible OS interface. It may also assume the presence of a -System-V-compatible <EM>select(2)</EM> call. <P> - -We encourage (but do not require) developers to make the code friendly -to less-capable UNIX environments wherever possible. <P> - -We encourage developers to support OS-specific optimizations and methods -not available under POSIX/ANSI, provided only that: <P> - -<UL> -<LI>All such code is properly conditioned so the build process does not - attempt to compile it under a plain ANSI/POSIX environment. -<P> -<LI>Adding such implementation methods does not introduce incompatibilities - in the <STRONG>ncurses</STRONG> API between platforms. -</UL> - -We use GNU <CODE>autoconf(1)</CODE> as a tool to deal with portability issues. -The right way to leverage an OS-specific feature is to modify the autoconf -specification files (configure.in and aclocal.m4) to set up a new feature -macro, which you then use to condition your code. <P> - -<H1><A NAME="documentation">Documentation Conventions</A></H1> - -There are three kinds of documentation associated with this package. Each -has a different preferred format: <P> - -<UL> -<LI>Package-internal files (README, INSTALL, TO-DO etc.) -<LI>Manual pages. -<LI>Everything else (i.e., narrative documentation). -</UL> - -Our conventions are simple: <P> -<OL> -<LI><STRONG>Maintain package-internal files in plain text.</STRONG> - The expected viewer for them <EM>more(1)</EM> or an editor window; there's - no point in elaborate mark-up. <P> - -<LI><STRONG>Mark up manual pages in the man macros.</STRONG> These have to be viewable - through traditional <EM>man(1)</EM> programs. <P> - -<LI><STRONG>Write everything else in HTML.</STRONG> -</OL> - -When in doubt, HTMLize a master and use <EM>lynx(1)</EM> to generate -plain ASCII (as we do for the announcement document). <P> - -The reason for choosing HTML is that it's (a) well-adapted for on-line -browsing through viewers that are everywhere; (b) more easily readable -as plain text than most other mark-ups, if you don't have a viewer; and (c) -carries enough information that you can generate a nice-looking printed -version from it. Also, of course, it make exporting things like the -announcement document to WWW pretty trivial.<P> - -<H1><A NAME="bugtrack">How to Report Bugs</A></H1> - -The <A NAME="bugreport">reporting address for bugs</A> is -<A HREF="mailto:bug-ncurses@gnu.org">bug-ncurses@gnu.org</A>. -This is a majordomo list; to join, write -to <CODE>bug-ncurses-request@gnu.org</CODE> with a message containing the line: -<PRE> - subscribe <name>@<host.domain> -</PRE> - -The <CODE>ncurses</CODE> code is maintained by a small group of -volunteers. While we try our best to fix bugs promptly, we simply -don't have a lot of hours to spend on elementary hand-holding. We rely -on intelligent cooperation from our users. If you think you have -found a bug in <CODE>ncurses</CODE>, there are some steps you can take -before contacting us that will help get the bug fixed quickly. <P> - -In order to use our bug-fixing time efficiently, we put people who -show us they've taken these steps at the head of our queue. This -means that if you don't, you'll probably end up at the tail end and -have to wait a while. <P> - -<OL> -<LI>Develop a recipe to reproduce the bug. <P> - -Bugs we can reproduce are likely to be fixed very quickly, often -within days. The most effective single thing you can do to get a -quick fix is develop a way we can duplicate the bad behavior -- -ideally, by giving us source for a small, portable test program that -breaks the library. (Even better is a keystroke recipe using one of -the test programs provided with the distribution.) <P> - -<LI>Try to reproduce the bug on a different terminal type. <P> - -In our experience, most of the behaviors people report as library bugs -are actually due to subtle problems in terminal descriptions. This is -especially likely to be true if you're using a traditional -asynchronous terminal or PC-based terminal emulator, rather than xterm -or a UNIX console entry. <P> - -It's therefore extremely helpful if you can tell us whether or not your -problem reproduces on other terminal types. Usually you'll have both -a console type and xterm available; please tell us whether or not your -bug reproduces on both. <P> - -If you have xterm available, it is also good to collect xterm reports for -different window sizes. This is especially true if you normally use an -unusual xterm window size -- a surprising number of the bugs we've seen -are either triggered or masked by these. <P> - -<LI>Generate and examine a trace file for the broken behavior. <P> - -Recompile your program with the debugging versions of the libraries. -Insert a <CODE>trace()</CODE> call with the argument set to <CODE>TRACE_UPDATE</CODE>. -(See <A HREF="ncurses-intro.html#debugging">"Writing Programs with -NCURSES"</A> for details on trace levels.) -Reproduce your bug, then look at the trace file to see what the library -was actually doing. <P> - -Another frequent cause of apparent bugs is application coding errors -that cause the wrong things to be put on the virtual screen. Looking -at the virtual-screen dumps in the trace file will tell you immediately if -this is happening, and save you from the possible embarrassment of being -told that the bug is in your code and is your problem rather than ours. <P> - -If the virtual-screen dumps look correct but the bug persists, it's -possible to crank up the trace level to give more and more information -about the library's update actions and the control sequences it issues -to perform them. The test directory of the distribution contains a -tool for digesting these logs to make them less tedious to wade -through. <P> - -Often you'll find terminfo problems at this stage by noticing that the -escape sequences put out for various capabilities are wrong. If not, -you're likely to learn enough to be able to characterize any bug in -the screen-update logic quite exactly. <P> - -<LI>Report details and symptoms, not just interpretations. <P> - -If you do the preceding two steps, it is very likely that you'll discover -the nature of the problem yourself and be able to send us a fix. This -will create happy feelings all around and earn you good karma for the first -time you run into a bug you really can't characterize and fix yourself. <P> - -If you're still stuck, at least you'll know what to tell us. Remember, we -need details. If you guess about what is safe to leave out, you are too -likely to be wrong. <P> - -If your bug produces a bad update, include a trace file. Try to make -the trace at the <EM>least</EM> voluminous level that pins down the -bug. Logs that have been through tracemunch are OK, it doesn't throw -away any information (actually they're better than un-munched ones because -they're easier to read). <P> - -If your bug produces a core-dump, please include a symbolic stack trace -generated by gdb(1) or your local equivalent. <P> - -Tell us about every terminal on which you've reproduced the bug -- and -every terminal on which you can't. Ideally, sent us terminfo sources -for all of these (yours might differ from ours). <P> - -Include your ncurses version and your OS/machine type, of course! You can -find your ncurses version in the <CODE>curses.h</CODE> file. -</OL> - -If your problem smells like a logic error or in cursor movement or -scrolling or a bad capability, there are a couple of tiny test frames -for the library algorithms in the progs directory that may help you -isolate it. These are not part of the normal build, but do have their -own make productions. <P> - -The most important of these is <CODE>mvcur</CODE>, a test frame for the -cursor-movement optimization code. With this program, you can see -directly what control sequences will be emitted for any given cursor -movement or scroll/insert/delete operations. If you think you've got -a bad capability identified, you can disable it and test again. The -program is command-driven and has on-line help. <P> - -If you think the vertical-scroll optimization is broken, or just want to -understand how it works better, build <CODE>hashmap</CODE> and read the -header comments of <CODE>hardscroll.c</CODE> and <CODE>hashmap.c</CODE>; then try -it out. You can also test the hardware-scrolling optimization separately -with <CODE>hardscroll</CODE>. <P> - -There's one other interactive tester, <CODE>tctest</CODE>, that exercises -translation between termcap and terminfo formats. If you have a serious -need to run this, you probably belong on our development team! <P> - -<H1><A NAME="ncurslib">A Tour of the Ncurses Library</A></H1> - -<H2><A NAME="loverview">Library Overview</A></H2> - -Most of the library is superstructure -- fairly trivial convenience -interfaces to a small set of basic functions and data structures used -to manipulate the virtual screen (in particular, none of this code -does any I/O except through calls to more fundamental modules -described below). The files -<blockquote> -<CODE> -lib_addch.c -lib_bkgd.c -lib_box.c -lib_chgat.c -lib_clear.c -lib_clearok.c -lib_clrbot.c -lib_clreol.c -lib_colorset.c -lib_data.c -lib_delch.c -lib_delwin.c -lib_echo.c -lib_erase.c -lib_gen.c -lib_getstr.c -lib_hline.c -lib_immedok.c -lib_inchstr.c -lib_insch.c -lib_insdel.c -lib_insstr.c -lib_instr.c -lib_isendwin.c -lib_keyname.c -lib_leaveok.c -lib_move.c -lib_mvwin.c -lib_overlay.c -lib_pad.c -lib_printw.c -lib_redrawln.c -lib_scanw.c -lib_screen.c -lib_scroll.c -lib_scrollok.c -lib_scrreg.c -lib_set_term.c -lib_slk.c -lib_slkatr_set.c -lib_slkatrof.c -lib_slkatron.c -lib_slkatrset.c -lib_slkattr.c -lib_slkclear.c -lib_slkcolor.c -lib_slkinit.c -lib_slklab.c -lib_slkrefr.c -lib_slkset.c -lib_slktouch.c -lib_touch.c -lib_unctrl.c -lib_vline.c -lib_wattroff.c -lib_wattron.c -lib_window.c -</CODE> -</blockquote> -are all in this category. They are very -unlikely to need change, barring bugs or some fundamental -reorganization in the underlying data structures. <P> - -These files are used only for debugging support: -<blockquote><code> -lib_trace.c -lib_traceatr.c -lib_tracebits.c -lib_tracechr.c -lib_tracedmp.c -lib_tracemse.c -trace_buf.c -</blockquote></code> -It is rather unlikely you will ever need to change these, unless -you want to introduce a new debug trace level for some reasoon.<P> - -There is another group of files that do direct I/O via <EM>tputs()</EM>, -computations on the terminal capabilities, or queries to the OS -environment, but nevertheless have only fairly low complexity. These -include: -<blockquote><code> -lib_acs.c -lib_beep.c -lib_color.c -lib_endwin.c -lib_initscr.c -lib_longname.c -lib_newterm.c -lib_options.c -lib_termcap.c -lib_ti.c -lib_tparm.c -lib_tputs.c -lib_vidattr.c -read_entry.c. -</blockquote></code> -They are likely to need revision only if -ncurses is being ported to an environment without an underlying -terminfo capability representation. <P> - -These files -have serious hooks into -the tty driver and signal facilities: -<blockquote><code> -lib_kernel.c -lib_baudrate.c -lib_raw.c -lib_tstp.c -lib_twait.c -</blockquote></code> -If you run into porting snafus -moving the package to another UNIX, the problem is likely to be in one -of these files. -The file <CODE>lib_print.c</CODE> uses sleep(2) and also -falls in this category.<P> - -Almost all of the real work is done in the files -<blockquote><code> -hardscroll.c -hashmap.c -lib_addch.c -lib_doupdate.c -lib_getch.c -lib_mouse.c -lib_mvcur.c -lib_refresh.c -lib_setup.c -lib_vidattr.c -</blockquote></code> -Most of the algorithmic complexity in the -library lives in these files. -If there is a real bug in <STRONG>ncurses</STRONG> itself, it's probably here. -We'll tour some of these files in detail -below (see <A HREF="#engine">The Engine Room</A>). <P> - -Finally, there is a group of files that is actually most of the -terminfo compiler. The reason this code lives in the <STRONG>ncurses</STRONG> -library is to support fallback to /etc/termcap. These files include -<blockquote><code> -alloc_entry.c -captoinfo.c -comp_captab.c -comp_error.c -comp_hash.c -comp_parse.c -comp_scan.c -parse_entry.c -read_termcap.c -write_entry.c -</blockquote></code> -We'll discuss these in the compiler tour. <P> - -<H2><A NAME="engine">The Engine Room</A></H2> - -<H3><A NAME="input">Keyboard Input</A></H3> - -All <CODE>ncurses</CODE> input funnels through the function -<CODE>wgetch()</CODE>, defined in <CODE>lib_getch.c</CODE>. This function is -tricky; it has to poll for keyboard and mouse events and do a running -match of incoming input against the set of defined special keys. <P> - -The central data structure in this module is a FIFO queue, used to -match multiple-character input sequences against special-key -capabilities; also to implement pushback via <CODE>ungetch()</CODE>. <P> - -The <CODE>wgetch()</CODE> code distinguishes between function key -sequences and the same sequences typed manually by doing a timed wait -after each input character that could lead a function key sequence. -If the entire sequence takes less than 1 second, it is assumed to have -been generated by a function key press. <P> - -Hackers bruised by previous encounters with variant <CODE>select(2)</CODE> -calls may find the code in <CODE>lib_twait.c</CODE> interesting. It deals -with the problem that some BSD selects don't return a reliable -time-left value. The function <CODE>timed_wait()</CODE> effectively -simulates a System V select. <P> - -<H3><A NAME="mouse">Mouse Events</A></H3> - -If the mouse interface is active, <CODE>wgetch()</CODE> polls for mouse -events each call, before it goes to the keyboard for input. It is -up to <CODE>lib_mouse.c</CODE> how the polling is accomplished; it may vary -for different devices. <P> - -Under xterm, however, mouse event notifications come in via the keyboard -input stream. They are recognized by having the <STRONG>kmous</STRONG> capability -as a prefix. This is kind of klugey, but trying to wire in recognition of -a mouse key prefix without going through the function-key machinery would -be just too painful, and this turns out to imply having the prefix somewhere -in the function-key capabilities at terminal-type initialization. <P> - -This kluge only works because <STRONG>kmous</STRONG> isn't actually used by any -historic terminal type or curses implementation we know of. Best -guess is it's a relic of some forgotten experiment in-house at Bell -Labs that didn't leave any traces in the publicly-distributed System V -terminfo files. If System V or XPG4 ever gets serious about using it -again, this kluge may have to change. <P> - -Here are some more details about mouse event handling: <P> - -The <CODE>lib_mouse()</CODE>code is logically split into a lower level that -accepts event reports in a device-dependent format and an upper level that -parses mouse gestures and filters events. The mediating data structure is a -circular queue of event structures. <P> - -Functionally, the lower level's job is to pick up primitive events and -put them on the circular queue. This can happen in one of two ways: -either (a) <CODE>_nc_mouse_event()</CODE> detects a series of incoming -mouse reports and queues them, or (b) code in <CODE>lib_getch.c</CODE> detects the -<STRONG>kmous</STRONG> prefix in the keyboard input stream and calls _nc_mouse_inline -to queue up a series of adjacent mouse reports. <P> - -In either case, <CODE>_nc_mouse_parse()</CODE> should be called after the -series is accepted to parse the digested mouse reports (low-level -events) into a gesture (a high-level or composite event). <P> - -<H3><A NAME="output">Output and Screen Updating</A></H3> - -With the single exception of character echoes during a <CODE>wgetnstr()</CODE> -call (which simulates cooked-mode line editing in an ncurses window), -the library normally does all its output at refresh time. <P> - -The main job is to go from the current state of the screen (as represented -in the <CODE>curscr</CODE> window structure) to the desired new state (as -represented in the <CODE>newscr</CODE> window structure), while doing as -little I/O as possible. <P> - -The brains of this operation are the modules <CODE>hashmap.c</CODE>, -<CODE>hardscroll.c</CODE> and <CODE>lib_doupdate.c</CODE>; the latter two use -<CODE>lib_mvcur.c</CODE>. Essentially, what happens looks like this: <P> - -The <CODE>hashmap.c</CODE> module tries to detect vertical motion -changes between the real and virtual screens. This information -is represented by the oldindex members in the newscr structure. -These are modified by vertical-motion and clear operations, and both are -re-initialized after each update. To this change-journalling -information, the hashmap code adds deductions made using a modified Heckel -algorithm on hash values generated from the line contents. <P> - -The <CODE>hardscroll.c</CODE> module computes an optimum set of scroll, -insertion, and deletion operations to make the indices match. It calls -<CODE>_nc_mvcur_scrolln()</CODE> in <CODE>lib_mvcur.c</CODE> to do those motions. <P> - -Then <CODE>lib_doupdate.c</CODE> goes to work. Its job is to do line-by-line -transformations of <CODE>curscr</CODE> lines to <CODE>newscr</CODE> lines. Its main -tool is the routine <CODE>mvcur()</CODE> in <CODE>lib_mvcur.c</CODE>. This routine -does cursor-movement optimization, attempting to get from given screen -location A to given location B in the fewest output characters posible. <P> - -If you want to work on screen optimizations, you should use the fact -that (in the trace-enabled version of the library) enabling the -<CODE>TRACE_TIMES</CODE> trace level causes a report to be emitted after -each screen update giving the elapsed time and a count of characters -emitted during the update. You can use this to tell when an update -optimization improves efficiency. <P> - -In the trace-enabled version of the library, it is also possible to disable -and re-enable various optimizations at runtime by tweaking the variable -<CODE>_nc_optimize_enable</CODE>. See the file <CODE>include/curses.h.in</CODE> -for mask values, near the end. <P> - -<H1><A NAME="fmnote">The Forms and Menu Libraries</A></H1> - -The forms and menu libraries should work reliably in any environment you -can port ncurses to. The only portability issue anywhere in them is what -flavor of regular expressions the built-in form field type TYPE_REGEXP -will recognize. <P> - -The configuration code prefers the POSIX regex facility, modeled on -System V's, but will settle for BSD regexps if the former isn't available. <P> - -Historical note: the panels code was written primarily to assist in -porting u386mon 2.0 (comp.sources.misc v14i001-4) to systems lacking -panels support; u386mon 2.10 and beyond use it. This version has been -slightly cleaned up for <CODE>ncurses</CODE>. <P> - -<H1><A NAME="tic">A Tour of the Terminfo Compiler</A></H1> - -The <STRONG>ncurses</STRONG> implementation of <STRONG>tic</STRONG> is rather complex -internally; it has to do a trying combination of missions. This starts -with the fact that, in addition to its normal duty of compiling -terminfo sources into loadable terminfo binaries, it has to be able to -handle termcap syntax and compile that too into terminfo entries. <P> - -The implementation therefore starts with a table-driven, dual-mode -lexical analyzer (in <CODE>comp_scan.c</CODE>). The lexer chooses its -mode (termcap or terminfo) based on the first `,' or `:' it finds in -each entry. The lexer does all the work of recognizing capability -names and values; the grammar above it is trivial, just "parse entries -till you run out of file". <P> - -<H2><A NAME="nonuse">Translation of Non-<STRONG>use</STRONG> Capabilities</A></H2> - -Translation of most things besides <STRONG>use</STRONG> capabilities is pretty -straightforward. The lexical analyzer's tokenizer hands each capability -name to a hash function, which drives a table lookup. The table entry -yields an index which is used to look up the token type in another table, -and controls interpretation of the value. <P> - -One possibly interesting aspect of the implementation is the way the -compiler tables are initialized. All the tables are generated by various -awk/sed/sh scripts from a master table <CODE>include/Caps</CODE>; these -scripts actually write C initializers which are linked to the compiler. -Furthermore, the hash table is generated in the same way, so it doesn't -have to be generated at compiler startup time (another benefit of this -organization is that the hash table can be in shareable text space). <P> - -Thus, adding a new capability is usually pretty trivial, just a matter -of adding one line to the <CODE>include/Caps</CODE> file. We'll have more -to say about this in the section on <A HREF="#translation">Source-Form -Translation</A>. <P> - -<H2><A NAME="uses">Use Capability Resolution</A></H2> - -The background problem that makes <STRONG>tic</STRONG> tricky isn't the capability -translation itself, it's the resolution of <STRONG>use</STRONG> capabilities. Older -versions would not handle forward <STRONG>use</STRONG> references for this reason -(that is, a using terminal always had to follow its use target in the -source file). By doing this, they got away with a simple implementation -tactic; compile everything as it blows by, then resolve uses from compiled -entries. <P> - -This won't do for <STRONG>ncurses</STRONG>. The problem is that that the whole -compilation process has to be embeddable in the <STRONG>ncurses</STRONG> library -so that it can be called by the startup code to translate termcap -entries on the fly. The embedded version can't go promiscuously writing -everything it translates out to disk -- for one thing, it will typically -be running with non-root permissions. <P> - -So our <STRONG>tic</STRONG> is designed to parse an entire terminfo file into a -doubly-linked circular list of entry structures in-core, and then do -<STRONG>use</STRONG> resolution in-memory before writing everything out. This -design has other advantages: it makes forward and back use-references -equally easy (so we get the latter for free), and it makes checking for -name collisions before they're written out easy to do. <P> - -And this is exactly how the embedded version works. But the stand-alone -user-accessible version of <STRONG>tic</STRONG> partly reverts to the historical -strategy; it writes to disk (not keeping in core) any entry with no -<STRONG>use</STRONG> references. <P> - -This is strictly a core-economy kluge, implemented because the -terminfo master file is large enough that some core-poor systems swap -like crazy when you compile it all in memory...there have been reports of -this process taking <STRONG>three hours</STRONG>, rather than the twenty seconds -or less typical on the author's development box. <P> - -So. The executable <STRONG>tic</STRONG> passes the entry-parser a hook that -<EM>immediately</EM> writes out the referenced entry if it has no use -capabilities. The compiler main loop refrains from adding the entry -to the in-core list when this hook fires. If some other entry later -needs to reference an entry that got written immediately, that's OK; -the resolution code will fetch it off disk when it can't find it in -core. <P> - -Name collisions will still be detected, just not as cleanly. The -<CODE>write_entry()</CODE> code complains before overwriting an entry that -postdates the time of <STRONG>tic</STRONG>'s first call to -<CODE>write_entry()</CODE>, Thus it will complain about overwriting -entries newly made during the <STRONG>tic</STRONG> run, but not about -overwriting ones that predate it. <P> - -<H2><A NAME="translation">Source-Form Translation</A></H2> - -Another use of <STRONG>tic</STRONG> is to do source translation between various termcap -and terminfo formats. There are more variants out there than you might -think; the ones we know about are described in the <STRONG>captoinfo(1)</STRONG> -manual page. <P> - -The translation output code (<CODE>dump_entry()</CODE> in -<CODE>ncurses/dump_entry.c</CODE>) is shared with the <STRONG>infocmp(1)</STRONG> -utility. It takes the same internal representation used to generate -the binary form and dumps it to standard output in a specified -format. <P> - -The <CODE>include/Caps</CODE> file has a header comment describing ways you -can specify source translations for nonstandard capabilities just by -altering the master table. It's possible to set up capability aliasing -or tell the compiler to plain ignore a given capability without writing -any C code at all. <P> - -For circumstances where you need to do algorithmic translation, there -are functions in <CODE>parse_entry.c</CODE> called after the parse of each -entry that are specifically intended to encapsulate such -translations. This, for example, is where the AIX <STRONG>box1</STRONG> capability -get translated to an <STRONG>acsc</STRONG> string.<P> - -<H1><A NAME="utils">Other Utilities</A></H1> - -The <STRONG>infocmp</STRONG> utility is just a wrapper around the same -entry-dumping code used by <STRONG>tic</STRONG> for source translation. Perhaps -the one interesting aspect of the code is the use of a predicate -function passed in to <CODE>dump_entry()</CODE> to control which -capabilities are dumped. This is necessary in order to handle both -the ordinary De-compilation case and entry difference reporting. <P> - -The <STRONG>tput</STRONG> and <STRONG>clear</STRONG> utilities just do an entry load -followed by a <CODE>tputs()</CODE> of a selected capability. <P> - -<H1><A NAME="style">Style Tips for Developers</A></H1> - -See the TO-DO file in the top-level directory of the source distribution -for additions that would be particularly useful. <P> - -The prefix <CODE>_nc_</CODE> should be used on library public functions that are -not part of the curses API in order to prevent pollution of the -application namespace. - -If you have to add to or modify the function prototypes in curses.h.in, -read ncurses/MKlib_gen.sh first so you can avoid breaking XSI conformance. - -Please join the ncurses mailing list. See the INSTALL file in the -top level of the distribution for details on the list. <P> - -Look for the string <CODE>FIXME</CODE> in source files to tag minor bugs -and potential problems that could use fixing. <P> - -Don't try to auto-detect OS features in the main body of the C code. -That's the job of the configuration system. <P> - -To hold down complexity, do make your code data-driven. Especially, -if you can drive logic from a table filtered out of -<CODE>include/Caps</CODE>, do it. If you find you need to augment the -data in that file in order to generate the proper table, that's still -preferable to ad-hoc code -- that's why the fifth field (flags) is -there. <P> - -Have fun! <P> - -<H1><A NAME="port">Porting Hints</A></H1> - -The following notes are intended to be a first step towards DOS and Macintosh -ports of the ncurses libraries. <P> - -The following library modules are `pure curses'; they operate only on -the curses internal structures, do all output through other curses -calls (not including <CODE>tputs()</CODE> and <CODE>putp()</CODE>) and do not -call any other UNIX routines such as signal(2) or the stdio library. -Thus, they should not need to be modified for single-terminal -ports. <P> - -<blockquote><code> -lib_addch.c -lib_addstr.c -lib_bkgd.c -lib_box.c -lib_clear.c -lib_clrbot.c -lib_clreol.c -lib_delch.c -lib_delwin.c -lib_erase.c -lib_inchstr.c -lib_insch.c -lib_insdel.c -lib_insstr.c -lib_keyname.c -lib_move.c -lib_mvwin.c -lib_newwin.c -lib_overlay.c -lib_pad.c -lib_printw.c -lib_refresh.c -lib_scanw.c -lib_scroll.c -lib_scrreg.c -lib_set_term.c -lib_touch.c -lib_tparm.c -lib_tputs.c -lib_unctrl.c -lib_window.c -panel.c -</blockquote></code> -<P> - -This module is pure curses, but calls outstr(): <P> - -<blockquote><code> -lib_getstr.c -</blockquote></code> -<P> - -These modules are pure curses, except that they use <CODE>tputs()</CODE> -and <CODE>putp()</CODE>: <P> - -<blockquote><code> -lib_beep.c -lib_color.c -lib_endwin.c -lib_options.c -lib_slk.c -lib_vidattr.c -</blockquote></code> -<P> - -This modules assist in POSIX emulation on non-POSIX systems: <P> -<DL> -<DT> sigaction.c -<DD> signal calls -</DL> - -The following source files will not be needed for a -single-terminal-type port. <P> - -<blockquote><code> -alloc_entry.c -captoinfo.c -clear.c -comp_captab.c -comp_error.c -comp_hash.c -comp_main.c -comp_parse.c -comp_scan.c -dump_entry.c -infocmp.c -parse_entry.c -read_entry.c -tput.c -write_entry.c -</blockquote></code> -<P> - -The following modules will use open()/read()/write()/close()/lseek() on files, -but no other OS calls. <P> - -<DL> -<DT>lib_screen.c -<DD>used to read/write screen dumps -<DT>lib_trace.c -<DD>used to write trace data to the logfile -</DL> - -Modules that would have to be modified for a port start here: <P> - -The following modules are `pure curses' but contain assumptions inappropriate -for a memory-mapped port. <P> - -<dl> -<dt>lib_longname.c<dd>assumes there may be multiple terminals -<dt>lib_acs.c<dd>assumes acs_map as a double indirection -<dt>lib_mvcur.c<dd>assumes cursor moves have variable cost -<dt>lib_termcap.c<dd>assumes there may be multiple terminals -<dt>lib_ti.c<dd>assumes there may be multiple terminals -</dl> - -The following modules use UNIX-specific calls: - -<dl> -<dt>lib_doupdate.c<dd>input checking -<dt>lib_getch.c<dd>read() -<dt>lib_initscr.c<dd>getenv() -<dt>lib_newterm.c -<dt>lib_baudrate.c -<dt>lib_kernel.c<dd>various tty-manipulation and system calls -<dt>lib_raw.c<dd>various tty-manipulation calls -<dt>lib_setup.c<dd>various tty-manipulation calls -<dt>lib_restart.c<dd>various tty-manipulation calls -<dt>lib_tstp.c<dd>signal-manipulation calls -<dt>lib_twait.c<dd>gettimeofday(), select(). -</dl> - -<HR> -<ADDRESS>Eric S. Raymond <esr@snark.thyrsus.com></ADDRESS> -(Note: This is <EM>not</EM> the <A HREF="#bugtrack">bug address</A>!) -</BODY> -</HTML> |