ncurses 6.0 - patch 20161112

[ncurses.git] / man / curs_termcap.3x

diff --git a/man/curs_termcap.3x b/man/curs_termcap.3x
index f8977bebca9c9c49abf6d346392de98acbff11b2..9b21505603b968b74af2ea357cd98d4129a06a9e 100644 (file)
--- a/man/curs_termcap.3x
+++ b/man/curs_termcap.3x
@@ -1,5 +1,5 @@
 .\"***************************************************************************
-.\" Copyright (c) 1998-2012,2013 Free Software Foundation, Inc.              *
+.\" Copyright (c) 1998-2015,2016 Free Software Foundation, Inc.              *
 .\"                                                                          *
 .\" Permission is hereby granted, free of charge, to any person obtaining a  *
 .\" copy of this software and associated documentation files (the            *
@@ -26,7 +26,7 @@
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"
-.\" $Id: curs_termcap.3x,v 1.30 2013/01/19 15:58:48 tom Exp $
+.\" $Id: curs_termcap.3x,v 1.32 2016/03/19 22:52:25 tom Exp $
 .TH curs_termcap 3X ""
 .de bP
 .IP \(bu 4
@@ -121,9 +121,24 @@ or \-1 if it is not available.
 The \fBtgetstr\fR routine returns the string entry for \fIid\fR,
 or zero if it is not available.
 Use \fBtputs\fR to output the returned string.
-The return value will also be copied to the buffer pointed to by \fIarea\fR,
+The \fIarea\fP parameter is used as follows:
+.RS 3
+.bP
+It is assumed to be the address of a pointer to a buffer managed by the
+calling application.
+.bP
+However, ncurses checks to ensure that \fBarea\fP is not NULL,
+and also that the resulting buffer pointer is not NULL.
+If either check fails, the \fIarea\fP parameter is ignored.
+.bP
+If the checks succeed, ncurses also copies the return value to
+the buffer pointed to by \fIarea\fR,
 and the \fIarea\fR value will be updated to point past the null ending
 this value.
+.bP
+The return value itself is an address in the terminal description which
+is loaded into memory.
+.RE
 .PP
 Only the first two characters of the \fBid\fR parameter of
 \fBtgetflag\fR,
@@ -131,8 +146,26 @@ Only the first two characters of the \fBid\fR parameter of
 \fBtgetstr\fR are compared in lookups.
 .SS FORMATTING CAPABILITIES
 .PP
-The \fBtgoto\fR routine instantiates the parameters into the given capability.
-The output from this routine is to be passed to \fBtputs\fR.
+The \fBtgoto\fR routine expands the given capability using the parameters.
+.bP
+Because the capability may have padding characters,
+the output of \fBtgoto\fP should be passed to \fBtputs\fR
+rather than some other output function such as \fBprintf\fP.
+.bP
+While \fBtgoto\fP is assumed to be used for the two-parameter
+cursor positioning capability,
+termcap applications also use it for single-parameter capabilities.
+.IP
+Doing this shows a quirk in \fBtgoto\fP: most hardware
+terminals use cursor addressing with \fIrow\fP first,
+but the original developers of the termcap interface chose to
+put the \fIcolumn\fP parameter first.
+The \fBtgoto\fP function swaps the order of parameters.
+It does this also for calls requiring only a single parameter.
+In that case, the first parameter is merely a placeholder.
+.bP
+Normally the ncurses library is compiled with terminfo support.
+In that case, \fBtgoto\fP uses \fBtparm\fP (a more capable formatter).
 .PP
 The \fBtputs\fR routine is described on the \fBcurs_terminfo\fR(3X) manual
 page.  It can retrieve capabilities by either termcap or terminfo name.