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emacs/src/cm.c

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/* Cursor motion subroutines for GNU Emacs.
Copyright (C) 1985, 1995, 2001-2024 Free Software Foundation, Inc.
based primarily on public domain code written by Chris Torek
This file is part of GNU Emacs.
GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
#include "lisp.h"
#include "cm.h"
#include "sysstdio.h"
#include "termchar.h"
#include "tparam.h"
#define BIG 9999 /* Good on 32-bit hosts. */
int cost; /* sums up costs */
int
evalcost (int c)
{
cost++;
return c;
}
/* The terminal to use for low-level output. */
struct tty_display_info *current_tty;
int
cmputc (int c)
{
if (current_tty->termscript)
putc (c & 0177, current_tty->termscript);
putc (c & 0177, current_tty->output);
return c;
}
/* NEXT TWO ARE DONE WITH MACROS */
#if 0
/*
* Assume the cursor is at row row, column col. Normally used only after
* clearing the screen, when the cursor is at (0, 0), but what the heck,
* let's let the guy put it anywhere.
*/
static
at (tty, row, col) {
curY (tty) = row;
curX (tty) = col;
}
/*
* Add n columns to the current cursor position.
*/
static
addcol (tty, n) {
curX (tty) += n;
/*
* If cursor hit edge of screen, what happened?
* N.B.: DO NOT!! write past edge of screen. If you do, you
* deserve what you get. Furthermore, on terminals with
* autowrap (but not magicwrap), don't write in the last column
* of the last line.
*/
if (curX (tty) == tty->Wcm->cm_cols) {
/*
* Well, if magicwrap, still there, past the edge of the
* screen (!). If autowrap, on the col 0 of the next line.
* Otherwise on last column.
*/
if (tty->Wcm->cm_magicwrap)
; /* "limbo" */
else if (tty->Wcm->cm_autowrap) {
curX (tty) = 0;
curY (tty) ++; /* Beware end of screen! */
}
else
curX (tty)--;
}
}
#endif
/*
* Terminals with magicwrap (xn) don't all behave identically.
* The VT100 leaves the cursor in the last column but will wrap before
* printing the next character. I hear that the Concept terminal does
* the wrap immediately but ignores the next newline it sees. And some
* terminals just have buggy firmware, and think that the cursor is still
* in limbo if we use direct cursor addressing from the phantom column.
* The only guaranteed safe thing to do is to emit a CRLF immediately
* after we reach the last column; this takes us to a known state.
*/
void
cmcheckmagic (struct tty_display_info *tty)
{
if (curX (tty) == FrameCols (tty))
{
if (!MagicWrap (tty) || curY (tty) >= FrameRows (tty) - 1)
emacs_abort ();
if (tty->termscript)
putc ('\r', tty->termscript);
putc ('\r', tty->output);
if (tty->termscript)
putc ('\n', tty->termscript);
putc ('\n', tty->output);
curX (tty) = 0;
curY (tty)++;
}
}
/*
* (Re)Initialize the cost factors, given the output speed of the terminal
* in the variable ospeed. (Note: this holds B300, B9600, etc -- ie stuff
* out of <sgtty.h>.)
*/
void
cmcostinit (struct tty_display_info *tty)
{
char *p;
#define COST(x,e) (x ? (cost = 0, tputs (x, 1, e), cost) : BIG)
#define CMCOST(x,e) ((x == 0) ? BIG : (p = tgoto(x, 0, 0), COST(p ,e)))
tty->Wcm->cc_up = COST (tty->Wcm->cm_up, evalcost);
tty->Wcm->cc_down = COST (tty->Wcm->cm_down, evalcost);
tty->Wcm->cc_left = COST (tty->Wcm->cm_left, evalcost);
tty->Wcm->cc_right = COST (tty->Wcm->cm_right, evalcost);
tty->Wcm->cc_home = COST (tty->Wcm->cm_home, evalcost);
tty->Wcm->cc_cr = COST (tty->Wcm->cm_cr, evalcost);
tty->Wcm->cc_ll = COST (tty->Wcm->cm_ll, evalcost);
tty->Wcm->cc_tab = tty->Wcm->cm_tabwidth ? COST (tty->Wcm->cm_tab, evalcost) : BIG;
/*
* These last three are actually minimum costs. When (if) they are
* candidates for the least-cost motion, the real cost is computed.
* (Note that "0" is the assumed to generate the minimum cost.
* While this is not necessarily true, I have yet to see a terminal
* for which is not; all the terminals that have variable-cost
* cursor motion seem to take straight numeric values. --ACT)
*/
tty->Wcm->cc_abs = CMCOST (tty->Wcm->cm_abs, evalcost);
tty->Wcm->cc_habs = CMCOST (tty->Wcm->cm_habs, evalcost);
tty->Wcm->cc_vabs = CMCOST (tty->Wcm->cm_vabs, evalcost);
#undef CMCOST
#undef COST
}
/*
* Calculate the cost to move from (srcy, srcx) to (dsty, dstx) using
* up and down, and left and right, motions, and tabs. If doit is set
* actually perform the motion.
*/
static int
calccost (struct tty_display_info *tty,
int srcy, int srcx, int dsty, int dstx, int doit)
{
register int deltay,
deltax,
c,
totalcost;
int ntabs,
n2tabs,
tabx,
tab2x,
tabcost;
register const char *p;
/* If have just wrapped on a terminal with xn,
don't believe the cursor position: give up here
and force use of absolute positioning. */
if (curX (tty) == tty->Wcm->cm_cols)
goto fail;
totalcost = 0;
if ((deltay = dsty - srcy) == 0)
goto x;
if (deltay < 0)
p = tty->Wcm->cm_up, c = tty->Wcm->cc_up, deltay = -deltay;
else
p = tty->Wcm->cm_down, c = tty->Wcm->cc_down;
if (c == BIG) { /* caint get thar from here */
if (doit)
fputs ("OOPS", stdout);
return c;
}
totalcost = c * deltay;
if (doit)
do
emacs_tputs (tty, p, 1, cmputc);
while (--deltay > 0);
x:
if ((deltax = dstx - srcx) == 0)
goto done;
if (deltax < 0) {
p = tty->Wcm->cm_left, c = tty->Wcm->cc_left, deltax = -deltax;
goto dodelta; /* skip all the tab junk */
}
/* Tabs (the toughie) */
if (tty->Wcm->cc_tab >= BIG || !tty->Wcm->cm_usetabs)
goto olddelta; /* forget it! */
/*
* ntabs is # tabs towards but not past dstx; n2tabs is one more
* (ie past dstx), but this is only valid if that is not past the
* right edge of the screen. We can check that at the same time
* as we figure out where we would be if we use the tabs (which
* we will put into tabx (for ntabs) and tab2x (for n2tabs)).
*/
ntabs = (deltax + srcx % tty->Wcm->cm_tabwidth) / tty->Wcm->cm_tabwidth;
n2tabs = ntabs + 1;
tabx = (srcx / tty->Wcm->cm_tabwidth + ntabs) * tty->Wcm->cm_tabwidth;
tab2x = tabx + tty->Wcm->cm_tabwidth;
if (tab2x >= tty->Wcm->cm_cols) /* too far (past edge) */
n2tabs = 0;
/*
* Now set tabcost to the cost for using ntabs, and c to the cost
* for using n2tabs, then pick the minimum.
*/
/* cost for ntabs + cost for right motion */
tabcost = ntabs ? ntabs * tty->Wcm->cc_tab + (dstx - tabx) * tty->Wcm->cc_right
: BIG;
/* cost for n2tabs + cost for left motion */
c = n2tabs ? n2tabs * tty->Wcm->cc_tab + (tab2x - dstx) * tty->Wcm->cc_left
: BIG;
if (c < tabcost) /* then cheaper to overshoot & back up */
ntabs = n2tabs, tabcost = c, tabx = tab2x;
if (tabcost >= BIG) /* caint use tabs */
goto newdelta;
/*
* See if tabcost is less than just moving right
*/
if (tabcost < (deltax * tty->Wcm->cc_right)) {
totalcost += tabcost; /* use the tabs */
if (doit)
while (--ntabs >= 0)
emacs_tputs (tty, tty->Wcm->cm_tab, 1, cmputc);
srcx = tabx;
}
/*
* Now might as well just recompute the delta.
*/
newdelta:
if ((deltax = dstx - srcx) == 0)
goto done;
olddelta:
if (deltax > 0)
p = tty->Wcm->cm_right, c = tty->Wcm->cc_right;
else
p = tty->Wcm->cm_left, c = tty->Wcm->cc_left, deltax = -deltax;
dodelta:
if (c == BIG) { /* caint get thar from here */
fail:
if (doit)
fputs ("OOPS", stdout);
return BIG;
}
totalcost += c * deltax;
if (doit)
do
emacs_tputs (tty, p, 1, cmputc);
while (--deltax > 0);
done:
return totalcost;
}
#if 0
void
losecursor (void)
{
curY = -1;
}
#endif
#define USEREL 0
#define USEHOME 1
#define USELL 2
#define USECR 3
void
cmgoto (struct tty_display_info *tty, int row, int col)
{
int homecost,
crcost,
llcost,
relcost,
directcost;
int use UNINIT;
char *p;
const char *dcm;
/* First the degenerate case */
if (row == curY (tty) && col == curX (tty)) /* already there */
return;
if (curY (tty) >= 0 && curX (tty) >= 0)
{
/* We may have quick ways to go to the upper-left, bottom-left,
* start-of-line, or start-of-next-line. Or it might be best to
* start where we are. Examine the options, and pick the cheapest.
*/
relcost = calccost (tty, curY (tty), curX (tty), row, col, 0);
use = USEREL;
if ((homecost = tty->Wcm->cc_home) < BIG)
homecost += calccost (tty, 0, 0, row, col, 0);
if (homecost < relcost)
relcost = homecost, use = USEHOME;
if ((llcost = tty->Wcm->cc_ll) < BIG)
llcost += calccost (tty, tty->Wcm->cm_rows - 1, 0, row, col, 0);
if (llcost < relcost)
relcost = llcost, use = USELL;
if ((crcost = tty->Wcm->cc_cr) < BIG) {
if (tty->Wcm->cm_autolf)
if (curY (tty) + 1 >= tty->Wcm->cm_rows)
crcost = BIG;
else
crcost += calccost (tty, curY (tty) + 1, 0, row, col, 0);
else
crcost += calccost (tty, curY (tty), 0, row, col, 0);
}
if (crcost < relcost)
relcost = crcost, use = USECR;
directcost = tty->Wcm->cc_abs, dcm = tty->Wcm->cm_abs;
if (row == curY (tty) && tty->Wcm->cc_habs < BIG)
directcost = tty->Wcm->cc_habs, dcm = tty->Wcm->cm_habs;
else if (col == curX (tty) && tty->Wcm->cc_vabs < BIG)
directcost = tty->Wcm->cc_vabs, dcm = tty->Wcm->cm_vabs;
}
else
{
directcost = 0, relcost = 100000;
dcm = tty->Wcm->cm_abs;
}
/*
* In the following comparison, the = in <= is because when the costs
* are the same, it looks nicer (I think) to move directly there.
*/
if (directcost <= relcost)
{
/* compute REAL direct cost */
cost = 0;
p = (dcm == tty->Wcm->cm_habs
? tgoto (dcm, row, col)
: tgoto (dcm, col, row));
emacs_tputs (tty, p, 1, evalcost);
if (cost <= relcost)
{ /* really is cheaper */
emacs_tputs (tty, p, 1, cmputc);
curY (tty) = row, curX (tty) = col;
return;
}
}
switch (use)
{
case USEHOME:
emacs_tputs (tty, tty->Wcm->cm_home, 1, cmputc);
curY (tty) = 0, curX (tty) = 0;
break;
case USELL:
emacs_tputs (tty, tty->Wcm->cm_ll, 1, cmputc);
curY (tty) = tty->Wcm->cm_rows - 1, curX (tty) = 0;
break;
case USECR:
emacs_tputs (tty, tty->Wcm->cm_cr, 1, cmputc);
if (tty->Wcm->cm_autolf)
curY (tty)++;
curX (tty) = 0;
break;
}
(void) calccost (tty, curY (tty), curX (tty), row, col, 1);
curY (tty) = row, curX (tty) = col;
}
/* Clear out all terminal info.
Used before copying into it the info on the actual terminal.
*/
void
Wcm_clear (struct tty_display_info *tty)
{
memset (tty->Wcm, 0, sizeof (struct cm));
UP = 0;
BC = 0;
}
/*
* Initialized stuff
* Return 0 if can do CM.
* Return -1 if cannot.
* Return -2 if size not specified.
*/
int
Wcm_init (struct tty_display_info *tty)
{
#if 0
if (tty->Wcm->cm_abs && !tty->Wcm->cm_ds)
return 0;
#endif
if (tty->Wcm->cm_abs)
return 0;
/* Require up and left, and, if no absolute, down and right */
if (!tty->Wcm->cm_up || !tty->Wcm->cm_left)
return - 1;
if (!tty->Wcm->cm_abs && (!tty->Wcm->cm_down || !tty->Wcm->cm_right))
return - 1;
/* Check that we know the size of the screen.... */
if (tty->Wcm->cm_rows <= 0 || tty->Wcm->cm_cols <= 0)
return - 2;
return 0;
}
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