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basic.c
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C/C++ Source or Header
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1989-05-30
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9KB
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287 lines
/* basic.c */
/*
* The routines in this file move the cursor around on the screen. They
* compute a new value for the cursor, then adjust ".". The display code
* always updates the cursor location, so only moves between lines, or
* functions that adjust the top line in the window and invalidate the
* framing, are hard.
*/
#include <stdio.h>
#include "ed.h"
/*
* Move the cursor to the
* beginning of the current line.
* Trivial.
*/
gotobol(f, n)
{
curwp->w_doto = 0;
return (TRUE);
}
/*
* Move the cursor backwards by "n" characters. If "n" is less than zero call
* "forwchar" to actually do the move. Otherwise compute the new cursor
* location. Error if you try and move out of the buffer. Set the flag if the
* line pointer for dot changes.
*/
backchar(f, n)
register int n;
{
register LINE *lp;
if (n < 0)
return (forwchar(f, -n));
while (n--) {
if (curwp->w_doto == 0) {
if ((lp=lback(curwp->w_dotp)) == curbp->b_linep)
return (FALSE);
curwp->w_dotp = lp;
curwp->w_doto = llength(lp);
curwp->w_flag |= WFMOVE;
} else
curwp->w_doto--;
}
return (TRUE);
}
/*
* Move the cursor to the end of the current line. Trivial. No errors.
*/
gotoeol(f, n)
{
curwp->w_doto = llength(curwp->w_dotp);
return (TRUE);
}
/*
* Move the cursor forwwards by "n" characters. If "n" is less than zero call
* "backchar" to actually do the move. Otherwise compute the new cursor
* location, and move ".". Error if you try and move off the end of the
* buffer. Set the flag if the line pointer for dot changes.
*/
forwchar(f, n)
register int n;
{
if (n < 0)
return (backchar(f, -n));
while (n--) {
if (curwp->w_doto == llength(curwp->w_dotp)) {
if (curwp->w_dotp == curbp->b_linep)
return (FALSE);
curwp->w_dotp = lforw(curwp->w_dotp);
curwp->w_doto = 0;
curwp->w_flag |= WFMOVE;
} else
curwp->w_doto++;
}
return (TRUE);
}
/*
* Goto the beginning of the buffer. Massive adjustment of dot. This is
* considered to be hard motion; it really isn't if the original value of dot
* is the same as the new value of dot. Normally bound to "M-<".
*/
gotobob(f, n)
{
curwp->w_dotp = lforw(curbp->b_linep);
curwp->w_doto = 0;
curwp->w_flag |= WFHARD;
return (TRUE);
}
/*
* Move to the end of the buffer. Dot is always put at the end of the file
* (ZJ). The standard screen code does most of the hard parts of update.
* Bound to "M->".
*/
gotoeob(f, n)
{
curwp->w_dotp = curbp->b_linep;
curwp->w_doto = 0;
curwp->w_flag |= WFHARD;
return (TRUE);
}
/*
* Move forward by full lines. If the number of lines to move is less than
* zero, call the backward line function to actually do it. The last command
* controls how the goal column is set. Bound to "C-N". No errors are
* possible.
*/
forwline(f, n)
{
register LINE *dlp;
if (n < 0)
return (backline(f, -n));
if ((lastflag&CFCPCN) == 0) /* Reset goal if last */
curgoal = curcol; /* not C-P or C-N */
thisflag |= CFCPCN;
dlp = curwp->w_dotp;
while (n-- && dlp!=curbp->b_linep)
dlp = lforw(dlp);
curwp->w_dotp = dlp;
curwp->w_doto = getgoal(dlp);
curwp->w_flag |= WFMOVE;
return (TRUE);
}
/*
* This function is like "forwline", but goes backwards. The scheme is exactly
* the same. Check for arguments that are less than zero and call your
* alternate. Figure out the new line and call "movedot" to perform the
* motion. No errors are possible. Bound to "C-P".
*/
backline(f, n)
{
register LINE *dlp;
if (n < 0)
return (forwline(f, -n));
if ((lastflag&CFCPCN) == 0) /* Reset goal if the */
curgoal = curcol; /* last isn't C-P, C-N */
thisflag |= CFCPCN;
dlp = curwp->w_dotp;
while (n-- && lback(dlp)!=curbp->b_linep)
dlp = lback(dlp);
curwp->w_dotp = dlp;
curwp->w_doto = getgoal(dlp);
curwp->w_flag |= WFMOVE;
return (TRUE);
}
/*
* This routine, given a pointer to a LINE, and the current cursor goal
* column, return the best choice for the offset. The offset is returned.
* Used by "C-N" and "C-P".
*/
getgoal(dlp)
register LINE *dlp;
{
register int c;
register int col;
register int newcol;
register int dbo;
col = 0;
dbo = 0;
while (dbo != llength(dlp)) {
c = lgetc(dlp, dbo);
newcol = col;
if (c == '\t')
newcol |= 0x07;
else if (c<0x20 || c==0x7F)
++newcol;
++newcol;
if (newcol > curgoal)
break;
col = newcol;
++dbo;
}
return (dbo);
}
/*
* Scroll forward by a specified number of lines, or by a full page if no
* argument. Bound to "C-V". The "2" in the arithmetic on the window size is
* the overlap; this value is the default overlap value in ITS EMACS. Because
* this zaps the top line in the display window, we have to do a hard update.
*/
forwpage(f, n)
register int n;
{
register LINE *lp;
if (f == FALSE) {
n = curwp->w_ntrows - 2; /* Default scroll. */
if (n <= 0) /* Forget the overlap */
n = 1; /* if tiny window. */
} else if (n < 0)
return (backpage(f, -n));
#if CVMVAS
else /* Convert from pages */
n *= curwp->w_ntrows; /* to lines. */
#endif
lp = curwp->w_linep;
while (n-- && lp!=curbp->b_linep)
lp = lforw(lp);
curwp->w_linep = lp;
curwp->w_dotp = lp;
curwp->w_doto = 0;
curwp->w_flag |= WFHARD;
return (TRUE);
}
/*
* This command is like "forwpage", but it goes backwards. The "2", like
* above, is the overlap between the two windows. The value is from the ITS
* EMACS manual. Bound to "M-V". We do a hard update for exactly the same
* reason.
*/
backpage(f, n)
register int n;
{
register LINE *lp;
if (f == FALSE) {
n = curwp->w_ntrows - 2; /* Default scroll. */
if (n <= 0) /* Don't blow up if the */
n = 1; /* window is tiny. */
} else if (n < 0)
return (forwpage(f, -n));
#if CVMVAS
else /* Convert from pages */
n *= curwp->w_ntrows; /* to lines. */
#endif
lp = curwp->w_linep;
while (n-- && lback(lp)!=curbp->b_linep)
lp = lback(lp);
curwp->w_linep = lp;
curwp->w_dotp = lp;
curwp->w_doto = 0;
curwp->w_flag |= WFHARD;
return (TRUE);
}
/*
* Set the mark in the current window to the value of "." in the window. No
* errors are possible. Bound to "M-.".
*/
setmark(f, n)
{
curwp->w_markp = curwp->w_dotp;
curwp->w_marko = curwp->w_doto;
mlwrite("[Mark set]");
return (TRUE);
}
/*
* Swap the values of "." and "mark" in the current window. This is pretty
* easy, bacause all of the hard work gets done by the standard routine
* that moves the mark about. The only possible error is "no mark". Bound to
* "C-X C-X".
*/
swapmark(f, n)
{
register LINE *odotp;
register int odoto;
if (curwp->w_markp == NULL) {
mlwrite("No mark in this window");
return (FALSE);
}
odotp = curwp->w_dotp;
odoto = curwp->w_doto;
curwp->w_dotp = curwp->w_markp;
curwp->w_doto = curwp->w_marko;
curwp->w_markp = odotp;
curwp->w_marko = odoto;
curwp->w_flag |= WFMOVE;
return (TRUE);
}