gno/bin/less/jump.c

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/*
* Routines which jump to a new location in the file.
*/
#pragma noroot
#include "less.h"
#include "position.h"
#ifdef _ORCAC_
segment "LoadSegONE";
#endif
extern int hit_eof;
extern int jump_sline;
extern int squished;
extern int screen_trashed;
extern int sc_width, sc_height;
/*
* Jump to the end of the file.
*/
public void
jump_forw(void)
{
POSITION pos;
if (ch_end_seek())
{
error("Cannot seek to end of file", NULL_PARG);
return;
}
/*
* Position the last line in the file at the last screen line.
* Go back one line from the end of the file
* to get to the beginning of the last line.
*/
pos = back_line(ch_tell());
if (pos == NULL_POSITION)
jump_loc((POSITION)0, sc_height-1);
else
jump_loc(pos, sc_height-1);
}
/*
* Jump to line n in the file.
*/
public void
jump_back(n)
int n;
{
POSITION pos;
PARG parg;
/*
* Find the position of the specified line.
* If we can seek there, just jump to it.
* If we can't seek, but we're trying to go to line number 1,
* use ch_beg_seek() to get as close as we can.
*/
pos = find_pos(n);
if (pos != NULL_POSITION && ch_seek(pos) == 0)
{
jump_loc(pos, jump_sline);
} else if (n <= 1 && ch_beg_seek() == 0)
{
jump_loc(ch_tell(), jump_sline);
error("Cannot seek to beginning of file", NULL_PARG);
} else
{
parg.p_int = n;
error("Cannot seek to line number %d", &parg);
}
}
/*
* Repaint the screen.
*/
public void
repaint(void)
{
struct scrpos scrpos;
/*
* Start at the line currently at the top of the screen
* and redisplay the screen.
*/
get_scrpos(&scrpos);
pos_clear();
jump_loc(scrpos.pos, scrpos.ln);
}
/*
* Jump to a specified percentage into the file.
*/
public void
jump_percent(percent)
int percent;
{
POSITION pos, len;
/*
* Determine the position in the file
* (the specified percentage of the file's length).
*/
if ((len = ch_length()) == NULL_POSITION)
{
error("Don't know length of file", NULL_PARG);
return;
}
/*
* {{ This calculation may overflow! }}
*/
pos = (percent * len) / 100;
if (pos >= len)
pos = len-1;
jump_line_loc(pos, jump_sline);
}
/*
* Jump to a specified position in the file.
* Like jump_loc, but the position need not be
* the first character in a line.
*/
public void
jump_line_loc(pos, sline)
POSITION pos;
int sline;
{
int c;
if (ch_seek(pos) == 0)
{
/*
* Back up to the beginning of the line.
*/
/* while ((c = ch_back_get()) != '\n' && c != EOI) */
while ((c = ch_back_get()) != '\r' && c != '\n' && c != EOI)
;
/* if (c == '\n') */
if (c == '\r' || c == '\n')
(void) ch_forw_get();
pos = ch_tell();
}
jump_loc(pos, sline);
}
/*
* Jump to a specified position in the file.
* The position must be the first character in a line.
* Place the target line on a specified line on the screen.
*/
public void
jump_loc(pos, sline)
POSITION pos;
int sline;
{
register int nline;
POSITION tpos;
POSITION bpos;
/*
* Normalize sline.
*/
sline = adjsline(sline);
if ((nline = onscreen(pos)) >= 0)
{
/*
* The line is currently displayed.
* Just scroll there.
*/
nline -= sline;
if (nline > 0)
forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0);
else
back(-nline, position(TOP), 1, 0);
return;
}
/*
* Line is not on screen.
* Seek to the desired location.
*/
if (ch_seek(pos))
{
error("Cannot seek to that file position", NULL_PARG);
return;
}
/*
* See if the desired line is before or after
* the currently displayed screen.
*/
tpos = position(TOP);
bpos = position(BOTTOM_PLUS_ONE);
if (tpos == NULL_POSITION || pos >= tpos)
{
/*
* The desired line is after the current screen.
* Move back in the file far enough so that we can
* call forw() and put the desired line at the
* sline-th line on the screen.
*/
for (nline = 0; nline < sline; nline++)
{
if (bpos != NULL_POSITION && pos <= bpos)
{
/*
* Surprise! The desired line is
* close enough to the current screen
* that we can just scroll there after all.
*/
forw(sc_height-sline+nline-1, bpos, 1, 0, 0);
return;
}
pos = back_line(pos);
if (pos == NULL_POSITION)
{
/*
* Oops. Ran into the beginning of the file.
* Exit the loop here and rely on forw()
* below to draw the required number of
* blank lines at the top of the screen.
*/
break;
}
}
lastmark();
hit_eof = 0;
squished = 0;
screen_trashed = 0;
forw(sc_height-1, pos, 1, 0, sline-nline);
} else
{
/*
* The desired line is before the current screen.
* Move forward in the file far enough so that we
* can call back() and put the desired line at the
* sline-th line on the screen.
*/
for (nline = sline; nline < sc_height - 1; nline++)
{
pos = forw_line(pos);
if (pos == NULL_POSITION)
{
/* Cannot happen! */
error("Program error: EOI in jump_loc (forw)",
NULL_PARG);
quit(1);
}
if (pos >= tpos)
{
/*
* Surprise! The desired line is
* close enough to the current screen
* that we can just scroll there after all.
*/
back(nline+1, tpos, 1, 0);
return;
}
}
lastmark();
clear();
screen_trashed = 0;
add_back_pos(pos);
back(sc_height-1, pos, 1, 0);
}
}