310 lines
6.1 KiB
C
310 lines
6.1 KiB
C
/*
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* Copyright (C) 1984-2011 Mark Nudelman
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*
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* You may distribute under the terms of either the GNU General Public
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* License or the Less License, as specified in the README file.
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*
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* For more information about less, or for information on how to
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* contact the author, see the README file.
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*/
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/*
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* Routines which jump to a new location in the file.
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*/
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#include "less.h"
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#include "position.h"
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extern int jump_sline;
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extern int squished;
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extern int screen_trashed;
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extern int sc_width, sc_height;
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extern int show_attn;
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extern int top_scroll;
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/*
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* Jump to the end of the file.
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*/
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public void
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jump_forw()
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{
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POSITION pos;
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POSITION end_pos;
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if (ch_end_seek())
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{
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error("Cannot seek to end of file", NULL_PARG);
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return;
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}
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/*
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* Note; lastmark will be called later by jump_loc, but it fails
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* because the position table has been cleared by pos_clear below.
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* So call it here before calling pos_clear.
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*/
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lastmark();
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/*
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* Position the last line in the file at the last screen line.
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* Go back one line from the end of the file
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* to get to the beginning of the last line.
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*/
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pos_clear();
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end_pos = ch_tell();
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pos = back_line(end_pos);
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if (pos == NULL_POSITION)
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jump_loc((POSITION)0, sc_height-1);
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else
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{
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jump_loc(pos, sc_height-1);
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if (position(sc_height-1) != end_pos)
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repaint();
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}
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}
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/*
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* Jump to line n in the file.
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*/
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public void
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jump_back(linenum)
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LINENUM linenum;
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{
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POSITION pos;
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PARG parg;
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/*
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* Find the position of the specified line.
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* If we can seek there, just jump to it.
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* If we can't seek, but we're trying to go to line number 1,
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* use ch_beg_seek() to get as close as we can.
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*/
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pos = find_pos(linenum);
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if (pos != NULL_POSITION && ch_seek(pos) == 0)
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{
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if (show_attn)
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set_attnpos(pos);
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jump_loc(pos, jump_sline);
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} else if (linenum <= 1 && ch_beg_seek() == 0)
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{
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jump_loc(ch_tell(), jump_sline);
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error("Cannot seek to beginning of file", NULL_PARG);
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} else
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{
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parg.p_linenum = linenum;
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error("Cannot seek to line number %n", &parg);
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}
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}
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/*
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* Repaint the screen.
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*/
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public void
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repaint()
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{
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struct scrpos scrpos;
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/*
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* Start at the line currently at the top of the screen
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* and redisplay the screen.
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*/
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get_scrpos(&scrpos);
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pos_clear();
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jump_loc(scrpos.pos, scrpos.ln);
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}
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/*
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* Jump to a specified percentage into the file.
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*/
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public void
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jump_percent(percent, fraction)
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int percent;
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long fraction;
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{
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POSITION pos, len;
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/*
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* Determine the position in the file
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* (the specified percentage of the file's length).
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*/
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if ((len = ch_length()) == NULL_POSITION)
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{
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ierror("Determining length of file", NULL_PARG);
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ch_end_seek();
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}
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if ((len = ch_length()) == NULL_POSITION)
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{
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error("Don't know length of file", NULL_PARG);
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return;
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}
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pos = percent_pos(len, percent, fraction);
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if (pos >= len)
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pos = len-1;
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jump_line_loc(pos, jump_sline);
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}
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/*
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* Jump to a specified position in the file.
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* Like jump_loc, but the position need not be
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* the first character in a line.
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*/
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public void
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jump_line_loc(pos, sline)
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POSITION pos;
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int sline;
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{
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int c;
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if (ch_seek(pos) == 0)
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{
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/*
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* Back up to the beginning of the line.
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*/
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while ((c = ch_back_get()) != '\n' && c != EOI)
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;
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if (c == '\n')
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(void) ch_forw_get();
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pos = ch_tell();
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}
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if (show_attn)
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set_attnpos(pos);
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jump_loc(pos, sline);
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}
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/*
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* Jump to a specified position in the file.
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* The position must be the first character in a line.
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* Place the target line on a specified line on the screen.
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*/
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public void
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jump_loc(pos, sline)
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POSITION pos;
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int sline;
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{
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register int nline;
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POSITION tpos;
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POSITION bpos;
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/*
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* Normalize sline.
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*/
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sline = adjsline(sline);
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if ((nline = onscreen(pos)) >= 0)
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{
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/*
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* The line is currently displayed.
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* Just scroll there.
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*/
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nline -= sline;
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if (nline > 0)
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forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0);
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else
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back(-nline, position(TOP), 1, 0);
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#if HILITE_SEARCH
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if (show_attn)
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repaint_hilite(1);
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#endif
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return;
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}
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/*
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* Line is not on screen.
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* Seek to the desired location.
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*/
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if (ch_seek(pos))
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{
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error("Cannot seek to that file position", NULL_PARG);
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return;
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}
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/*
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* See if the desired line is before or after
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* the currently displayed screen.
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*/
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tpos = position(TOP);
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bpos = position(BOTTOM_PLUS_ONE);
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if (tpos == NULL_POSITION || pos >= tpos)
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{
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/*
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* The desired line is after the current screen.
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* Move back in the file far enough so that we can
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* call forw() and put the desired line at the
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* sline-th line on the screen.
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*/
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for (nline = 0; nline < sline; nline++)
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{
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if (bpos != NULL_POSITION && pos <= bpos)
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{
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/*
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* Surprise! The desired line is
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* close enough to the current screen
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* that we can just scroll there after all.
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*/
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forw(sc_height-sline+nline-1, bpos, 1, 0, 0);
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#if HILITE_SEARCH
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if (show_attn)
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repaint_hilite(1);
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#endif
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return;
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}
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pos = back_line(pos);
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if (pos == NULL_POSITION)
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{
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/*
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* Oops. Ran into the beginning of the file.
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* Exit the loop here and rely on forw()
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* below to draw the required number of
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* blank lines at the top of the screen.
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*/
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break;
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}
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}
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lastmark();
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squished = 0;
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screen_trashed = 0;
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forw(sc_height-1, pos, 1, 0, sline-nline);
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} else
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{
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/*
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* The desired line is before the current screen.
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* Move forward in the file far enough so that we
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* can call back() and put the desired line at the
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* sline-th line on the screen.
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*/
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for (nline = sline; nline < sc_height - 1; nline++)
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{
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pos = forw_line(pos);
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if (pos == NULL_POSITION)
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{
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/*
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* Ran into end of file.
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* This shouldn't normally happen,
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* but may if there is some kind of read error.
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*/
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break;
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}
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if (pos >= tpos)
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{
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/*
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* Surprise! The desired line is
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* close enough to the current screen
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* that we can just scroll there after all.
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*/
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back(nline+1, tpos, 1, 0);
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#if HILITE_SEARCH
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if (show_attn)
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repaint_hilite(1);
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#endif
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return;
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}
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}
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lastmark();
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if (!top_scroll)
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clear();
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else
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home();
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screen_trashed = 0;
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add_back_pos(pos);
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back(sc_height-1, pos, 1, 0);
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}
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}
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