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/***************************************************************************
* COPYRIGHT NOTICE *
****************************************************************************
* ncurses is copyright (C) 1992-1995 *
* Zeyd M. Ben-Halim *
* zmbenhal@netcom.com *
* Eric S. Raymond *
* esr@snark.thyrsus.com *
* *
* Permission is hereby granted to reproduce and distribute ncurses *
* by any means and for any fee, whether alone or as part of a *
* larger distribution, in source or in binary form, PROVIDED *
* this notice is included with any such distribution, and is not *
* removed from any of its header files. Mention of ncurses in any *
* applications linked with it is highly appreciated. *
* *
* ncurses comes AS IS with no warranty, implied or expressed. *
* *
***************************************************************************/
/*
** lib_scroll.c
**
** The routine wscrl(win, n).
** positive n scroll the window up (ie. move lines down)
** negative n scroll the window down (ie. move lines up)
**
*/
#include "curses.priv.h"
#include <stdlib.h>
#include <string.h>
void _nc_scroll_window(WINDOW *win, int const n, short const top, short const bottom)
{
int line, j;
chtype blank = _nc_render(win, ' ', BLANK);
TR(TRACE_MOVE, ("_nc_scroll_window(%p, %d, %d, %d)", win, n, top,bottom));
/*
* This used to do a line-text pointer-shuffle instead of text copies.
* That (a) doesn't work when the window is derived and doesn't have
* its own storage, (b) doesn't save you a lot on modern machines
* anyway. Your typical memcpy implementations are coded in
* assembler using a tight BLT loop; for the size of copies we're
* talking here, the total execution time is dominated by the one-time
* setup cost. So there is no point in trying to be excessively
* clever -- esr.
*/
/* shift n lines downwards */
if (n < 0) {
for (line = bottom; line >= top-n; line--) {
memcpy(win->_line[line].text,
win->_line[line+n].text,
(size_t)(sizeof(chtype) * (win->_maxx+1)));
win->_line[line].oldindex = win->_line[line+n].oldindex;
}
for (line = top; line < top-n; line++) {
for (j = 0; j <= win->_maxx; j ++)
win->_line[line].text[j] = blank;
win->_line[line].oldindex = _NEWINDEX;
win->_line[line].firstchar = 0;
win->_line[line].lastchar = win->_maxx;
}
}
/* shift n lines upwards */
if (n > 0) {
for (line = top; line <= bottom-n; line++) {
memcpy(win->_line[line].text,
win->_line[line+n].text,
(size_t)(sizeof(chtype) * (win->_maxx+1)));
win->_line[line].oldindex = win->_line[line+n].oldindex;
}
for (line = bottom; line > bottom-n; line--) {
for (j = 0; j <= win->_maxx; j ++)
win->_line[line].text[j] = blank;
win->_line[line].oldindex = _NEWINDEX;
win->_line[line].firstchar = 0;
win->_line[line].lastchar = win->_maxx;
}
}
}
int
wscrl(WINDOW *win, int n)
{
T(("wscrl(%p,%d) called", win, n));
if (! win->_scroll)
return ERR;
if (n == 0)
return OK;
if ((n > (win->_regbottom - win->_regtop)) ||
(-n > (win->_regbottom - win->_regtop)))
return ERR;
_nc_scroll_window(win, n, win->_regtop, win->_regbottom);
touchline(win, win->_regtop, (int)(win->_regbottom - win->_regtop + 1));
_nc_synchook(win);
return OK;
}
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