diff options
Diffstat (limited to 'drivers/tty/vt/vt.c')
| -rw-r--r-- | drivers/tty/vt/vt.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c index a0b7576747cd..2eab714aab67 100644 --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -4279,6 +4279,44 @@ void vcs_scr_updated(struct vc_data *vc) notify_update(vc); } +void vc_scrolldelta_helper(struct vc_data *c, int lines, + unsigned int rolled_over, void *base, unsigned int size) +{ + unsigned long ubase = (unsigned long)base; + int margin = c->vc_size_row * 4; + int ul, we, p, st; + + /* Turn scrollback off */ + if (!lines) { + c->vc_visible_origin = c->vc_origin; + return; + } + + /* Do we have already enough to allow jumping from 0 to the end? */ + if (rolled_over > (c->vc_scr_end - ubase) + margin) { + ul = c->vc_scr_end - ubase; + we = rolled_over + c->vc_size_row; + } else { + ul = 0; + we = size; + } + + p = (c->vc_visible_origin - ubase - ul + we) % we + + lines * c->vc_size_row; + st = (c->vc_origin - ubase - ul + we) % we; + + /* Only a little piece would be left? Show all incl. the piece! */ + if (st < 2 * margin) + margin = 0; + if (p < margin) + p = 0; + if (p > st - margin) + p = st; + + c->vc_visible_origin = ubase + (p + ul) % we; +} +EXPORT_SYMBOL_GPL(vc_scrolldelta_helper); + /* * Visible symbols for modules */ |