inline int buf_del(struct buffer *b)
{
if( b->e == b->s ){
return -1;
}
b->s = buf_inc(b->s, b->size);
return 0;
}
inline int buf_add(struct buffer *b)
{
unsigned int tmp = buf_inc(b->e, b->size);
if( tmp != b->s ){
b->e = tmp;
return 0;
}
return -1;
}
/* Puts the given char into the given terminal's buffer, moving the
* cursor accordingly for control chars Returns 1 if char can be
* echoed (non-control char), 0 otherwise */
static int
vt_handle_char(virtterm_t *vt, char c)
{
KASSERT(NULL != vt);
/* Start where the cursor currently is located */
int new_cursor = vt->vt_cursor;
int ret = 0;
switch (c) {
case '\b': /* Move cursor back one space */
/* the user can't backspace past the beginning */
if (new_cursor != vt->vt_head)
buf_dec(new_cursor);
break;
case '\r':
new_cursor = (new_cursor / DISPLAY_WIDTH) * DISPLAY_WIDTH;
break;
/* In the next two cases, the cursor advances, and we
* need to compare it with the end of the buffer to
* determine whether or not to advance the buffer
* tail */
case '\n': /* To beginning of next line */
new_cursor = next_row(new_cursor);
goto handle_tail;
default:
/* Actually put a char into the buffer */
vt->vt_buf[new_cursor] = c;
/* And increment */
buf_inc(new_cursor);
ret = 1;
handle_tail: /* Yuck */
if (circ_dist(new_cursor, vt->vt_cursor) >=
circ_dist(vt->vt_tail, vt->vt_cursor)) {
/* Current cursor pos past tail of the current
* buffer, so advance tail */
int new_tail = next_row(new_cursor);
/* Check for head adjusting (if we write
* enough that the scroll buffer fills up, we
* sacrifice chars near the head) */
if (circ_dist(vt->vt_tail, vt->vt_head) >=
circ_dist(vt->vt_tail, new_tail)) {
vt->vt_head = next_row(new_tail);
}
/* Remember to clear space we may have acquired */
if (vt->vt_tail <= new_tail) {
memset(vt->vt_buf + vt->vt_tail,
0, new_tail - vt->vt_tail);
} else {
memset(vt->vt_buf + vt->vt_tail,
0, SCROLL_BUFSIZE - vt->vt_tail);
memset(vt->vt_buf, 0, new_tail);
}
/* Finally, set the new tail */
vt->vt_tail = new_tail;
}
break;
}
vt->vt_cursor = new_cursor;
return ret;
}
