inline static int read_gap_backward_v1(long *read_tap)
{
/* examine, if previous gap was long
by rewinding until 3 non-zero-values
in a row found, then reading forward (FIXME???)
*/
int non_zeros_in_a_row = 0;
long remember_file_seek_position;
remember_file_seek_position = current_image->current_file_seek_position;
current_image->current_file_seek_position -= 4;
next_tap -= 4;
while ((non_zeros_in_a_row < 3) && current_image->current_file_seek_position) {
if (!datasette_move_buffer_back(-1)) {
return 1;
}
current_image->current_file_seek_position--;
next_tap--;
if (tap_buffer[next_tap]) {
non_zeros_in_a_row++;
} else {
non_zeros_in_a_row = 0;
}
}
/* now forward */
while (current_image->current_file_seek_position < remember_file_seek_position - 4) {
if (!datasette_move_buffer_forward(1)) {
return -1;
}
if (tap_buffer[next_tap]) {
current_image->current_file_seek_position++;
next_tap++;
} else {
current_image->current_file_seek_position += 4;
next_tap += 4;
}
}
if (!datasette_move_buffer_forward(4)) {
return -1;
}
*read_tap = next_tap;
next_tap += (remember_file_seek_position - current_image->current_file_seek_position);
current_image->current_file_seek_position = remember_file_seek_position;
return 0;
}
static CLOCK datasette_read_gap(int direction)
{
/* direction 1: forward, -1: rewind */
long read_tap = 0;
CLOCK gap = 0;
/* if (current_image->system != 2 || current_image->version != 1
|| !fullwave) {*/
if (current_image->system != 2 ) {
if ((direction < 0) && !datasette_move_buffer_back(direction * 4))
return 0;
if ((direction > 0 ) && !datasette_move_buffer_forward(direction * 4))
return 0;
if (direction > 0) {
read_gap_forward(&read_tap);
} else {
if ((current_image->version == 0) || (next_tap < 4)
|| tap_buffer[next_tap-4]) {
read_gap_backward_v0(&read_tap);
} else {
if (read_gap_backward_v1(&read_tap) < 0)
return 0;
}
}
if (fetch_gap(&gap, &direction, read_tap) < 0)
return 0;
next_tap += direction;
current_image->current_file_seek_position += direction;
}
if (current_image->system == 2 && current_image->version == 1) {
if (!fullwave) {
if ((direction < 0) && !datasette_move_buffer_back(direction * 4))
return 0;
if ((direction > 0 ) && !datasette_move_buffer_forward(direction * 4))
return 0;
if (direction > 0) {
read_gap_forward(&read_tap);
} else {
if ((current_image->version == 0) || (next_tap < 4)
|| tap_buffer[next_tap-4]) {
read_gap_backward_v0(&read_tap);
} else {
if (read_gap_backward_v1(&read_tap) < 0)
return 0;
}
}
if (fetch_gap(&gap, &direction, read_tap) < 0)
return 0;
fullwave_gap = gap;
next_tap += direction;
current_image->current_file_seek_position += direction;
} else {
gap = fullwave_gap;
}
fullwave ^= 1;
} else if (current_image->system == 2 && current_image->version == 2) {
if ((direction < 0) && !datasette_move_buffer_back(direction * 4))
return 0;
if ((direction > 0 ) && !datasette_move_buffer_forward(direction * 4))
return 0;
if (direction > 0) {
read_gap_forward(&read_tap);
} else {
if ((current_image->version == 0) || (next_tap < 4)
|| tap_buffer[next_tap-4]) {
read_gap_backward_v0(&read_tap);
} else {
if (read_gap_backward_v1(&read_tap) < 0)
return 0;
}
}
if (fetch_gap(&gap, &direction, read_tap) < 0)
return 0;
gap *= 2;
fullwave ^= 1;
next_tap += direction;
current_image->current_file_seek_position += direction;
}
return gap;
}
