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Kernel: Handle backspace for tab character in TTY cooked mode

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Before, serenity would only backspace one character for a tab.
This is the only feature that my OS has and serenity doesn't.
This commit is contained in:
Peter Elliott 2021-10-06 00:58:09 -06:00 • committed by Andreas Kling
parent c515121844
commit 669b23ac0a
1 changed files with 23 additions and 5 deletions
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28
Kernel/TTY/TTY.cpp
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@ -280,14 +280,32 @@ bool TTY::can_do_backspace() const
return false;
}
static size_t length_with_tabs(CircularDeque<u8, TTY_BUFFER_SIZE> const& line)
{
size_t length = 0;
for (auto& ch : line) {
length += (ch == '\t') ? 8 - (length % 8) : 1;
}
return length;
}
void TTY::do_backspace()
{
if (can_do_backspace()) {
m_input_buffer.dequeue_end();
// We deliberately don't process the output here.
echo(8);
echo(' ');
echo(8);
auto ch = m_input_buffer.dequeue_end();
size_t to_delete = 1;
if (ch == '\t') {
auto length = length_with_tabs(m_input_buffer);
to_delete = 8 - (length % 8);
}
for (size_t i = 0; i < to_delete; ++i) {
// We deliberately don't process the output here.
echo('\b');
echo(' ');
echo('\b');
}
evaluate_block_conditions();
}