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Kernel: Use a CircularQueue for input rather than a DoubleBuffer

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TTY::emit is called from an IRQ handler, and is used to push input data
into a buffer for later retrieval. Previously this was using DoubleBuffer,
but that class wants to take a lock. Our lock code wants to make sure
interrupts are enabled, but they're disabled while an IRQ handler is
running. This made the kernel sad, but this CircularQueue cheers it up by
avoiding the lock requirement completely.
This commit is contained in:
Conrad Pankoff 2019-08-12 21:32:28 +10:00 • committed by Andreas Kling
parent ce8387d1ed
commit 4b44962e03
2 changed files with 11 additions and 4 deletions
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12
Kernel/TTY/TTY.cpp
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@ -26,7 +26,13 @@ void TTY::set_default_termios()
ssize_t TTY::read(FileDescription&, u8* buffer, ssize_t size)
{
return m_buffer.read(buffer, size);
if (m_input_buffer.size() < size)
size = m_input_buffer.size();
for (int i = 0; i < size; i++)
buffer[i] = m_input_buffer.dequeue();
return size;
}
ssize_t TTY::write(FileDescription&, const u8* buffer, ssize_t size)
@ -44,7 +50,7 @@ ssize_t TTY::write(FileDescription&, const u8* buffer, ssize_t size)
bool TTY::can_read(FileDescription&) const
{
return !m_buffer.is_empty();
return !m_input_buffer.is_empty();
}
bool TTY::can_write(FileDescription&) const
@ -71,7 +77,7 @@ void TTY::emit(u8 ch)
return;
}
}
m_buffer.write(&ch, 1);
m_input_buffer.enqueue(ch);
}
void TTY::generate_signal(int signal)