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Add a DoubleBuffer thingy to allow TTY read/write to be interleaved.

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I feel like this concept might be useful in more places. It's very naive
right now and uses dynamically growing buffers. It should really use static
size buffers and never kmalloc().
This commit is contained in:
Andreas Kling 2018-11-16 17:56:18 +01:00
parent 52d1822c3c
commit d2046e79cf
3 changed files with 63 additions and 12 deletions
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42
Kernel/TTY.cpp
View file

@ -4,6 +4,32 @@
#include <LibC/signal_numbers.h>
#include <LibC/sys/ioctl_numbers.h>
void DoubleBuffer::flip()
{
ASSERT(m_read_buffer_index == m_read_buffer->size());
swap(m_read_buffer, m_write_buffer);
m_write_buffer->clear();
m_read_buffer_index = 0;
}
Unix::ssize_t DoubleBuffer::write(const byte* data, size_t size)
{
m_write_buffer->append(data, size);
return size;
}
Unix::ssize_t DoubleBuffer::read(byte* data, size_t size)
{
if (m_read_buffer_index >= m_read_buffer->size() && !m_write_buffer->isEmpty())
flip();
if (m_read_buffer_index >= m_read_buffer->size())
return 0;
ssize_t nread = min(m_read_buffer->size() - m_read_buffer_index, size);
memcpy(data, m_read_buffer->data() + m_read_buffer_index, nread);
m_read_buffer_index += nread;
return nread;
}
TTY::TTY(unsigned major, unsigned minor)
: CharacterDevice(major, minor)
{
@ -17,15 +43,7 @@ TTY::~TTY()
ssize_t TTY::read(byte* buffer, size_t size)
{
ssize_t nread = min(m_buffer.size(), size);
memcpy(buffer, m_buffer.data(), nread);
if (nread == (ssize_t)m_buffer.size())
m_buffer.clear();
else {
kprintf("had %u, read %u\n", m_buffer.size(), nread);
ASSERT_NOT_REACHED();
}
return nread;
return m_buffer.read(buffer, size);
}
ssize_t TTY::write(const byte* buffer, size_t size)
@ -36,12 +54,12 @@ ssize_t TTY::write(const byte* buffer, size_t size)
bool TTY::hasDataAvailableForRead() const
{
return !m_buffer.isEmpty();
return !m_buffer.is_empty();
}
void TTY::emit(byte ch)
{
m_buffer.append(ch);
m_buffer.write(&ch, 1);
}
void TTY::interrupt()
@ -93,6 +111,8 @@ int TTY::ioctl(Process& process, unsigned request, unsigned arg)
*tp = m_termios;
return 0;
case TCSETS:
case TCSETSF:
case TCSETSW:
tp = reinterpret_cast<Unix::termios*>(arg);
if (!process.validate_read(tp, sizeof(Unix::termios)))
return -EFAULT;