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Kernel: Allow PS2MouseDevice to read multiple packets

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We were overwriting the start of the output buffer over and over when
reading multiple mouse packets.
This commit is contained in:
Andreas Kling 2020-02-07 11:25:12 +01:00
parent f24a6a7574
commit 083b81a566
Notes: sideshowbarker 2024-07-19 09:33:08 +09:00 
Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/083b81a566f
1 changed files with 8 additions and 9 deletions
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17
Kernel/Devices/PS2MouseDevice.cpp
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@ -361,21 +361,20 @@ bool PS2MouseDevice::can_read(const FileDescription&) const
ssize_t PS2MouseDevice::read(FileDescription&, u8* buffer, ssize_t size)
{
ssize_t nread = 0;
while (nread < size) {
if (m_queue.is_empty())
break;
// Don't return partial data frames.
if ((size - nread) < (ssize_t)sizeof(MousePacket))
break;
ASSERT(size > 0);
size_t nread = 0;
size_t remaining_space_in_buffer = static_cast<size_t>(size) - nread;
while (!m_queue.is_empty() && remaining_space_in_buffer) {
auto packet = m_queue.dequeue();
#ifdef PS2MOUSE_DEBUG
dbgprintf("PS2 Mouse Read: Buttons %x\n", packet.buttons);
dbgprintf("PS2 Mouse Read: X %d, Y %d, Z %d, Relative %d\n", packet.x, packet.y, packet.z, packet.buttons);
dbgprintf("PS2 Mouse Read: Filter packets\n");
#endif
memcpy(buffer, &packet, sizeof(MousePacket));
nread += sizeof(MousePacket);
size_t bytes_read_from_packet = min(remaining_space_in_buffer, sizeof(MousePacket));
memcpy(buffer + nread, &packet, bytes_read_from_packet);
nread += bytes_read_from_packet;
remaining_space_in_buffer -= bytes_read_from_packet;
}
return nread;
}