mirror of
https://github.com/LadybirdBrowser/ladybird.git
synced 2024-11-26 01:20:25 +00:00
7d862dd5fc
String.h no longer pulls in StringView.h. We do this by moving a bunch of String functions out-of-line.
92 lines
3.3 KiB
C++
92 lines
3.3 KiB
C++
/*
|
|
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions are met:
|
|
*
|
|
* 1. Redistributions of source code must retain the above copyright notice, this
|
|
* list of conditions and the following disclaimer.
|
|
*
|
|
* 2. Redistributions in binary form must reproduce the above copyright notice,
|
|
* this list of conditions and the following disclaimer in the documentation
|
|
* and/or other materials provided with the distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
|
|
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
|
|
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
|
|
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
|
|
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
#include <AK/StringView.h>
|
|
#include <Kernel/DoubleBuffer.h>
|
|
|
|
namespace Kernel {
|
|
|
|
inline void DoubleBuffer::compute_lockfree_metadata()
|
|
{
|
|
InterruptDisabler disabler;
|
|
m_empty = m_read_buffer_index >= m_read_buffer->size && m_write_buffer->size == 0;
|
|
m_space_for_writing = m_capacity - m_write_buffer->size;
|
|
}
|
|
|
|
DoubleBuffer::DoubleBuffer(size_t capacity)
|
|
: m_write_buffer(&m_buffer1)
|
|
, m_read_buffer(&m_buffer2)
|
|
, m_storage(KBuffer::create_with_size(capacity * 2, Region::Access::Read | Region::Access::Write, "DoubleBuffer"))
|
|
, m_capacity(capacity)
|
|
{
|
|
m_buffer1.data = m_storage.data();
|
|
m_buffer1.size = 0;
|
|
m_buffer2.data = m_storage.data() + capacity;
|
|
m_buffer2.size = 0;
|
|
m_space_for_writing = capacity;
|
|
}
|
|
|
|
void DoubleBuffer::flip()
|
|
{
|
|
ASSERT(m_read_buffer_index == m_read_buffer->size);
|
|
swap(m_read_buffer, m_write_buffer);
|
|
m_write_buffer->size = 0;
|
|
m_read_buffer_index = 0;
|
|
compute_lockfree_metadata();
|
|
}
|
|
|
|
ssize_t DoubleBuffer::write(const u8* data, ssize_t size)
|
|
{
|
|
if (!size)
|
|
return 0;
|
|
ASSERT(size > 0);
|
|
LOCKER(m_lock);
|
|
ssize_t bytes_to_write = min(static_cast<size_t>(size), m_space_for_writing);
|
|
u8* write_ptr = m_write_buffer->data + m_write_buffer->size;
|
|
m_write_buffer->size += bytes_to_write;
|
|
compute_lockfree_metadata();
|
|
memcpy(write_ptr, data, bytes_to_write);
|
|
return bytes_to_write;
|
|
}
|
|
|
|
ssize_t DoubleBuffer::read(u8* data, ssize_t size)
|
|
{
|
|
if (!size)
|
|
return 0;
|
|
ASSERT(size > 0);
|
|
LOCKER(m_lock);
|
|
if (m_read_buffer_index >= m_read_buffer->size && m_write_buffer->size != 0)
|
|
flip();
|
|
if (m_read_buffer_index >= m_read_buffer->size)
|
|
return 0;
|
|
ssize_t nread = min((ssize_t)m_read_buffer->size - (ssize_t)m_read_buffer_index, size);
|
|
memcpy(data, m_read_buffer->data + m_read_buffer_index, nread);
|
|
m_read_buffer_index += nread;
|
|
compute_lockfree_metadata();
|
|
return nread;
|
|
}
|
|
|
|
}
|