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/*
* Copyright (c) 2021, Sahan Fernando <sahan.h.fernando@gmail.com>.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/Library/UserOrKernelBuffer.h>
#include <Kernel/Memory/MemoryManager.h>
#include <Kernel/Memory/RingBuffer.h>
namespace Kernel::Memory {
ErrorOr<NonnullOwnPtr<RingBuffer>> RingBuffer::try_create(StringView region_name, size_t capacity)
{
auto region_size = TRY(page_round_up(capacity));
auto region = TRY(MM.allocate_contiguous_kernel_region(region_size, region_name, Region::Access::Read | Region::Access::Write));
return adopt_nonnull_own_or_enomem(new (nothrow) RingBuffer(move(region), capacity));
}
RingBuffer::RingBuffer(NonnullOwnPtr<Memory::Region> region, size_t capacity)
: m_region(move(region))
, m_capacity_in_bytes(capacity)
{
}
bool RingBuffer::copy_data_in(UserOrKernelBuffer const& buffer, size_t offset, size_t length, PhysicalAddress& start_of_copied_data, size_t& bytes_copied)
{
size_t start_of_free_area = (m_start_of_used + m_num_used_bytes) % m_capacity_in_bytes;
bytes_copied = min(m_capacity_in_bytes - m_num_used_bytes, min(m_capacity_in_bytes - start_of_free_area, length));
if (bytes_copied == 0)
return false;
if (auto result = buffer.read(m_region->vaddr().offset(start_of_free_area).as_ptr(), offset, bytes_copied); result.is_error())
return false;
m_num_used_bytes += bytes_copied;
start_of_copied_data = m_region->physical_page(start_of_free_area / PAGE_SIZE)->paddr().offset(start_of_free_area % PAGE_SIZE);
return true;
}
ErrorOr<size_t> RingBuffer::copy_data_out(size_t size, UserOrKernelBuffer& buffer) const
{
auto start = m_start_of_used % m_capacity_in_bytes;
auto num_bytes = min(min(m_num_used_bytes, size), m_capacity_in_bytes - start);
TRY(buffer.write(m_region->vaddr().offset(start).as_ptr(), num_bytes));
return num_bytes;
}
ErrorOr<PhysicalAddress> RingBuffer::reserve_space(size_t size)
{
if (m_capacity_in_bytes < m_num_used_bytes + size)
return ENOSPC;
size_t start_of_free_area = (m_start_of_used + m_num_used_bytes) % m_capacity_in_bytes;
m_num_used_bytes += size;
PhysicalAddress start_of_reserved_space = m_region->physical_page(start_of_free_area / PAGE_SIZE)->paddr().offset(start_of_free_area % PAGE_SIZE);
return start_of_reserved_space;
}
void RingBuffer::reclaim_space(PhysicalAddress chunk_start, size_t chunk_size)
{
VERIFY(start_of_used() == chunk_start);
VERIFY(m_num_used_bytes >= chunk_size);
m_num_used_bytes -= chunk_size;
m_start_of_used += chunk_size;
}
PhysicalAddress RingBuffer::start_of_used() const
{
size_t start = m_start_of_used % m_capacity_in_bytes;
return m_region->physical_page(start / PAGE_SIZE)->paddr().offset(start % PAGE_SIZE);
}
}
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