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/*
* Copyright (c) 2021, Sahan Fernando <sahan.h.fernando@gmail.com>.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/UserOrKernelBuffer.h>
#include <Kernel/VM/MemoryManager.h>
#include <Kernel/VM/RingBuffer.h>
namespace Kernel {
RingBuffer::RingBuffer(String region_name, size_t capacity)
: m_region(MM.allocate_contiguous_kernel_region(page_round_up(capacity), move(region_name), Region::Access::Read | Region::Access::Write))
, m_capacity_in_bytes(capacity)
{
}
bool RingBuffer::copy_data_in(const UserOrKernelBuffer& 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 (buffer.read(m_region->vaddr().offset(start_of_free_area).as_ptr(), offset, bytes_copied)) {
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;
}
return false;
}
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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