From 13d5cdcd08e82d6dbca23aed124e63677e5a2ae7 Mon Sep 17 00:00:00 2001 From: Sahan Fernando Date: Thu, 13 May 2021 00:58:05 +1000 Subject: [PATCH] Kernel: Create VM::RingBuffer class --- Kernel/CMakeLists.txt | 1 + Kernel/VM/RingBuffer.cpp | 47 ++++++++++++++++++++++++++++++++++++++++ Kernel/VM/RingBuffer.h | 33 ++++++++++++++++++++++++++++ 3 files changed, 81 insertions(+) create mode 100644 Kernel/VM/RingBuffer.cpp create mode 100644 Kernel/VM/RingBuffer.h diff --git a/Kernel/CMakeLists.txt b/Kernel/CMakeLists.txt index 5d904c1439..3e699f4ea3 100644 --- a/Kernel/CMakeLists.txt +++ b/Kernel/CMakeLists.txt @@ -236,6 +236,7 @@ set(KERNEL_SOURCES VM/Range.cpp VM/RangeAllocator.cpp VM/Region.cpp + VM/RingBuffer.cpp VM/ScatterGatherList.cpp VM/SharedInodeVMObject.cpp VM/Space.cpp diff --git a/Kernel/VM/RingBuffer.cpp b/Kernel/VM/RingBuffer.cpp new file mode 100644 index 0000000000..e33f40271a --- /dev/null +++ b/Kernel/VM/RingBuffer.cpp @@ -0,0 +1,47 @@ +/* + * Copyright (c) 2021, Sahan Fernando . + * + * SPDX-License-Identifier: BSD-2-Clause + */ + +#include +#include +#include + +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); +} + +} diff --git a/Kernel/VM/RingBuffer.h b/Kernel/VM/RingBuffer.h new file mode 100644 index 0000000000..53258b45cb --- /dev/null +++ b/Kernel/VM/RingBuffer.h @@ -0,0 +1,33 @@ +/* + * Copyright (c) 2021, Sahan Fernando . + * + * SPDX-License-Identifier: BSD-2-Clause + */ + +#pragma once + +#include +#include + +namespace Kernel { + +class RingBuffer { +public: + RingBuffer(String region_name, size_t capacity); + + bool has_space() const { return m_num_used_bytes < m_capacity_in_bytes; } + bool copy_data_in(const UserOrKernelBuffer& buffer, size_t offset, size_t length, PhysicalAddress& start_of_copied_data, size_t& bytes_copied); + void reclaim_space(PhysicalAddress chunk_start, size_t chunk_size); + PhysicalAddress start_of_used() const; + + SpinLock& lock() { return m_lock; } + +private: + OwnPtr m_region; + SpinLock m_lock; + size_t m_start_of_used {}; + size_t m_num_used_bytes {}; + size_t m_capacity_in_bytes {}; +}; + +}