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#pragma once
// KBuffer: Statically sized kernel-only memory buffer.
//
// A KBuffer is a value-type convenience class that wraps a NonnullRefPtr<KBufferImpl>.
// The memory is allocated via the global kernel-only page allocator, rather than via
// kmalloc() which is what ByteBuffer/Vector/etc will use.
//
// This makes KBuffer a little heavier to allocate, but much better for large and/or
// long-lived allocations, since they don't put all that weight and pressure on the
// severely limited kmalloc heap.
#include <AK/Assertions.h>
#include <AK/LogStream.h>
#include <Kernel/VM/MemoryManager.h>
#include <Kernel/VM/Region.h>
class KBufferImpl : public RefCounted<KBufferImpl> {
public:
static NonnullRefPtr<KBufferImpl> create_with_size(size_t size, u8 access)
{
auto region = MM.allocate_kernel_region(PAGE_ROUND_UP(size), "KBuffer", access, false, false);
ASSERT(region);
return adopt(*new KBufferImpl(region.release_nonnull(), size));
}
static NonnullRefPtr<KBufferImpl> copy(const void* data, size_t size, u8 access)
{
auto buffer = create_with_size(size, access);
memcpy(buffer->data(), data, size);
return buffer;
}
u8* data() { return m_region->vaddr().as_ptr(); }
const u8* data() const { return m_region->vaddr().as_ptr(); }
size_t size() const { return m_size; }
size_t capacity() const { return m_region->size(); }
void set_size(size_t size)
{
ASSERT(size <= capacity());
m_size = size;
}
private:
explicit KBufferImpl(NonnullOwnPtr<Region>&& region, size_t size)
: m_size(size)
, m_region(move(region))
{
}
size_t m_size { 0 };
NonnullOwnPtr<Region> m_region;
};
class KBuffer {
public:
static KBuffer create_with_size(size_t size, u8 access = Region::Access::Read | Region::Access::Write)
{
return KBuffer(KBufferImpl::create_with_size(size, access));
}
static KBuffer copy(const void* data, size_t size, u8 access = Region::Access::Read | Region::Access::Write)
{
return KBuffer(KBufferImpl::copy(data, size, access));
}
u8* data() { return m_impl->data(); }
const u8* data() const { return m_impl->data(); }
size_t size() const { return m_impl->size(); }
size_t capacity() const { return m_impl->capacity(); }
void set_size(size_t size) { m_impl->set_size(size); }
const KBufferImpl& impl() const { return m_impl; }
KBuffer(const ByteBuffer& buffer, u8 access = Region::Access::Read | Region::Access::Write)
: m_impl(KBufferImpl::copy(buffer.data(), buffer.size(), access))
{
}
private:
explicit KBuffer(NonnullRefPtr<KBufferImpl>&& impl)
: m_impl(move(impl))
{
}
NonnullRefPtr<KBufferImpl> m_impl;
};
inline const LogStream& operator<<(const LogStream& stream, const KBuffer& value)
{
return stream << StringView(value.data(), value.size());
}
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