aae18fd035
The previous frame allocator involved a lot of splitting and merging linked lists and lost all information about frames while they were allocated. The new allocator is based on an array of descriptor structures and a bitmap. Each memory map region of allocatable memory becomes one or more descriptors, each mapping up to 1GiB of physical memory. The descriptors implement two levels of a bitmap tree, and have a pointer into the large contiguous bitmap to track individual pages.
51 lines
1.4 KiB
C++
51 lines
1.4 KiB
C++
#pragma once
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/// \file frame_allocator.h
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/// Allocator for physical memory frames
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#include <stdint.h>
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namespace kernel {
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namespace args {
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struct frame_block;
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}}
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/// Allocator for physical memory frames
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class frame_allocator
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{
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public:
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using frame_block = kernel::args::frame_block;
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/// Constructor
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/// \arg blocks The bootloader-supplied frame bitmap block list
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/// \arg count Number of entries in the block list
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frame_allocator(frame_block *frames, size_t count);
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/// Get free frames from the free list. Only frames from the first free block
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/// are returned, so the number may be less than requested, but they will
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/// be contiguous.
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/// \arg count The maximum number of frames to get
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/// \arg address [out] The physical address of the first frame
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/// \returns The number of frames retrieved
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size_t allocate(size_t count, uintptr_t *address);
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/// Free previously allocated frames.
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/// \arg address The physical address of the first frame to free
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/// \arg count The number of frames to be freed
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void free(uintptr_t address, size_t count);
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/// Mark frames as used
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/// \arg address The physical address of the first frame to free
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/// \arg count The number of frames to be freed
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void used(uintptr_t address, size_t count);
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/// Get the global frame allocator
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static frame_allocator & get();
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private:
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frame_block *m_blocks;
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long m_count;
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frame_allocator() = delete;
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frame_allocator(const frame_allocator &) = delete;
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};
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