64 lines
1.8 KiB
C++
64 lines
1.8 KiB
C++
// Copyright (c) Vitaliy Filippov, 2023+
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// License: VNPL-1.1 or GNU GPL-2.0+ (see README.md for details)
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#include <assert.h>
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#include "freelist.h"
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uint64_t freelist_allocator_t::alloc(uint64_t data_size)
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{
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for (int i = 0; i < freelist.size(); i++)
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{
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if (freelist[i].size >= data_size)
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{
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uint64_t r = freelist[i].start;
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freelist[i].start += data_size;
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freelist[i].size -= data_size;
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return r;
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}
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}
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return UINT64_MAX;
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}
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void freelist_allocator_t::free(uint64_t start, uint64_t size)
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{
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int min = 0, max = freelist.size();
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if (max && freelist[freelist.size()-1].start < start)
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{
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min = max;
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}
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if (max && freelist[0].start >= start)
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{
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max = 0;
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}
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while (max-min > 1)
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{
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int mid = (min+max)/2;
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if (freelist[mid].start >= start)
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max = mid;
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else
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min = mid;
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}
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// max = the first item where freelist[max].start >= start
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if (max > 0 && freelist[max-1].start+freelist[max-1].size >= start)
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{
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assert(freelist[max-1].start+freelist[max-1].size == start);
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freelist[max-1].size += size;
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}
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else if (max < freelist.size() && freelist[max].start <= size+start)
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{
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assert(freelist[max].start == size+start);
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freelist[max].start -= size;
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freelist[max].size += size;
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}
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else
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{
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freelist.insert(freelist.begin()+min, (freelist_item_t){ .start = start, .size = size });
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max = min; // to skip the if below
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}
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if (min != max && max < freelist.size() && freelist[max].start == freelist[min].start+freelist[min].size)
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{
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freelist[min].size += freelist[max].size;
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freelist.erase(freelist.begin()+max, freelist.begin()+max+1);
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}
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}
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