132 lines
4.3 KiB
C++
132 lines
4.3 KiB
C++
/*****************************************************************************************[Alloc.h]
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Copyright (c) 2008-2010, Niklas Sorensson
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Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
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associated documentation files (the "Software"), to deal in the Software without restriction,
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including without limitation the rights to use, copy, modify, merge, publish, distribute,
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sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all copies or
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substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
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NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
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DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
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OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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**************************************************************************************************/
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#ifndef Minisat_Alloc_h
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#define Minisat_Alloc_h
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#include "XAlloc.h"
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#include "Vec.h"
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namespace Minisat {
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//=================================================================================================
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// Simple Region-based memory allocator:
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template<class T>
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class RegionAllocator
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{
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T* memory;
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uint32_t sz;
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uint32_t cap;
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uint32_t wasted_;
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void capacity(uint32_t min_cap);
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public:
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// TODO: make this a class for better type-checking?
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typedef uint32_t Ref;
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enum { Ref_Undef = UINT32_MAX };
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enum { Unit_Size = sizeof(T) };
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explicit RegionAllocator(uint32_t start_cap = 1024*1024) : memory(NULL), sz(0), cap(0), wasted_(0){ capacity(start_cap); }
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~RegionAllocator()
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{
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if (memory != NULL)
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::free(memory);
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}
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uint32_t size () const { return sz; }
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uint32_t wasted () const { return wasted_; }
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Ref alloc (int size);
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void free (int size) { wasted_ += size; }
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// Deref, Load Effective Address (LEA), Inverse of LEA (AEL):
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T& operator[](Ref r) { assert(r < sz); return memory[r]; }
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const T& operator[](Ref r) const { assert(r < sz); return memory[r]; }
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T* lea (Ref r) { assert(r < sz); return &memory[r]; }
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const T* lea (Ref r) const { assert(r < sz); return &memory[r]; }
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Ref ael (const T* t) { assert((void*)t >= (void*)&memory[0] && (void*)t < (void*)&memory[sz-1]);
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return (Ref)(t - &memory[0]); }
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void moveTo(RegionAllocator& to) {
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if (to.memory != NULL) ::free(to.memory);
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to.memory = memory;
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to.sz = sz;
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to.cap = cap;
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to.wasted_ = wasted_;
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memory = NULL;
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sz = cap = wasted_ = 0;
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}
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};
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template<class T>
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void RegionAllocator<T>::capacity(uint32_t min_cap)
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{
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if (cap >= min_cap) return;
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uint32_t prev_cap = cap;
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while (cap < min_cap){
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// NOTE: Multiply by a factor (13/8) without causing overflow, then add 2 and make the
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// result even by clearing the least significant bit. The resulting sequence of capacities
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// is carefully chosen to hit a maximum capacity that is close to the '2^32-1' limit when
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// using 'uint32_t' as indices so that as much as possible of this space can be used.
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uint32_t delta = ((cap >> 1) + (cap >> 3) + 2) & ~1;
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cap += delta;
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if (cap <= prev_cap)
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throw OutOfMemoryException();
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}
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// printf(" .. (%p) cap = %u\n", this, cap);
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assert(cap > 0);
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memory = (T*)xrealloc(memory, sizeof(T)*cap);
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}
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template<class T>
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typename RegionAllocator<T>::Ref
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RegionAllocator<T>::alloc(int size)
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{
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// printf("ALLOC called (this = %p, size = %d)\n", this, size); fflush(stdout);
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assert(size > 0);
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capacity(sz + size);
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uint32_t prev_sz = sz;
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sz += size;
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// Handle overflow:
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if (sz < prev_sz)
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throw OutOfMemoryException();
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return prev_sz;
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}
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//=================================================================================================
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}
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#endif
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