forked from 0ad/0ad
145 lines
4.0 KiB
C
145 lines
4.0 KiB
C
/* Copyright (C) 2009 Wildfire Games.
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* This file is part of 0 A.D.
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*
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* 0 A.D. is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* 0 A.D. is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* dynamic (expandable) array
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*/
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#ifndef INCLUDED_DYNARRAY
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#define INCLUDED_DYNARRAY
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/**
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* provides a memory range that can be expanded but doesn't waste
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* physical memory or relocate itself.
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*
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* works by preallocating address space and committing as needed.
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* used as a building block for other allocators.
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**/
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struct DynArray
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{
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u8* base;
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size_t max_size_pa; /// reserved
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size_t cur_size; /// committed
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size_t cur_size_pa;
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/**
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* mprotect flags applied to newly committed pages
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**/
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int prot;
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size_t pos;
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};
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/**
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* ready the DynArray object for use.
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*
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* no virtual memory is actually committed until calls to da_set_size.
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*
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* @param da DynArray.
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* @param max_size size [bytes] of address space to reserve (*);
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* the DynArray can never expand beyond this.
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* (* rounded up to next page size multiple)
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* @return LibError.
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**/
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LIB_API LibError da_alloc(DynArray* da, size_t max_size);
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/**
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* free all memory (address space + physical) that constitutes the
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* given array.
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*
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* use-after-free is impossible because the memory is unmapped.
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*
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* @param DynArray* da; zeroed afterwards.
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* @return LibError
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**/
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LIB_API LibError da_free(DynArray* da);
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/**
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* expand or shrink the array: changes the amount of currently committed
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* (i.e. usable) memory pages.
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*
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* @param da DynArray.
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* @param new_size target size (rounded up to next page multiple).
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* pages are added/removed until this is met.
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* @return LibError.
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**/
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LIB_API LibError da_set_size(DynArray* da, size_t new_size);
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/**
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* Make sure at least <size> bytes starting at da->pos are committed and
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* ready for use.
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*
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* @param DynArray*
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* @param size Minimum amount to guarantee [bytes]
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* @return LibError
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**/
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LIB_API LibError da_reserve(DynArray* da, size_t size);
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/**
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* change access rights of the array memory.
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*
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* used to implement write-protection. affects the currently committed
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* pages as well as all subsequently added pages.
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*
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* @param da DynArray.
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* @param prot a combination of the PROT_* values used with mprotect.
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* @return LibError.
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**/
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LIB_API LibError da_set_prot(DynArray* da, int prot);
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/**
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* "wrap" (i.e. store information about) the given buffer in a DynArray.
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*
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* this is used to allow calling da_read or da_append on normal buffers.
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* da_free should be called when the DynArray is no longer needed,
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* even though it doesn't free this memory (but does zero the DynArray).
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*
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* @param da DynArray. Note: any future operations on it that would
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* change the underlying memory (e.g. da_set_size) will fail.
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* @param p target memory (no alignment/padding requirements)
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* @param size maximum size (no alignment requirements)
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* @return LibError.
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**/
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LIB_API LibError da_wrap_fixed(DynArray* da, u8* p, size_t size);
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/**
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* "read" from array, i.e. copy into the given buffer.
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*
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* starts at offset DynArray.pos and advances this.
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*
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* @param da DynArray.
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* @param data_dst destination memory
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* @param size [bytes] to copy
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* @return LibError.
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**/
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LIB_API LibError da_read(DynArray* da, void* data_dst, size_t size);
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/**
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* "write" to array, i.e. copy from the given buffer.
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*
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* starts at offset DynArray.pos and advances this.
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*
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* @param da DynArray.
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* @param data_src source memory
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* @param size [bytes] to copy
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* @return LibError.
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**/
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LIB_API LibError da_append(DynArray* da, const void* data_src, size_t size);
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#endif // #ifndef INCLUDED_DYNARRAY
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