janwas
5919fc7877
. allocators: add static_calloc. also: documention was duplicated in header; merge it. . wdir_watch: fix last remaining static object init issues . add rationale and explanations to lib_errors, wsdl, qpc, whrt. . cpu/ia32: remove throttling detection (hacky); will be taken care of by tsc. . ia32: expose vendor . wdbg_sym: add its own critical section (safer, less contention) This was SVN commit r5114.
668 lines
17 KiB
C++
668 lines
17 KiB
C++
/**
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* =========================================================================
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* File : allocators.h
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* Project : 0 A.D.
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* Description : memory suballocators.
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* =========================================================================
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*/
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// license: GPL; see lib/license.txt
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#ifndef INCLUDED_ALLOCATORS
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#define INCLUDED_ALLOCATORS
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#include <map>
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#include "lib/posix/posix_mman.h" // PROT_*
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#include "lib/sysdep/cpu.h" // CAS
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//
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// page aligned allocator
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//
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/**
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* allocate memory aligned to the system page size.
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*
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* this is useful for file_buf_alloc, which uses this allocator to
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* get sector-aligned (hopefully; see file_sector_size) IO buffers.
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*
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* note that this allocator is stateless and very litte error checking
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* can be performed.
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*
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* the memory is initially writable and you can use mprotect to set other
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* access permissions if desired.
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*
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* @param unaligned_size minimum size [bytes] to allocate.
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* @return page-aligned and -padded memory or 0 on error / out of memory.
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**/
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extern void* page_aligned_alloc(size_t unaligned_size);
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/**
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* free a previously allocated page-aligned region.
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*
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* @param p exact value returned from page_aligned_alloc
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* @param size exact value passed to page_aligned_alloc
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**/
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extern void page_aligned_free(void* p, size_t unaligned_size);
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//
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// dynamic (expandable) array
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//
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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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extern 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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extern 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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extern 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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extern 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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extern 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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extern 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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extern 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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extern LibError da_append(DynArray* da, const void* data_src, size_t size);
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//
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// pool allocator
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//
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/**
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* allocator design parameters:
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* - O(1) alloc and free;
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* - either fixed- or variable-sized blocks;
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* - doesn't preallocate the entire pool;
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* - returns sequential addresses.
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*
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* opaque! do not read/write any fields!
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**/
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struct Pool
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{
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DynArray da;
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/**
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* size of elements. = 0 if pool set up for variable-sized
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* elements, otherwise rounded up to pool alignment.
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**/
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size_t el_size;
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/**
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* pointer to freelist (opaque); see freelist_*.
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* never used (remains 0) if elements are of variable size.
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**/
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void* freelist;
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};
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/**
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* pass as pool_create's <el_size> param to indicate variable-sized allocs
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* are required (see below).
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**/
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const size_t POOL_VARIABLE_ALLOCS = ~0u;
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/**
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* Ready Pool for use.
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*
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* @param Pool*
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* @param max_size Max size [bytes] of the Pool; this much
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* (rounded up to next page multiple) virtual address space is reserved.
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* no virtual memory is actually committed until calls to pool_alloc.
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* @param el_size Number of bytes that will be returned by each
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* pool_alloc (whose size parameter is then ignored). Can be 0 to
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* allow variable-sized allocations, but pool_free is then unusable.
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* @return LibError
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**/
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extern LibError pool_create(Pool* p, size_t max_size, size_t el_size);
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/**
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* free all memory (address space + physical) that constitutes the
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* given Pool.
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*
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* future alloc and free calls on this pool will fail.
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* continued use of the allocated memory (*) is
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* impossible because it is marked not-present via MMU.
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* (* no matter if in freelist or unused or "allocated" to user)
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*
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* @param Pool*
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* @return LibError.
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**/
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extern LibError pool_destroy(Pool* p);
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/**
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* indicate whether a pointer was allocated from the given pool.
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*
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* this is useful for callers that use several types of allocators.
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*
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* @param Pool*
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* @return bool.
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**/
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extern bool pool_contains(Pool* p, void* el);
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/**
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* Dole out memory from the pool.
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* exhausts the freelist before returning new entries to improve locality.
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*
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* @param Pool*
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* @param size bytes to allocate; ignored if pool_create's el_size was not 0.
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* @return allocated memory, or 0 if the Pool would have to be expanded and
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* there isn't enough memory to do so.
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**/
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extern void* pool_alloc(Pool* p, size_t size);
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/**
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* Make a fixed-size element available for reuse in the given Pool.
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*
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* this is not allowed if the Pool was created for variable-size elements.
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* rationale: avoids having to pass el_size here and compare with size when
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* allocating; also prevents fragmentation and leaking memory.
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*
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* @param Pool*
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* @param el Element returned by pool_alloc.
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**/
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extern void pool_free(Pool* p, void* el);
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/**
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* "free" all user allocations that ensued from the given Pool.
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*
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* this resets it as if freshly pool_create-d, but doesn't release the
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* underlying reserved virtual memory.
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*
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* @param Pool*
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**/
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extern void pool_free_all(Pool* p);
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//
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// bucket allocator
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//
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/**
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* allocator design goals:
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* - either fixed- or variable-sized blocks;
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* - allow freeing individual blocks if they are all fixed-size;
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* - never relocates;
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* - no fixed limit.
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*
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* note: this type of allocator is called "region-based" in the literature.
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* see "Reconsidering Custom Memory Allocation" (Berger, Zorn, McKinley).
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* if individual variable-size elements must be freeable, consider "reaps":
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* basically a combination of region and heap, where frees go to the heap and
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* allocs exhaust that memory first and otherwise use the region.
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*
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* opaque! do not read/write any fields!
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**/
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struct Bucket
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{
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/**
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* currently open bucket.
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**/
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u8* bucket;
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/**
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* offset of free space at end of current bucket (i.e. # bytes in use).
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**/
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size_t pos;
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void* freelist;
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size_t el_size : 16;
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/**
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* records # buckets allocated; verifies the list of buckets is correct.
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**/
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uint num_buckets : 16;
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};
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/**
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* ready the Bucket object for use.
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*
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* @param Bucket*
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* @param el_size 0 to allow variable-sized allocations (which cannot be
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* freed individually); otherwise, it specifies the number of bytes that
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* will be returned by bucket_alloc (whose size parameter is then ignored).
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* @return LibError.
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**/
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extern LibError bucket_create(Bucket* b, size_t el_size);
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/**
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* free all memory that ensued from <b>.
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*
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* future alloc and free calls on this Bucket will fail.
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*
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* @param Bucket*
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**/
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extern void bucket_destroy(Bucket* b);
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/**
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* Dole out memory from the Bucket.
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* exhausts the freelist before returning new entries to improve locality.
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*
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* @param Bucket*
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* @param size bytes to allocate; ignored if bucket_create's el_size was not 0.
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* @return allocated memory, or 0 if the Bucket would have to be expanded and
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* there isn't enough memory to do so.
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**/
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extern void* bucket_alloc(Bucket* b, size_t size);
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/**
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* make an entry available for reuse in the given Bucket.
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*
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* this is not allowed if created for variable-size elements.
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* rationale: avoids having to pass el_size here and compare with size when
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* allocating; also prevents fragmentation and leaking memory.
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*
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* @param Bucket*
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* @param el entry allocated via bucket_alloc.
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**/
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extern void bucket_free(Bucket* b, void* el);
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//
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// matrix allocator
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//
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/**
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* allocate a 2D matrix accessible as matrix[col][row].
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*
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* takes care of the dirty work of allocating 2D matrices:
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* - aligns data
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* - only allocates one memory block, which is more efficient than
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* malloc/new for each row.
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*
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* @param cols, rows: dimension (cols x rows)
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* @param el_size size [bytes] of a matrix cell
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* @return 0 if out of memory, otherwise matrix that should be cast to
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* type** (sizeof(type) == el_size). must be freed via matrix_free.
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**/
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extern void** matrix_alloc(uint cols, uint rows, size_t el_size);
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/**
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* free the given matrix.
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*
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* @param matrix allocated by matrix_alloc; no-op if 0.
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* callers will likely want to pass variables of a different type
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* (e.g. int**); they must be cast to void**.
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**/
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extern void matrix_free(void** matrix);
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//
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// allocator optimized for single instances
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//
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/**
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* Allocate <size> bytes of zeroed memory.
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*
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* intended for applications that frequently alloc/free a single
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* fixed-size object. caller provides static storage and an in-use flag;
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* we use that memory if available and otherwise fall back to the heap.
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* if the application only has one object in use at a time, malloc is
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* avoided; this is faster and avoids heap fragmentation.
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*
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* note: thread-safe despite use of shared static data.
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*
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* @param storage Caller-allocated memory of at least <size> bytes
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* (typically a static array of bytes)
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* @param in_use_flag Pointer to a flag we set when <storage> is in-use.
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* @param size [bytes] to allocate
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* @return allocated memory (typically = <storage>, but falls back to
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* malloc if that's in-use), or 0 (with warning) if out of memory.
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**/
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extern void* single_calloc(void* storage, volatile uintptr_t* in_use_flag, size_t size);
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/**
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* Free a memory block that had been allocated by single_calloc.
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*
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* @param storage Exact value passed to single_calloc.
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* @param in_use_flag Exact value passed to single_calloc.
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* @param Exact value returned by single_calloc.
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**/
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extern void single_free(void* storage, volatile uintptr_t* in_use_flag, void* p);
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#ifdef __cplusplus
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/**
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* C++ wrapper on top of single_calloc that's slightly easier to use.
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*
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* T must be POD (Plain Old Data) because it is memset to 0!
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**/
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template<class T> class SingleAllocator
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{
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T storage;
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volatile uintptr_t is_in_use;
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public:
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SingleAllocator()
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{
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is_in_use = 0;
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}
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T* alloc()
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{
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return (T*)single_calloc(&storage, &is_in_use, sizeof(storage));
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}
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void release(T* p)
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{
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single_free(&storage, &is_in_use, p);
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}
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};
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#endif // #ifdef __cplusplus
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//
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// static allocator
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//
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// dole out chunks of memory from storage reserved in the BSS.
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// freeing isn't necessary.
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/**
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* opaque; initialized by STATIC_STORAGE and used by static_calloc
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**/
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struct StaticStorage
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{
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void* pos;
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void* end;
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};
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// define <size> bytes of storage and prepare <name> for use with
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// static_calloc.
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// must be invoked from file or function scope.
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#define STATIC_STORAGE(name, size)\
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static u8 storage[(size)];\
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static StaticStorage name = { storage, storage+(size) }
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/*
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usage example:
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static Object* pObject;
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void InitObject()
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{
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STATIC_STORAGE(ss, 100); // includes padding
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void* addr = static_calloc(ss, sizeof(Object));
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pObject = new(addr) Object;
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}
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*/
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/**
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* dole out memory from static storage reserved in BSS.
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*
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* this is useful for static objects that are used before _cinit - callers
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* define static storage for one or several objects, use this function to
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* retrieve an aligned pointer, then construct there via placement new.
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*
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* @param ss - initialized via STATIC_STORAGE
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* @param size [bytes] to allocate
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* @return aligned (suitable for any type) pointer
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*
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* raises a warning if there's not enough room (indicates incorrect usage)
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**/
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extern void* static_calloc(StaticStorage* ss, size_t size);
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// (no need to free static_calloc-ed memory since it's in the BSS)
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//
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// overrun protection
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//
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/**
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OverrunProtector wraps an arbitrary object in DynArray memory and can detect
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inadvertent writes to it. this is useful for tracking down memory overruns.
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the basic idea is to require users to request access to the object and
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notify us when done; memory access permission is temporarily granted.
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(similar in principle to Software Transaction Memory).
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since this is quite slow, the protection is disabled unless
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CONFIG_OVERRUN_PROTECTION == 1; this avoids having to remove the
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wrapper code in release builds and re-write when looking for overruns.
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example usage:
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OverrunProtector<your_class> your_class_wrapper;
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..
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your_class* yc = your_class_wrapper.get(); // unlock, make ready for use
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if(!yc) // your_class_wrapper's one-time alloc of a your_class-
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abort(); // instance had failed - can't continue.
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doSomethingWith(yc); // read/write access
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your_class_wrapper.lock(); // disallow further access until next .get()
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..
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**/
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#ifdef REDEFINED_NEW
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# include "lib/nommgr.h"
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#endif
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template<class T> class OverrunProtector
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{
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DynArray da;
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T* cached_ptr;
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uintptr_t initialized;
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public:
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OverrunProtector()
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|
{
|
|
memset(&da, 0, sizeof(da));
|
|
cached_ptr = 0;
|
|
initialized = 0;
|
|
}
|
|
|
|
~OverrunProtector()
|
|
{
|
|
shutdown();
|
|
}
|
|
|
|
void lock()
|
|
{
|
|
#if CONFIG_OVERRUN_PROTECTION
|
|
da_set_prot(&da, PROT_NONE);
|
|
#endif
|
|
}
|
|
|
|
private:
|
|
void unlock()
|
|
{
|
|
#if CONFIG_OVERRUN_PROTECTION
|
|
da_set_prot(&da, PROT_READ|PROT_WRITE);
|
|
#endif
|
|
}
|
|
|
|
void init()
|
|
{
|
|
if(da_alloc(&da, sizeof(T)) < 0)
|
|
{
|
|
fail:
|
|
WARN_ERR(ERR::NO_MEM);
|
|
return;
|
|
}
|
|
if(da_set_size(&da, sizeof(T)) < 0)
|
|
goto fail;
|
|
|
|
cached_ptr = new(da.base) T();
|
|
lock();
|
|
}
|
|
|
|
void shutdown()
|
|
{
|
|
if(!CAS(&initialized, 1, 2))
|
|
return; // never initialized or already shut down - abort
|
|
unlock();
|
|
cached_ptr->~T(); // call dtor (since we used placement new)
|
|
cached_ptr = 0;
|
|
(void)da_free(&da);
|
|
}
|
|
|
|
public:
|
|
T* get()
|
|
{
|
|
// this could theoretically be done in the ctor, but we try to
|
|
// minimize non-trivial code at NLSO ctor time
|
|
// (avoids init order problems).
|
|
if(CAS(&initialized, 0, 1))
|
|
init();
|
|
debug_assert(initialized != 2 && "OverrunProtector: used after dtor called:");
|
|
unlock();
|
|
return cached_ptr;
|
|
}
|
|
};
|
|
#ifdef REDEFINED_NEW
|
|
# include "lib/mmgr.h"
|
|
#endif
|
|
|
|
|
|
//
|
|
// allocator test rig
|
|
//
|
|
|
|
/**
|
|
* allocator test rig.
|
|
* call from each allocator operation to sanity-check them.
|
|
* should only be used during debug mode due to serious overhead.
|
|
**/
|
|
class AllocatorChecker
|
|
{
|
|
public:
|
|
void notify_alloc(void* p, size_t size)
|
|
{
|
|
const Allocs::value_type item = std::make_pair(p, size);
|
|
std::pair<Allocs::iterator, bool> ret = allocs.insert(item);
|
|
debug_assert(ret.second == true); // wasn't already in map
|
|
}
|
|
|
|
void notify_free(void* p, size_t size)
|
|
{
|
|
Allocs::iterator it = allocs.find(p);
|
|
if(it == allocs.end())
|
|
debug_warn("AllocatorChecker: freeing invalid pointer");
|
|
else
|
|
{
|
|
// size must match what was passed to notify_alloc
|
|
const size_t allocated_size = it->second;
|
|
debug_assert(size == allocated_size);
|
|
|
|
allocs.erase(it);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* allocator is resetting itself, i.e. wiping out all allocs.
|
|
**/
|
|
void notify_clear()
|
|
{
|
|
allocs.clear();
|
|
}
|
|
|
|
private:
|
|
typedef std::map<void*, size_t> Allocs;
|
|
Allocs allocs;
|
|
};
|
|
|
|
#endif // #ifndef INCLUDED_ALLOCATORS
|