Basic memory allocator interface - educational implementation. More...
#include <unistd.h>#include <climits>#include <cstdio>#include <cstring>#include <iostream>#include <stdexcept>
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Classes | |
| struct | hh::basic_alloc::MemNode |
| Metadata structure for each memory block. More... | |
Namespaces | |
| namespace | hh |
| namespace | hh::basic_alloc |
Typedefs | |
| using | hh::basic_alloc::MemSizeT = unsigned long long |
| Type definition for memory size. | |
Functions | |
| bool | hh::basic_alloc::is_free (MemSizeT &size) |
| Check if block is free using bit 63. | |
| void | hh::basic_alloc::make_free (MemSizeT &size) |
| Mark block as free by setting bit 63. | |
| void | hh::basic_alloc::make_used (MemSizeT &size) |
| Mark block as used by clearing bit 63. | |
| MemSizeT | hh::basic_alloc::get_size (MemSizeT &size) |
| Extract actual size by masking off bit 63. | |
| MemSizeT | hh::basic_alloc::add (MemSizeT a, MemSizeT b) |
| Add two sizes (clearing free bits first). | |
| MemSizeT | hh::basic_alloc::sub (MemSizeT a, MemSizeT b) |
| Subtract two sizes (clearing free bits first). | |
| void * | hh::basic_alloc::sbrk_then_alloc (MemSizeT size) |
| Request memory from OS using sbrk and allocate. | |
| void | hh::basic_alloc::coalesce_nodes (MemNode *nd) |
| Merge a free node with adjacent free nodes. | |
| void * | hh::basic_alloc::free (void *ptr) |
| Free a memory block and merge with adjacent free blocks. | |
| void | hh::basic_alloc::shrink_then_align (MemNode *nd, MemSizeT size) |
| Shrink a block and create a new free block from remainder. | |
| void * | hh::basic_alloc::try_alloc (MemSizeT size) |
| Allocate memory using first-fit strategy. | |
| void | hh::basic_alloc::mem_copy (void *dest, const void *src, size_t n) |
| Copy n bytes from source to destination. | |
| void * | hh::basic_alloc::try_realloc (void *ptr, MemSizeT size) |
| Reallocate a memory block to a new size. | |
| void | hh::basic_alloc::mem_set (void *ptr, int value, size_t num) |
| Set num bytes to specified value. | |
| void * | hh::basic_alloc::try_calloc (size_t num, size_t size) |
| Allocate and zero-initialize an array. | |
| void | hh::basic_alloc::alloc_print () |
| Print allocation status table for debugging. | |
Variables | |
| constexpr MemSizeT | hh::basic_alloc::MIN_FRAGMENT_SIZE = 32 |
| Minimum fragment size to consider splitting a block. | |
| constexpr MemSizeT | hh::basic_alloc::BLOCK_SIZE = 4096 |
| Size of each memory block requested from OS via sbrk. | |
| constexpr MemSizeT | hh::basic_alloc::MEM_NODE_SIZE = sizeof(MemNode) |
| Size of the MemNode structure. | |
Detailed Description
Basic memory allocator interface - educational implementation.
This file provides a simple linked-list-based memory allocator using sbrk() to request memory from the operating system. It uses first-fit allocation strategy and maintains a singly-linked list of free/used blocks.
- Warning
- NOT THREAD SAFE - do not use in multi-threaded environments
- VERY SLOW AND INEFFICIENT - for educational purposes only
- Production code should use halloc or standard allocators
Implementation details:
- Uses program break (sbrk) for memory acquisition
- First-fit allocation strategy (O(n) search)
- Automatic coalescing of adjacent free blocks
- Minimum fragment size to prevent excessive splitting
- Metadata stored before each allocated block
