basic_alloc.cpp File Reference

Implementation of basic linked-list memory allocator. More...

#include "basic_alloc.hpp"
#include <unistd.h>
#include <climits>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <stdexcept>

Include dependency graph for basic_alloc.cpp:

Namespaces
namespace	hh
namespace	hh::basic_alloc

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
MemNode *	hh::basic_alloc::__head = nullptr
	Pointer to the head of the memory block linked list.
MemNode *	hh::basic_alloc::__tail = nullptr

Detailed Description

Implementation of basic linked-list memory allocator.

This file implements a simple educational memory allocator using:

• Doubly-linked list of blocks (free and used)
• First-fit allocation strategy
• sbrk() for memory acquisition
• Automatic coalescing of adjacent free blocks
• Bit 63 of size field for free/used flag

Warning

NOT for production use - educational purposes only