Custom C implementation of the malloc\free library functions.
It exposes the following methods:
void *malloc(size_t size);
void free(void *ptr);
void *realloc(void *ptr, size_t size);
void *calloc(size_t count, size_t size);
void *realloc(void *ptr, size_t size);The general idea is that for every chunk of memory allocated by malloc, the we store a few bytes (specifically sizeof(mcb_t)) of metadata about that chunk right beforehand. We scan the entire heap and stop when we see the first available chunk. If we have not found a suitable fragment, we use the sbrk system call to request memory from the operating system. The sbrk directory contains a custom implementation of this function:
void *sbrk(size_t size);This project contains the implementation this idea.
This project contains the implementation Simple_allocator_lvl1 and also aligned and blocks splitting.
For faster access, a memory block should be aligned, and usually by the size of the machine word. if we found a block of a suitable size, we just use it. This might be inefficient in case if a found block is much larger than the requested one. We shall now implement a procedure of splitting a larger free block, taking from it only a smaller chunk, which is requested. The other part stays free, and can be used in further allocation requests.
This project contains the implementation Simple_allocator_lvl2 and also sorting the list of free blocks to combine adjacent blocks into one.