344 lines
18 KiB
C
344 lines
18 KiB
C
/**
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* === DO NOT MODIFY THIS FILE ===
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* If you need some other prototypes or constants in a header, please put them
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* in another header file.
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*
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* When we grade, we will be replacing this file with our own copy.
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* You have been warned.
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* === DO NOT MODIFY THIS FILE ===
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*/
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#ifndef SFMM_H
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#define SFMM_H
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#include <stdbool.h>
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#include <stdint.h>
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#include <stdlib.h>
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/*
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Format of an allocated memory block
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+-----------------------------------------------------------------------------------------+
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| 64-bit-wide row |
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+-----------------------------------------------------------------------------------------+
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+----------------------------+----------------------+--------+--------+---------+---------+ <- header
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| payload size | block_size | unused | alloc |prv alloc|in qklst |
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| (0/1) |(4 LSB's implicitly 0)| (0) | (1) | (0/1) | (0) |
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| (32 bits) | (28 bits) | 1 bit | 1 bit | 1 bit | 1 bit |
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+---------------------------------------------------+--------+--------+---------+---------+ <- (aligned)
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| Payload and Padding |
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| (N rows) |
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+-----------------------------------------------------------------------------------------+
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NOTE: For an allocated block, there is no footer (it is used for payload).
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NOTE: The actual stored header is obfuscated by bitwise XOR'ing with MAGIC.
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The above diagram shows the un-obfuscated contents.
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*/
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/*
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Format of a memory block in a quick list
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+-----------------------------------------------------------------------------------------+
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| 64-bit-wide row |
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+-----------------------------------------------------------------------------------------+
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+----------------------------+----------------------+--------+--------+---------+---------+ <- header
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| unused | block_size | unused | alloc |prv alloc|in qklst |
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| (0) |(4 LSB's implicitly 0)| (0) | (1) | (0/1) | (1) |
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| (32 bits) | (28 bits) | 1 bit | 1 bit | 1 bit | 1 bit |
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+---------------------------------------------------+--------+--------+---------+---------+ <- (aligned)
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| Payload and Padding |
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| (N rows) |
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+-----------------------------------------------------------------------------------------+
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NOTE: For a block in a quick list, there is no footer.
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*/
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/*
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Format of a free memory block
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+----------------------------+----------------------+--------+--------+---------+---------+ <- header
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| unused | block_size | unused | alloc |prv alloc|in qklst |
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| (0) |(4 LSB's implicitly 0)| (0) | (0) | (0/1) | (0) |
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| (32 bits) | (28 bits) | 1 bit | 1 bit | 1 bit | 1 bit |
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+------------------------------------------------------------+--------+---------+---------+ <- (aligned)
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| Pointer to next free block |
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| (1 row) |
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+-----------------------------------------------------------------------------------------+
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| Pointer to previous free block |
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| (1 row) |
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+-----------------------------------------------------------------------------------------+
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| Unused |
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| (N rows) |
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+------------------------------------------------------------+--------+---------+---------+ <- footer
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| unused | block_size | unused | alloc |prv alloc|in qklst |
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| (0) |(4 LSB's implicitly 0)| (0) | (0) | (0/1) | (0) |
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| (32 bits) | (28 bits) | 1 bit | 1 bit | 1 bit | 1 bit |
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+------------------------------------------------------------+--------+---------+---------+
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NOTE: For a free block, footer contents must always be identical to header contents.
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NOTE: The actual stored footer is obfuscated by bitwise XOR'ing with MAGIC.
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The above diagram shows the un-obfuscated contents.
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*/
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#define IN_QUICK_LIST 0x1
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#define PREV_BLOCK_ALLOCATED 0x2
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#define THIS_BLOCK_ALLOCATED 0x4
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typedef uint32_t sf_size_t;
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typedef uint64_t sf_header;
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typedef sf_header sf_footer;
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/*
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* Structure of a block.
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* The first field of this structure is actually the footer of the *previous* block.
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* This must be taken into account when creating sf_block pointers from memory addresses.
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*/
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typedef struct sf_block {
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sf_footer prev_footer; // NOTE: This actually belongs to the *previous* block.
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sf_header header; // This is where the current block really starts.
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union {
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/* A free block contains links to other blocks in a free list. */
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struct {
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struct sf_block *next;
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struct sf_block *prev;
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} links;
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/* An allocated block contains a payload (aligned), starting here. */
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char payload[0]; // Length varies according to block size.
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} body;
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} sf_block;
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/*
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* The heap is designed to keep the payload area of each block aligned to a two-row (16-byte)
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* boundary. The header of a block precedes the payload area, and is only single-row (8-byte)
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* aligned. The first block of the heap starts as soon as possible after the beginning of the
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* heap, subject to the condition that its payload area is two-row aligned.
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*/
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/*
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Format of the heap
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+-----------------------------------------------------------------------------------------+
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| 64-bit-wide row |
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+-----------------------------------------------------------------------------------------+
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+-----------------------------------------------------------------------------------------+ <- heap start
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| | (aligned)
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| Unused |
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| (1 row) |
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+----------------------------+----------------------+--------+--------+---------+---------+ <- header
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| payload size |minimum block_size(32)| unused | alloc |prv alloc|in qklst |
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| (0) |(4 LSB's implicitly 0)| (0) | (1) | (0/1) | (0) | prologue block
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| (32 bits) | (28 bits) | 1 bit | 1 bit | 1 bit | 1 bit |
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+------------------------------------------------------------+--------+---------+---------+ <- (aligned)
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| |
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| Unused Payload Area |
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| (3 rows) |
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+------------------------------------------------------------+--------+---------+---------+ <- header
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| payload size | block_size | unused | alloc |prv alloc|in qklst |
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| (0/1) |(4 LSB's implicitly 0)| (0) | (0/1) | (0/1) | (0/1) | first block
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| (32 bits) | (28 bits) | 1 bit | 1 bit | 1 bit | 1 bit |
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+------------------------------------------------------------+--------+---------+---------+ <- (aligned)
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| Payload and Padding |
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| (N rows) |
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+--------------------------------------------+------------------------+---------+---------+
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| Additional allocated and free blocks |
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+-----------------------------------------------------------------------------------------+
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| payload size | block_size | unused | alloc |prv alloc|in qklst |
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| (0) | (0) | (0) | (1) | (0/1) | (0) | epilogue
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| (32 bits) | (28 bits) | 1 bit | 1 bit | 1 bit | 1 bit |
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+------------------------------------------------------------+--------+---------+---------+ <- heap_end
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(aligned)
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NOTE: The actual stored epilogue is obfuscated by bitwise XOR'ing with MAGIC.
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The above diagram shows the un-obfuscated contents.
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*/
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/* sf_errno: will be set on error */
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int sf_errno;
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/*
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* "Quick lists": These are used to hold recently freed blocks of small sizes, so that they
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* can be used to satisfy allocations without searching lists or splitting blocks.
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* Blocks on a quick list are marked as allocated, so they are not available for coalescing.
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* The number of blocks in any individual quick list is limited to QUICK_LIST_MAX.
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* If adding a block to a quick list would cause it to exceed QUICK_LIST_MAX, then the
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* list is flushed, returning the existing blocks in the list to the main pool, and then
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* the block being freed is added to the now-empty list, leaving that list containing one block.
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*
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* The quick lists are indexed by (size-MIN_BLOCK_SIZE)/ALIGN_SIZE, starting with blocks of the
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* minimum block size at index 0, blocks of size MIN_BLOCK_SIZE+ALIGN_SIZE at index 1, and so on.
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* They are maintained as singly linked lists, using a LIFO discipline.
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*/
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#define NUM_QUICK_LISTS 10 /* Number of quick lists. */
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#define QUICK_LIST_MAX 5 /* Maximum number of blocks permitted on a single quick list. */
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struct {
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int length; // Number of blocks currently in the list.
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struct sf_block *first; // Pointer to first block in the list.
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} sf_quick_lists[NUM_QUICK_LISTS];
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/*
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* Free blocks are maintained in a set of circular, doubly linked lists, segregated by
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* size class. The first list holds blocks of the minimum size M. The second list holds
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* blocks of size (M, 2M]. The third list holds blocks whose size is in the interval (2M, 4M].
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* The fourth list holds blocks whose size is in the interval (4M, 8M], and so on.
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* This continues up to the interval (128M, 256M], and then the last list holds all blocks
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* of size greater than 256M.
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*
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* Each of the circular, doubly linked lists has a "dummy" block used as the list header.
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* This dummy block is always linked between the last and the first element of the list.
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* In an empty list, the next and free pointers of the list header point back to itself.
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* In a list with something in it, the next pointer of the header points to the first node
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* in the list and the previous pointer of the header points to the last node in the list.
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* The header itself is never removed from the list and it contains no data (only the link
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* fields are used). The reason for doing things this way is to avoid edge cases in insertion
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* and deletion of nodes from the list.
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*/
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#define NUM_FREE_LISTS 10
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struct sf_block sf_free_list_heads[NUM_FREE_LISTS];
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/*
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* This is your implementation of sf_malloc. It acquires uninitialized memory that
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* is aligned and padded properly for the underlying system.
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*
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* @param size The number of bytes requested to be allocated.
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*
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* @return If size is 0, then NULL is returned without setting sf_errno.
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* If size is nonzero, then if the allocation is successful a pointer to a valid region of
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* memory of the requested size is returned. If the allocation is not successful, then
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* NULL is returned and sf_errno is set to ENOMEM.
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*/
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void *sf_malloc(sf_size_t size);
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/*
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* Resizes the memory pointed to by ptr to size bytes.
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*
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* @param ptr Address of the memory region to resize.
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* @param size The minimum size to resize the memory to.
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*
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* @return If successful, the pointer to a valid region of memory is
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* returned, else NULL is returned and sf_errno is set appropriately.
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*
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* If sf_realloc is called with an invalid pointer sf_errno should be set to EINVAL.
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* If there is no memory available sf_realloc should set sf_errno to ENOMEM.
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*
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* If sf_realloc is called with a valid pointer and a size of 0 it should free
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* the allocated block and return NULL without setting sf_errno.
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*/
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void *sf_realloc(void *ptr, sf_size_t size);
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/*
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* Marks a dynamically allocated region as no longer in use.
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* Adds the newly freed block to the free list.
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*
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* @param ptr Address of memory returned by the function sf_malloc.
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*
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* If ptr is invalid, the function calls abort() to exit the program.
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*/
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void sf_free(void *ptr);
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/*
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* Get the current amount of internal fragmentation of the heap.
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*
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* @return the current amount of internal fragmentation, defined to be the
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* ratio of the total amount of payload to the total size of allocated blocks.
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* If there are no allocated blocks, then the returned value should be 0.0.
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*/
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double sf_internal_fragmentation();
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/*
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* Get the peak memory utilization for the heap.
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*
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* @return the peak memory utilization over the interval starting from the
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* time the heap was initialized, up to the current time. The peak memory
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* utilization at a given time, as defined in the lecture and textbook,
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* is the ratio of the maximum aggregate payload up to that time, divided
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* by the current heap size. If the heap has not yet been initialized,
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* this function should return 0.0.
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*/
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double sf_peak_utilization();
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/* sfutil.c: Helper functions already created for this assignment. */
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/*
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* @return The starting address of the heap for your allocator.
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*/
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void *sf_mem_start();
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/*
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* @return The ending address of the heap for your allocator.
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*/
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void *sf_mem_end();
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/*
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* This function increases the size of your heap by adding one page of
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* memory to the end.
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*
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* @return On success, this function returns a pointer to the start of the
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* additional page, which is the same as the value that would have been returned
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* by get_heap_end() before the size increase. On error, NULL is returned.
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*/
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void *sf_mem_grow();
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/* The size of a page of memory returned by sf_mem_grow(). */
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#define PAGE_SZ ((sf_size_t)1024)
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/*
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* @return The "magic number" used to obfuscate header and footer contents
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* to make it difficult to free a block without having first succesfully
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* malloc'ed one.
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*/
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sf_header sf_magic();
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#define MAGIC (sf_magic())
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/*
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* Set the "magic number" used to obfuscate header and footer contents.
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* Setting the magic number to zero essentially turns off obfuscation, which will
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* to make your life easier during debugging. This function will be replaced
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* by a dummy version during grading, so be sure to test your code without calling
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* this function.
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*
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* @param magic The value to set the magic number to. Setting to 0x0 disables
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* obfuscation.
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*/
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void sf_set_magic(sf_header magic);
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/*
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* Display the contents of the heap in a human-readable form.
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*/
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void sf_show_block(sf_block *bp);
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void sf_show_blocks();
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void sf_show_free_list(int index);
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void sf_show_free_lists();
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void sf_show_quick_list(int index);
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void sf_show_quick_lists();
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void sf_show_heap();
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#endif
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