/* * mm-naive.c - The fastest, least memory-efficient malloc package. * * In this naive approach, a block is allocated by simply incrementing * the brk pointer. A block is pure payload. There are no headers or * footers. Blocks are never coalesced or reused. Realloc is * implemented directly using mm_malloc and mm_free. * * NOTE TO STUDENTS: Replace this header comment with your own header * comment that gives a high level description of your solution. */ #include #include #include #include #include #include "mm.h" #include "memlib.h" /********************************************************* * NOTE TO STUDENTS: Before you do anything else, please * provide your team information in the following struct. ********************************************************/ team_t team = { /* Team name */ "anna.schlittenhardt@stud.uni-due.de+tuan-dat.tran@stud.uni-due.de", /* First member's full name */ "Anna Schlittenhardt", /* First member's email address */ "anna.schlittenhardt@stud.uni-due.de", /* Second member's full name (leave blank if none) */ "Tuan-Dat Tran", /* Second member's email address (leave blank if none) */ "tuan-dat.tran@stud.uni-due.de" }; //////////////////////////////////////////////////////////////////////////////// /////////////////////////////////// STRUCTURE ////////////////////////////////// //////////////////////////////////////////////////////////////////////////////// // Filled Blk // 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ // HEADER | SIZE | A| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ // BODY | ALLOCED MEMORY | // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ // FOOTER | SIZE | A| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ // // Empty Blk // 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ // HEADER | SIZE | A| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ // | PTR TO PREV FREE BLK | // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ // | PTR TO NEXT FREE BLK | // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ // BODY | UNALLOC MEMORY | // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ // FOOTER | SIZE | A| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ //////////////////////////////////////////////////////////////////////////////// //////////////////////////////////// DEFINES /////////////////////////////////// //////////////////////////////////////////////////////////////////////////////// /* single word (4) or double word (8) alignment */ #define ALIGNMENT 8 /* rounds up to the nearest multiple of ALIGNMENT */ #define ALIGN(size) (((size) + (ALIGNMENT-1)) & ~0x7) #define SIZE_T_SIZE (ALIGN(sizeof(size_t))) /* Page 830, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */ /* Basic constants and macros */ #define WSIZE 4 /* Word and header/footer size (bytes) */ #define DSIZE 8 /* Double word size (bytes) */ #define CHUNKSIZE (1<<12) /* Extend heap by this amount (bytes) */ #define MAX(x, y) ((x) > (y)? (x) : (y)) /* Pack a size and allocated bit into a word */ #define PACK(size, alloc) ((size) | (alloc)) /* Read and write a word at address p */ #define GET(p) (*(unsigned int *)(p)) #define PUT(p, val) (*(unsigned int *)(p) = (val)) /* Read the size and allocated fields from address p */ #define GET_SIZE(p) (GET(p) & ~0x7) #define GET_ALLOC(p) (GET(p) & 0x1) /* Given block ptr bp, compute address of its header and footer */ #define HDRP(bp) ((char *)(bp) - WSIZE) #define FTRP(bp) ((char *)(bp) + GET_SIZE(HDRP(bp)) - DSIZE) /* Given block ptr bp, compute address of next and previous blocks */ #define NEXT_BLKP(bp) ((char *)(bp) + GET_SIZE(((char *)(bp) - WSIZE))) #define PREV_BLKP(bp) ((char *)(bp) - GET_SIZE(((char *)(bp) - DSIZE))) //////////////////////////////////////////////////////////////////////////////// ////////////////////////////////// STATIC VARS ///////////////////////////////// //////////////////////////////////////////////////////////////////////////////// const size_t LIST_SIZE = 100; static char* heap_listp; static char* seg_list[LIST_SIZE]; //////////////////////////////////////////////////////////////////////////////// ///////////////////////////////// HELPER PREDEF //////////////////////////////// //////////////////////////////////////////////////////////////////////////////// /* Page 856-858, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */ static void place(void *bp, size_t asize); /* Page 856, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */ static void* find_fit(size_t asize); /* Page 833, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */ static void* coalesce(void *bp); /* Page 831, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */ static void* extend_heap(size_t words); /* Page 831, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */ //////////////////////////////////////////////////////////////////////////////// /////////////////////////////// HELPER FUNCTIONS /////////////////////////////// //////////////////////////////////////////////////////////////////////////////// static void place(void *bp, size_t asize) { size_t csize = GET_SIZE(HDRP(bp)); if ((csize - asize) >= (2*DSIZE)) { PUT(HDRP(bp), PACK(asize, 1)); PUT(FTRP(bp), PACK(asize, 1)); bp = NEXT_BLKP(bp); PUT(HDRP(bp), PACK(csize-asize, 0)); PUT(FTRP(bp), PACK(csize-asize, 0)); } else { PUT(HDRP(bp), PACK(csize, 1)); PUT(FTRP(bp), PACK(csize, 1)); } } static void* first_fit(size_t asize) { /* First fit search */ void *bp; for (bp = heap_listp; GET_SIZE(HDRP(bp)) > 0; bp = NEXT_BLKP(bp)) { if (!GET_ALLOC(HDRP(bp)) && (asize <= GET_SIZE(HDRP(bp)))) { return bp; } } return NULL; /* No fit */ } /* Page 856, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */ static void* find_fit(size_t asize) { return first_fit(asize); } /* Page 833, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */ static void *coalesce(void *bp) { size_t prev_alloc = GET_ALLOC(FTRP(PREV_BLKP(bp))); size_t next_alloc = GET_ALLOC(HDRP(NEXT_BLKP(bp))); size_t size = GET_SIZE(HDRP(bp)); if (prev_alloc && next_alloc) { /* Case 1 */ return bp; } else if (prev_alloc && !next_alloc) { /* Case 2 */ size += GET_SIZE(HDRP(NEXT_BLKP(bp))); PUT(HDRP(bp),PACK(size,0)); PUT(FTRP(bp),PACK(size,0)); } else if (!prev_alloc && next_alloc) { /* Case 3 */ size += GET_SIZE(HDRP(PREV_BLKP(bp))); PUT(FTRP(bp), PACK(size, 0)); PUT(HDRP(PREV_BLKP(bp)), PACK(size, 0)); bp = PREV_BLKP(bp); } else { /* Case 4 */ size += GET_SIZE(HDRP(PREV_BLKP(bp))) + GET_SIZE(FTRP(NEXT_BLKP(bp))); PUT(HDRP(PREV_BLKP(bp)), PACK(size, 0)); PUT(FTRP(NEXT_BLKP(bp)), PACK(size, 0)); bp = PREV_BLKP(bp); } return bp; } /* Page 831, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */ static void *extend_heap(size_t words) { char *bp; size_t size; /* Allocate an even number of words to maintain alignment */ size = (words % 2) ? (words+1) * WSIZE : words * WSIZE; if ((long)(bp = mem_sbrk(size)) == -1) return NULL; /* Initialize free block header/footer and the epilogue header */ PUT(HDRP(bp), PACK(size,0)); /* Free block header */ PUT(FTRP(bp), PACK(size,0)); /* Free block footer */ PUT(HDRP(NEXT_BLKP(bp)), PACK(0, 1)); /* New epilogue header */ /* Coalesce if the previous block was free */ return coalesce(bp); } //////////////////////////////////////////////////////////////////////////////// ////////////////////////////// MAIN FUNCTIONALITY ////////////////////////////// //////////////////////////////////////////////////////////////////////////////// /* Page 831, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */ /* * mm_init - initialize the malloc package. */ int mm_init(void) { for (size_t i = 0; i < LIST_SIZE; ++i) { seg_list[i] = NULL; } /* Create the initial empty heap */ if ((heap_listp = mem_sbrk(4*WSIZE)) == (void *)-1) return -1; PUT(heap_listp, 0); /* Alignment padding */ PUT(heap_listp + (1*WSIZE), PACK(DSIZE, 1)); /* Prologue header */ PUT(heap_listp + (2*WSIZE), PACK(DSIZE, 1)); /* Prologue footer */ PUT(heap_listp + (3*WSIZE), PACK(0, 1)); /* Epilogue header */ heap_listp += (2*WSIZE); /* Extend the empty heap with a free block of CHUNKSIZE bytes */ if (extend_heap(CHUNKSIZE/WSIZE) == NULL) return -1; return 0; } /* Page 834, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */ /* * mm_malloc - Allocate a block by incrementing the brk pointer. * Always allocate a block whose size is a multiple of the alignment. */ void *mm_malloc(size_t size) { size_t asize; /* Adjusted block size */ size_t extendsize; /* Amount to extend heap if no fit */ char *bp; /* Pointer */ /* Ignore spurious requests */ if (size == 0) return NULL; /* Adjust block size to include overhead and alignment reqs. */ if (size <= DSIZE) asize = 2*DSIZE; else asize = DSIZE * ((size + (DSIZE) + (DSIZE-1)) / DSIZE); /* Search the free list for a fit */ if ((bp = find_fit(asize)) != NULL) { place(bp, asize); return bp; } /* No fit found. Get more memory and place the block */ extendsize = MAX(asize,CHUNKSIZE); if ((bp = extend_heap(extendsize/WSIZE)) == NULL) return NULL; place(bp, asize); return bp; } /* Page 833, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */ /* * mm_free - Freeing a block does nothing. */ void mm_free(void *ptr) { size_t size= GET_SIZE(HDRP(ptr)); PUT(HDRP(ptr), PACK(size, 0)); PUT(FTRP(ptr), PACK(size, 0)); coalesce(ptr); } /* * mm_realloc - Implemented simply in terms of mm_malloc and mm_free */ void *mm_realloc(void *ptr, size_t size) { /* * ATTENTION: You do not need to implement realloc for this assignment */ void *oldptr = ptr; void *newptr; size_t copySize; newptr = mm_malloc(size); if (newptr == NULL) return NULL; copySize = *(size_t *)((char *)oldptr - SIZE_T_SIZE); if (size < copySize) copySize = size; memcpy(newptr, oldptr, copySize); mm_free(oldptr); return newptr; }