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