/*
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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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"ateam",
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/* First member's full name */
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"Deng Bohao",
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/* First member's email address */
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"10225501432@stu.ecnu.edu.cn",
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/* Second member's full name (leave blank if none) */
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"Deng Bohao",
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/* Second member's email address (leave blank if none) */
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"10225501432@stu.ecnu.edu.cn"
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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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/* 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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/* Pack a size and allocated bit into 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 and write a pointer at address p */
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#define GET_PTR(p) ((unsigned int *)(long)(GET(p)))
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#define PUT_PTR(p, ptr) (*(unsigned int *)(p) = ((long)ptr))
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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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/* 每个free list中块的大小范围 */
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#define SIZE1 (1<<4)
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#define SIZE2 (1<<5)
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#define SIZE3 (1<<6)
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#define SIZE4 (1<<7)
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#define SIZE5 (1<<8)
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#define SIZE6 (1<<9)
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#define SIZE7 (1<<10) /* 1 KB */
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#define SIZE8 (1<<11)
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#define SIZE9 (1<<12)
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#define SIZE10 (1<<13)
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#define SIZE11 (1<<14)
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#define SIZE12 (1<<15)
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#define SIZE13 (1<<16)
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#define SIZE14 (1<<17)
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#define SIZE15 (1<<18)
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#define SIZE16 (1<<19)
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#define SIZE17 (1<<20) /* 1 MB */
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#define LISTS_NUM 18 /* free list 的数量 */
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/* Globe var */
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static char *heap_listp;
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/* 函数声明 */
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static void *extend_heap(size_t words);
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static void *coalesce(void *bp);
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static void *find_fit(size_t asize);
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static void place(void *bp, size_t asize);
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static void insert_list(void *bp);
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int getListOffset(size_t size);
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void delete_list(void *bp);
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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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char *bp;
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int i;
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if ((heap_listp = mem_sbrk((LISTS_NUM + 4) * WSIZE)) == (void *)-1) {
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return -1;
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}
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PUT(heap_listp + LISTS_NUM * WSIZE, 0);
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PUT(heap_listp + (1 + LISTS_NUM) * WSIZE, PACK(DSIZE, 1));
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PUT(heap_listp + (2 + LISTS_NUM) * WSIZE, PACK(DSIZE, 1));
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PUT(heap_listp + (3 + LISTS_NUM) * WSIZE, PACK(0, 1));
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for (i = 0; i < LISTS_NUM; i++) {
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PUT_PTR(heap_listp + WSIZE * i, NULL);
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}
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/* Extend the empty heap with a free block of CHUNKSIZE bytes */
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if ((bp = extend_heap(CHUNKSIZE / WSIZE)) == NULL) {
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return -1;
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}
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return 0;
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}
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/*
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* 扩展heap的大小
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*/
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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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/* 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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}
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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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/* 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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* 合并free block
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*/
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void *coalesce(void *bp)
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{
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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) { /* 前后都分配了 */
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bp = bp;
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} else if (prev_alloc && !next_alloc) { /* 前分配, 后未分配 */
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delete_list(NEXT_BLKP(bp));
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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) { /* 前未分配, 后分配 */
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delete_list(PREV_BLKP(bp));
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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 { /* 前后都未分配 */
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delete_list(NEXT_BLKP(bp));
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delete_list(PREV_BLKP(bp));
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size = size + GET_SIZE(HDRP(PREV_BLKP(bp))) +
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GET_SIZE(HDRP(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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insert_list(bp);
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return bp;
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}
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/*
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* mm_malloc - Allocate a block by searching the free list.
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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;
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/* Igore spurious requests */
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if (0 == size) {
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return NULL;
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}
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/* Adjusted 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 = DSIZE * ((size + (DSIZE) + (DSIZE - 1)) / DSIZE);
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}
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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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}
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place(bp, asize);
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return bp;
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}
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/*
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* getListOffset - 得到大小为size的块应该在哪个list中
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*/
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int getListOffset(size_t size)
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{
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if (size <= SIZE1) {
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return 0;
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} else if (size <= SIZE2) {
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return 1;
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} else if (size <= SIZE3) {
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return 2;
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} else if (size <= SIZE4) {
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return 3;
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} else if (size <= SIZE5) {
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return 4;
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} else if (size <= SIZE6) {
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return 5;
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} else if (size <= SIZE7) {
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return 6;
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} else if (size <= SIZE8) {
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return 7;
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} else if (size <= SIZE9) {
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return 8;
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} else if (size <= SIZE10) {
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return 9;
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} else if (size <= SIZE11) {
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return 10;
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} else if (size <= SIZE12) {
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return 11;
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} else if (size <= SIZE13) {
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return 12;
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} else if (size <= SIZE14) {
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return 13;
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} else if (size <= SIZE15) {
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return 14;
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} else if (size <= SIZE16) {
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return 15;
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} else if (size <= SIZE17) {
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return 16;
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} else {
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return 17;
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}
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}
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/*
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* insert_list - 将free block插入到相应大小的free list中, 插入位置为表头
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*/
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void insert_list(void *bp)
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{
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int index;
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size_t size;
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size = GET_SIZE(HDRP(bp));
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index = getListOffset(size);
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if (GET_PTR(heap_listp + WSIZE * index) == NULL) {
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PUT_PTR(heap_listp + WSIZE * index, bp);
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PUT_PTR(bp, NULL);
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PUT_PTR((unsigned int *)bp + 1, NULL);
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} else {
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PUT_PTR(bp, GET_PTR(heap_listp + WSIZE * index));
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PUT_PTR(GET_PTR(heap_listp + WSIZE * index) + 1, bp); /* 修改前一个位置 */
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PUT_PTR((unsigned int *)bp + 1, NULL);
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PUT_PTR(heap_listp + WSIZE * index, bp);
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}
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}
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/*
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* delete_list - 删除链表结点
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*/
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void delete_list(void *bp)
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{
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int index;
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size_t size;
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size = GET_SIZE(HDRP(bp));
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index = getListOffset(size);
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if (GET_PTR(bp) == NULL && GET_PTR((unsigned int *)bp + 1) == NULL) {
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/* 链表中唯一结点 */
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PUT_PTR(heap_listp + WSIZE * index, NULL);
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} else if (GET_PTR(bp) == NULL && GET_PTR((unsigned int *)bp + 1) != NULL) {
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/* 链表中最后一个结点, 不是唯一一个 */
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PUT_PTR(GET_PTR((unsigned int *)bp + 1), NULL);
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} else if (GET_PTR(bp) != NULL && GET_PTR((unsigned int *)bp + 1) == NULL){
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/* 链表中第一个结点, 不是唯一一个 */
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PUT_PTR(heap_listp + WSIZE * index, GET_PTR(bp));
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PUT_PTR(GET_PTR(bp) + 1, NULL);
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} else if (GET_PTR(bp) != NULL && GET_PTR((unsigned int *)bp + 1) != NULL) {
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/* 链表中的中间结点 */
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PUT_PTR(GET_PTR((unsigned int *)bp + 1), GET_PTR(bp));
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PUT_PTR(GET_PTR(bp) + 1, GET_PTR((unsigned int*)bp + 1));
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}
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}
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/*
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* find_fit - Search the free list for a fit
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*/
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void *find_fit(size_t asize)
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{
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int index;
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index = getListOffset(asize);
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unsigned int *ptr;
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/* 小的class内找不到就到大的class内找 */
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while (index < 18) {
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ptr = GET_PTR(heap_listp + 4 * index);
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while (ptr != NULL) {
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if (GET_SIZE(HDRP(ptr)) >= asize) {
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return (void *)ptr;
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}
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ptr = GET_PTR(ptr);
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}
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index++;
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}
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return NULL;
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}
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/*
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* place - place the requested block at the beginning of the free block
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*/
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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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delete_list(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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insert_list(bp);
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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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/*
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* mm_free - Freeing a block.
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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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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 - 直接用malloc和free组合实现
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*/
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void *mm_realloc(void *ptr, size_t size)
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{
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size_t asize;
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void *oldptr = ptr;
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void *newptr;
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/* free */
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if (0 == size) {
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free(oldptr);
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return NULL;
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}
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if (size <= DSIZE) {
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asize = 2 * DSIZE;
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} else {
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asize = DSIZE * ((size + (DSIZE) + (DSIZE - 1)) / DSIZE);
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}
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if (asize == GET_SIZE(HDRP(oldptr))) {
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return oldptr;
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}
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/* 缩小空间 */
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if (asize < GET_SIZE(HDRP(oldptr))) {
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newptr = mm_malloc(size);
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memmove(newptr, oldptr, size);
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mm_free(oldptr);
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return newptr;
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}
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newptr = mm_malloc(size);
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if (NULL == newptr)
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return NULL;
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memmove(newptr, oldptr, size);
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mm_free(oldptr);
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return newptr;
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}
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