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Unformatted text preview: ader and footer Header and footer Header and footer Header and footer Minimum block size (bytes) 12 8 16 8 B.10. VIRTUAL MEMORY Problem 10.8 Solution: [Pg. 543] 733 There is nothing very tricky here. But the solution requires you to understand how the rest of our simple implicit-list allocator works and how to manipulate and traverse blocks. code/vm/malloc.c 1 2 3 4 5 6 7 8 9 10 11 12 static void *find_fit(size_t asize) { void *bp; /* first fit search */ 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 */ } code/vm/malloc.c Problem 10.9 Solution: [Pg. 543] The is another warm-up exercise to help you become familiar with allocators. Notice that for this allocator the minimum block size is 16 bytes. If the remainder of the block after splitting would be greater than or equal to the minimum block size, then we go ahead and split the block (lines 6 to 10). The only tricky part here is to realize that you need to place the new allocated block (lines 6 and 7) before moving to the next block (line 8). code/vm/malloc.c 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 static void place(void *bp, size_t asize) { size_t csize = GET_SIZE(HDRP(bp)); if ((csize - asize) >= (DSIZE + OVERHEAD)) { 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...
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This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.

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