56 lines
1.4 KiB
C
56 lines
1.4 KiB
C
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/*
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* Bitmap Module
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*
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* Stolen from linux/src/lib/bitmap.c
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*
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* Copyright (C) 2010 Corentin Chary
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*
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* This source code is licensed under the GNU General Public License,
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* Version 2.
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*/
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#include "qemu/bitops.h"
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#include "qemu/bitmap.h"
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#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG))
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void bitmap_set(unsigned long *map, long start, long nr)
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{
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unsigned long *p = map + BIT_WORD(start);
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const long size = start + nr;
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int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
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unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
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while (nr - bits_to_set >= 0) {
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*p |= mask_to_set;
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nr -= bits_to_set;
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bits_to_set = BITS_PER_LONG;
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mask_to_set = ~0UL;
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p++;
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}
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if (nr) {
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mask_to_set &= BITMAP_LAST_WORD_MASK(size);
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*p |= mask_to_set;
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}
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}
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void bitmap_clear(unsigned long *map, long start, long nr)
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{
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unsigned long *p = map + BIT_WORD(start);
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const long size = start + nr;
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int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
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unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
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while (nr - bits_to_clear >= 0) {
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*p &= ~mask_to_clear;
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nr -= bits_to_clear;
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bits_to_clear = BITS_PER_LONG;
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mask_to_clear = ~0UL;
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p++;
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}
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if (nr) {
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mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
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*p &= ~mask_to_clear;
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}
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}
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