490 lines
12 KiB
C
490 lines
12 KiB
C
/*
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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/osdep.h"
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#include "qemu/bitops.h"
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#include "qemu/bitmap.h"
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#include "qemu/atomic.h"
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/*
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* bitmaps provide an array of bits, implemented using an
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* array of unsigned longs. The number of valid bits in a
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* given bitmap does _not_ need to be an exact multiple of
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* BITS_PER_LONG.
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*
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* The possible unused bits in the last, partially used word
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* of a bitmap are 'don't care'. The implementation makes
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* no particular effort to keep them zero. It ensures that
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* their value will not affect the results of any operation.
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* The bitmap operations that return Boolean (bitmap_empty,
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* for example) or scalar (bitmap_weight, for example) results
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* carefully filter out these unused bits from impacting their
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* results.
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*
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* These operations actually hold to a slightly stronger rule:
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* if you don't input any bitmaps to these ops that have some
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* unused bits set, then they won't output any set unused bits
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* in output bitmaps.
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*
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* The byte ordering of bitmaps is more natural on little
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* endian architectures.
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*/
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int slow_bitmap_empty(const unsigned long *bitmap, long bits)
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{
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long k, lim = bits/BITS_PER_LONG;
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for (k = 0; k < lim; ++k) {
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if (bitmap[k]) {
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return 0;
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}
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}
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if (bits % BITS_PER_LONG) {
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if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits)) {
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return 0;
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}
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}
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return 1;
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}
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int slow_bitmap_full(const unsigned long *bitmap, long bits)
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{
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long k, lim = bits/BITS_PER_LONG;
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for (k = 0; k < lim; ++k) {
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if (~bitmap[k]) {
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return 0;
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}
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}
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if (bits % BITS_PER_LONG) {
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if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits)) {
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return 0;
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}
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}
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return 1;
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}
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int slow_bitmap_equal(const unsigned long *bitmap1,
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const unsigned long *bitmap2, long bits)
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{
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long k, lim = bits/BITS_PER_LONG;
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for (k = 0; k < lim; ++k) {
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if (bitmap1[k] != bitmap2[k]) {
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return 0;
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}
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}
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if (bits % BITS_PER_LONG) {
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if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) {
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return 0;
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}
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}
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return 1;
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}
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void slow_bitmap_complement(unsigned long *dst, const unsigned long *src,
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long bits)
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{
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long k, lim = bits/BITS_PER_LONG;
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for (k = 0; k < lim; ++k) {
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dst[k] = ~src[k];
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}
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if (bits % BITS_PER_LONG) {
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dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);
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}
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}
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int slow_bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
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const unsigned long *bitmap2, long bits)
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{
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long k;
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long nr = BITS_TO_LONGS(bits);
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unsigned long result = 0;
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for (k = 0; k < nr; k++) {
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result |= (dst[k] = bitmap1[k] & bitmap2[k]);
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}
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return result != 0;
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}
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void slow_bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
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const unsigned long *bitmap2, long bits)
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{
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long k;
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long nr = BITS_TO_LONGS(bits);
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for (k = 0; k < nr; k++) {
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dst[k] = bitmap1[k] | bitmap2[k];
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}
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}
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void slow_bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
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const unsigned long *bitmap2, long bits)
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{
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long k;
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long nr = BITS_TO_LONGS(bits);
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for (k = 0; k < nr; k++) {
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dst[k] = bitmap1[k] ^ bitmap2[k];
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}
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}
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int slow_bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
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const unsigned long *bitmap2, long bits)
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{
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long k;
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long nr = BITS_TO_LONGS(bits);
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unsigned long result = 0;
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for (k = 0; k < nr; k++) {
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result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
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}
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return result != 0;
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}
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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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assert(start >= 0 && nr >= 0);
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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_set_atomic(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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assert(start >= 0 && nr >= 0);
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/* First word */
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if (nr - bits_to_set > 0) {
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qatomic_or(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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/* Full words */
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if (bits_to_set == BITS_PER_LONG) {
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while (nr >= BITS_PER_LONG) {
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*p = ~0UL;
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nr -= BITS_PER_LONG;
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p++;
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}
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}
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/* Last word */
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if (nr) {
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mask_to_set &= BITMAP_LAST_WORD_MASK(size);
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qatomic_or(p, mask_to_set);
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} else {
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/* If we avoided the full barrier in qatomic_or(), issue a
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* barrier to account for the assignments in the while loop.
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*/
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smp_mb();
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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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assert(start >= 0 && nr >= 0);
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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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bool bitmap_test_and_clear_atomic(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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unsigned long dirty = 0;
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unsigned long old_bits;
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assert(start >= 0 && nr >= 0);
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/* First word */
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if (nr - bits_to_clear > 0) {
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old_bits = qatomic_fetch_and(p, ~mask_to_clear);
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dirty |= old_bits & 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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/* Full words */
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if (bits_to_clear == BITS_PER_LONG) {
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while (nr >= BITS_PER_LONG) {
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if (*p) {
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old_bits = qatomic_xchg(p, 0);
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dirty |= old_bits;
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}
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nr -= BITS_PER_LONG;
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p++;
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}
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}
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/* Last word */
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if (nr) {
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mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
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old_bits = qatomic_fetch_and(p, ~mask_to_clear);
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dirty |= old_bits & mask_to_clear;
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} else {
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if (!dirty) {
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smp_mb();
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}
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}
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return dirty != 0;
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}
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void bitmap_copy_and_clear_atomic(unsigned long *dst, unsigned long *src,
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long nr)
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{
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while (nr > 0) {
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*dst = qatomic_xchg(src, 0);
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dst++;
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src++;
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nr -= BITS_PER_LONG;
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}
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}
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#define ALIGN_MASK(x,mask) (((x)+(mask))&~(mask))
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/**
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* bitmap_find_next_zero_area - find a contiguous aligned zero area
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* @map: The address to base the search on
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* @size: The bitmap size in bits
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* @start: The bitnumber to start searching at
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* @nr: The number of zeroed bits we're looking for
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* @align_mask: Alignment mask for zero area
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*
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* The @align_mask should be one less than a power of 2; the effect is that
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* the bit offset of all zero areas this function finds is multiples of that
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* power of 2. A @align_mask of 0 means no alignment is required.
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*/
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unsigned long bitmap_find_next_zero_area(unsigned long *map,
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unsigned long size,
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unsigned long start,
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unsigned long nr,
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unsigned long align_mask)
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{
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unsigned long index, end, i;
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again:
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index = find_next_zero_bit(map, size, start);
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/* Align allocation */
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index = ALIGN_MASK(index, align_mask);
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end = index + nr;
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if (end > size) {
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return end;
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}
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i = find_next_bit(map, end, index);
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if (i < end) {
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start = i + 1;
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goto again;
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}
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return index;
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}
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int slow_bitmap_intersects(const unsigned long *bitmap1,
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const unsigned long *bitmap2, long bits)
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{
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long k, lim = bits/BITS_PER_LONG;
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for (k = 0; k < lim; ++k) {
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if (bitmap1[k] & bitmap2[k]) {
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return 1;
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}
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}
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if (bits % BITS_PER_LONG) {
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if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) {
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return 1;
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}
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}
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return 0;
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}
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long slow_bitmap_count_one(const unsigned long *bitmap, long nbits)
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{
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long k, lim = nbits / BITS_PER_LONG, result = 0;
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for (k = 0; k < lim; k++) {
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result += ctpopl(bitmap[k]);
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}
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if (nbits % BITS_PER_LONG) {
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result += ctpopl(bitmap[k] & BITMAP_LAST_WORD_MASK(nbits));
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}
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return result;
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}
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static void bitmap_to_from_le(unsigned long *dst,
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const unsigned long *src, long nbits)
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{
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long len = BITS_TO_LONGS(nbits);
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#if HOST_BIG_ENDIAN
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long index;
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for (index = 0; index < len; index++) {
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# if HOST_LONG_BITS == 64
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dst[index] = bswap64(src[index]);
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# else
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dst[index] = bswap32(src[index]);
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# endif
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}
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#else
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memcpy(dst, src, len * sizeof(unsigned long));
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#endif
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}
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void bitmap_from_le(unsigned long *dst, const unsigned long *src,
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long nbits)
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{
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bitmap_to_from_le(dst, src, nbits);
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}
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void bitmap_to_le(unsigned long *dst, const unsigned long *src,
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long nbits)
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{
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bitmap_to_from_le(dst, src, nbits);
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}
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/*
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* Copy "src" bitmap with a positive offset and put it into the "dst"
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* bitmap. The caller needs to make sure the bitmap size of "src"
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* is bigger than (shift + nbits).
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*/
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void bitmap_copy_with_src_offset(unsigned long *dst, const unsigned long *src,
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unsigned long shift, unsigned long nbits)
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{
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unsigned long left_mask, right_mask, last_mask;
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/* Proper shift src pointer to the first word to copy from */
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src += BIT_WORD(shift);
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shift %= BITS_PER_LONG;
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if (!shift) {
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/* Fast path */
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bitmap_copy(dst, src, nbits);
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return;
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}
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right_mask = (1ul << shift) - 1;
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left_mask = ~right_mask;
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while (nbits >= BITS_PER_LONG) {
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*dst = (*src & left_mask) >> shift;
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*dst |= (src[1] & right_mask) << (BITS_PER_LONG - shift);
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dst++;
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src++;
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nbits -= BITS_PER_LONG;
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}
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if (nbits > BITS_PER_LONG - shift) {
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*dst = (*src & left_mask) >> shift;
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nbits -= BITS_PER_LONG - shift;
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last_mask = (1ul << nbits) - 1;
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*dst |= (src[1] & last_mask) << (BITS_PER_LONG - shift);
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} else if (nbits) {
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last_mask = (1ul << nbits) - 1;
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*dst = (*src >> shift) & last_mask;
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}
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}
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/*
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* Copy "src" bitmap into the "dst" bitmap with an offset in the
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* "dst". The caller needs to make sure the bitmap size of "dst" is
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* bigger than (shift + nbits).
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*/
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void bitmap_copy_with_dst_offset(unsigned long *dst, const unsigned long *src,
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unsigned long shift, unsigned long nbits)
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{
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unsigned long left_mask, right_mask, last_mask;
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/* Proper shift dst pointer to the first word to copy from */
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dst += BIT_WORD(shift);
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shift %= BITS_PER_LONG;
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if (!shift) {
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/* Fast path */
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bitmap_copy(dst, src, nbits);
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return;
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}
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right_mask = (1ul << (BITS_PER_LONG - shift)) - 1;
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left_mask = ~right_mask;
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*dst &= (1ul << shift) - 1;
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while (nbits >= BITS_PER_LONG) {
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*dst |= (*src & right_mask) << shift;
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dst[1] = (*src & left_mask) >> (BITS_PER_LONG - shift);
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dst++;
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src++;
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nbits -= BITS_PER_LONG;
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}
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if (nbits > BITS_PER_LONG - shift) {
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*dst |= (*src & right_mask) << shift;
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nbits -= BITS_PER_LONG - shift;
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last_mask = ((1ul << nbits) - 1) << (BITS_PER_LONG - shift);
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dst[1] = (*src & last_mask) >> (BITS_PER_LONG - shift);
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} else if (nbits) {
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last_mask = (1ul << nbits) - 1;
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*dst |= (*src & last_mask) << shift;
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}
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}
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