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qemu-patch-raspberry4/include/qemu/bitmap.h
Stefan Hajnoczi 9f02cfc84b bitmap: add atomic set functions 
Use atomic_or() for atomic bitmaps where several threads may set bits at
the same time.  This avoids the race condition between threads loading
an element, bitwise ORing, and then storing the element.

When setting all bits in a word we can avoid atomic ops and instead just
use an smp_mb() at the end.

Most bitmap users don't need atomicity so introduce new functions.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <1417519399-3166-2-git-send-email-stefanha@redhat.com>
[Avoid barrier in the single word case, use full barrier instead of write.
 - Paolo]
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-06-05 17:10:00 +02:00

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/*
* Bitmap Module
*
* Copyright (C) 2010 Corentin Chary <corentin.chary@gmail.com>
*
* Mostly inspired by (stolen from) linux/bitmap.h and linux/bitops.h
*
* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
* See the COPYING.LIB file in the top-level directory.
*/
#ifndef BITMAP_H
#define BITMAP_H
#include <glib.h>
#include <string.h>
#include <stdlib.h>
#include "qemu/osdep.h"
#include "qemu/bitops.h"
/*
* The available bitmap operations and their rough meaning in the
* case that the bitmap is a single unsigned long are thus:
*
* Note that nbits should be always a compile time evaluable constant.
* Otherwise many inlines will generate horrible code.
*
* bitmap_zero(dst, nbits) *dst = 0UL
* bitmap_fill(dst, nbits) *dst = ~0UL
* bitmap_copy(dst, src, nbits) *dst = *src
* bitmap_and(dst, src1, src2, nbits) *dst = *src1 & *src2
* bitmap_or(dst, src1, src2, nbits) *dst = *src1 | *src2
* bitmap_xor(dst, src1, src2, nbits) *dst = *src1 ^ *src2
* bitmap_andnot(dst, src1, src2, nbits) *dst = *src1 & ~(*src2)
* bitmap_complement(dst, src, nbits) *dst = ~(*src)
* bitmap_equal(src1, src2, nbits) Are *src1 and *src2 equal?
* bitmap_intersects(src1, src2, nbits) Do *src1 and *src2 overlap?
* bitmap_empty(src, nbits) Are all bits zero in *src?
* bitmap_full(src, nbits) Are all bits set in *src?
* bitmap_set(dst, pos, nbits) Set specified bit area
* bitmap_set_atomic(dst, pos, nbits) Set specified bit area with atomic ops
* bitmap_clear(dst, pos, nbits) Clear specified bit area
* bitmap_find_next_zero_area(buf, len, pos, n, mask) Find bit free area
*/
/*
* Also the following operations apply to bitmaps.
*
* set_bit(bit, addr) *addr |= bit
* clear_bit(bit, addr) *addr &= ~bit
* change_bit(bit, addr) *addr ^= bit
* test_bit(bit, addr) Is bit set in *addr?
* test_and_set_bit(bit, addr) Set bit and return old value
* test_and_clear_bit(bit, addr) Clear bit and return old value
* test_and_change_bit(bit, addr) Change bit and return old value
* find_first_zero_bit(addr, nbits) Position first zero bit in *addr
* find_first_bit(addr, nbits) Position first set bit in *addr
* find_next_zero_bit(addr, nbits, bit) Position next zero bit in *addr >= bit
* find_next_bit(addr, nbits, bit) Position next set bit in *addr >= bit
*/
#define BITMAP_LAST_WORD_MASK(nbits) \
( \
((nbits) % BITS_PER_LONG) ? \
(1UL<<((nbits) % BITS_PER_LONG))-1 : ~0UL \
)
#define DECLARE_BITMAP(name,bits) \
unsigned long name[BITS_TO_LONGS(bits)]
#define small_nbits(nbits) \
((nbits) <= BITS_PER_LONG)
int slow_bitmap_empty(const unsigned long *bitmap, long bits);
int slow_bitmap_full(const unsigned long *bitmap, long bits);
int slow_bitmap_equal(const unsigned long *bitmap1,
const unsigned long *bitmap2, long bits);
void slow_bitmap_complement(unsigned long *dst, const unsigned long *src,
long bits);
void slow_bitmap_shift_right(unsigned long *dst,
const unsigned long *src, int shift, long bits);
void slow_bitmap_shift_left(unsigned long *dst,
const unsigned long *src, int shift, long bits);
int slow_bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, long bits);
void slow_bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, long bits);
void slow_bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, long bits);
int slow_bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, long bits);
int slow_bitmap_intersects(const unsigned long *bitmap1,
const unsigned long *bitmap2, long bits);
static inline unsigned long *bitmap_try_new(long nbits)
{
long len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
return g_try_malloc0(len);
}
static inline unsigned long *bitmap_new(long nbits)
{
unsigned long *ptr = bitmap_try_new(nbits);
if (ptr == NULL) {
abort();
}
return ptr;
}
static inline void bitmap_zero(unsigned long *dst, long nbits)
{
if (small_nbits(nbits)) {
*dst = 0UL;
} else {
long len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
memset(dst, 0, len);
}
}
static inline void bitmap_fill(unsigned long *dst, long nbits)
{
size_t nlongs = BITS_TO_LONGS(nbits);
if (!small_nbits(nbits)) {
long len = (nlongs - 1) * sizeof(unsigned long);
memset(dst, 0xff, len);
}
dst[nlongs - 1] = BITMAP_LAST_WORD_MASK(nbits);
}
static inline void bitmap_copy(unsigned long *dst, const unsigned long *src,
long nbits)
{
if (small_nbits(nbits)) {
*dst = *src;
} else {
long len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
memcpy(dst, src, len);
}
}
static inline int bitmap_and(unsigned long *dst, const unsigned long *src1,
const unsigned long *src2, long nbits)
{
if (small_nbits(nbits)) {
return (*dst = *src1 & *src2) != 0;
}
return slow_bitmap_and(dst, src1, src2, nbits);
}
static inline void bitmap_or(unsigned long *dst, const unsigned long *src1,
const unsigned long *src2, long nbits)
{
if (small_nbits(nbits)) {
*dst = *src1 | *src2;
} else {
slow_bitmap_or(dst, src1, src2, nbits);
}
}
static inline void bitmap_xor(unsigned long *dst, const unsigned long *src1,
const unsigned long *src2, long nbits)
{
if (small_nbits(nbits)) {
*dst = *src1 ^ *src2;
} else {
slow_bitmap_xor(dst, src1, src2, nbits);
}
}
static inline int bitmap_andnot(unsigned long *dst, const unsigned long *src1,
const unsigned long *src2, long nbits)
{
if (small_nbits(nbits)) {
return (*dst = *src1 & ~(*src2)) != 0;
}
return slow_bitmap_andnot(dst, src1, src2, nbits);
}
static inline void bitmap_complement(unsigned long *dst,
const unsigned long *src,
long nbits)
{
if (small_nbits(nbits)) {
*dst = ~(*src) & BITMAP_LAST_WORD_MASK(nbits);
} else {
slow_bitmap_complement(dst, src, nbits);
}
}
static inline int bitmap_equal(const unsigned long *src1,
const unsigned long *src2, long nbits)
{
if (small_nbits(nbits)) {
return ! ((*src1 ^ *src2) & BITMAP_LAST_WORD_MASK(nbits));
} else {
return slow_bitmap_equal(src1, src2, nbits);
}
}
static inline int bitmap_empty(const unsigned long *src, long nbits)
{
if (small_nbits(nbits)) {
return ! (*src & BITMAP_LAST_WORD_MASK(nbits));
} else {
return slow_bitmap_empty(src, nbits);
}
}
static inline int bitmap_full(const unsigned long *src, long nbits)
{
if (small_nbits(nbits)) {
return ! (~(*src) & BITMAP_LAST_WORD_MASK(nbits));
} else {
return slow_bitmap_full(src, nbits);
}
}
static inline int bitmap_intersects(const unsigned long *src1,
const unsigned long *src2, long nbits)
{
if (small_nbits(nbits)) {
return ((*src1 & *src2) & BITMAP_LAST_WORD_MASK(nbits)) != 0;
} else {
return slow_bitmap_intersects(src1, src2, nbits);
}
}
void bitmap_set(unsigned long *map, long i, long len);
void bitmap_set_atomic(unsigned long *map, long i, long len);
void bitmap_clear(unsigned long *map, long start, long nr);
unsigned long bitmap_find_next_zero_area(unsigned long *map,
unsigned long size,
unsigned long start,
unsigned long nr,
unsigned long align_mask);
static inline unsigned long *bitmap_zero_extend(unsigned long *old,
long old_nbits, long new_nbits)
{
long new_len = BITS_TO_LONGS(new_nbits) * sizeof(unsigned long);
unsigned long *new = g_realloc(old, new_len);
bitmap_clear(new, old_nbits, new_nbits - old_nbits);
return new;
}
#endif /* BITMAP_H */
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