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/*
* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
* Copyright (C) 2008 IBM Corporation
* Written by Rusty Russell <rusty@rustcorp.com.au>
* (Inspired by David Howell's find_next_bit implementation)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include "qemu/bitops.h"
#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
/*
* Find the next set bit in a memory region.
*/
unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
unsigned long offset)
{
const unsigned long *p = addr + BITOP_WORD(offset);
unsigned long result = offset & ~(BITS_PER_LONG-1);
unsigned long tmp;
if (offset >= size) {
return size;
}
size -= result;
offset %= BITS_PER_LONG;
if (offset) {
tmp = *(p++);
tmp &= (~0UL << offset);
if (size < BITS_PER_LONG) {
goto found_first;
}
if (tmp) {
goto found_middle;
}
size -= BITS_PER_LONG;
result += BITS_PER_LONG;
}
while (size & ~(BITS_PER_LONG-1)) {
if ((tmp = *(p++))) {
goto found_middle;
}
result += BITS_PER_LONG;
size -= BITS_PER_LONG;
}
if (!size) {
return result;
}
tmp = *p;
found_first:
tmp &= (~0UL >> (BITS_PER_LONG - size));
if (tmp == 0UL) { /* Are any bits set? */
return result + size; /* Nope. */
}
found_middle:
return result + ctzl(tmp);
}
/*
* This implementation of find_{first,next}_zero_bit was stolen from
* Linus' asm-alpha/bitops.h.
*/
unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
unsigned long offset)
{
const unsigned long *p = addr + BITOP_WORD(offset);
unsigned long result = offset & ~(BITS_PER_LONG-1);
unsigned long tmp;
if (offset >= size) {
return size;
}
size -= result;
offset %= BITS_PER_LONG;
if (offset) {
tmp = *(p++);
tmp |= ~0UL >> (BITS_PER_LONG - offset);
if (size < BITS_PER_LONG) {
goto found_first;
}
if (~tmp) {
goto found_middle;
}
size -= BITS_PER_LONG;
result += BITS_PER_LONG;
}
while (size & ~(BITS_PER_LONG-1)) {
if (~(tmp = *(p++))) {
goto found_middle;
}
result += BITS_PER_LONG;
size -= BITS_PER_LONG;
}
if (!size) {
return result;
}
tmp = *p;
found_first:
tmp |= ~0UL << size;
if (tmp == ~0UL) { /* Are any bits zero? */
return result + size; /* Nope. */
}
found_middle:
return result + bitops_ctol(tmp);
}
unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
{
unsigned long words;
unsigned long tmp;
/* Start at final word. */
words = size / BITS_PER_LONG;
/* Partial final word? */
if (size & (BITS_PER_LONG-1)) {
tmp = (addr[words] & (~0UL >> (BITS_PER_LONG
- (size & (BITS_PER_LONG-1)))));
if (tmp) {
goto found;
}
}
while (words) {
tmp = addr[--words];
if (tmp) {
found:
return words * BITS_PER_LONG + BITS_PER_LONG - 1 - clzl(tmp);
}
}
/* Not found */
return size;
}
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