/*
* Bitmap Module
*
* Stolen from linux/src/lib/bitmap.c
*
* Copyright (C) 2010 Corentin Chary
*
* This source code is licensed under the GNU General Public License,
* Version 2.
*/
#include "bitops.h"
#include "bitmap.h"
/*
* bitmaps provide an array of bits, implemented using an an
* array of unsigned longs. The number of valid bits in a
* given bitmap does _not_ need to be an exact multiple of
* BITS_PER_LONG.
*
* The possible unused bits in the last, partially used word
* of a bitmap are 'don't care'. The implementation makes
* no particular effort to keep them zero. It ensures that
* their value will not affect the results of any operation.
* The bitmap operations that return Boolean (bitmap_empty,
* for example) or scalar (bitmap_weight, for example) results
* carefully filter out these unused bits from impacting their
* results.
*
* These operations actually hold to a slightly stronger rule:
* if you don't input any bitmaps to these ops that have some
* unused bits set, then they won't output any set unused bits
* in output bitmaps.
*
* The byte ordering of bitmaps is more natural on little
* endian architectures.
*/
int slow_bitmap_empty(const unsigned long *bitmap, int bits)
{
int k, lim = bits/BITS_PER_LONG;
for (k = 0; k < lim; ++k) {
if (bitmap[k]) {
return 0;
}
}
if (bits % BITS_PER_LONG) {
if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits)) {
return 0;
}
}
return 1;
}
int slow_bitmap_full(const unsigned long *bitmap, int bits)
{
int k, lim = bits/BITS_PER_LONG;
for (k = 0; k < lim; ++k) {
if (~bitmap[k]) {
return 0;
}
}
if (bits % BITS_PER_LONG) {
if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits)) {
return 0;
}
}
return 1;
}
int slow_bitmap_equal(const unsigned long *bitmap1,
const unsigned long *bitmap2, int bits)
{
int k, lim = bits/BITS_PER_LONG;
for (k = 0; k < lim; ++k) {
if (bitmap1[k] != bitmap2[k]) {
return 0;
}
}
if (bits % BITS_PER_LONG) {
if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) {
return 0;
}
}
return 1;
}
void slow_bitmap_complement(unsigned long *dst, const unsigned long *src,
int bits)
{
int k, lim = bits/BITS_PER_LONG;
for (k = 0; k < lim; ++k) {
dst[k] = ~src[k];
}
if (bits % BITS_PER_LONG) {
dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);
}
}
int slow_bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, int bits)
{
int k;
int nr = BITS_TO_LONGS(bits);
unsigned long result = 0;
for (k = 0; k < nr; k++) {
result |= (dst[k] = bitmap1[k] & bitmap2[k]);
}
return result != 0;
}
void slow_bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, int bits)
{
int k;
int nr = BITS_TO_LONGS(bits);
for (k = 0; k < nr; k++) {
dst[k] = bitmap1[k] | bitmap2[k];
}
}
void slow_bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, int bits)
{
int k;
int nr = BITS_TO_LONGS(bits);
for (k = 0; k < nr; k++) {
dst[k] = bitmap1[k] ^ bitmap2[k];
}
}
int slow_bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, int bits)
{
int k;
int nr = BITS_TO_LONGS(bits);
unsigned long result = 0;
for (k = 0; k < nr; k++) {
result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
}
return result != 0;
}
#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG))
void bitmap_set(unsigned long *map, int start, int nr)
{
unsigned long *p = map + BIT_WORD(start);
const int size = start + nr;
int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
while (nr - bits_to_set >= 0) {
*p |= mask_to_set;
nr -= bits_to_set;
bits_to_set = BITS_PER_LONG;
mask_to_set = ~0UL;
p++;
}
if (nr) {
mask_to_set &= BITMAP_LAST_WORD_MASK(size);
*p |= mask_to_set;
}
}
void bitmap_clear(unsigned long *map, int start, int nr)
{
unsigned long *p = map + BIT_WORD(start);
const int size = start + nr;
int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
while (nr - bits_to_clear >= 0) {
*p &= ~mask_to_clear;
nr -= bits_to_clear;
bits_to_clear = BITS_PER_LONG;
mask_to_clear = ~0UL;
p++;
}
if (nr) {
mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
*p &= ~mask_to_clear;
}
}
#define ALIGN_MASK(x,mask) (((x)+(mask))&~(mask))
/**
* bitmap_find_next_zero_area - find a contiguous aligned zero area
* @map: The address to base the search on
* @size: The bitmap size in bits
* @start: The bitnumber to start searching at
* @nr: The number of zeroed bits we're looking for
* @align_mask: Alignment mask for zero area
*
* The @align_mask should be one less than a power of 2; the effect is that
* the bit offset of all zero areas this function finds is multiples of that
* power of 2. A @align_mask of 0 means no alignment is required.
*/
unsigned long bitmap_find_next_zero_area(unsigned long *map,
unsigned long size,
unsigned long start,
unsigned int nr,
unsigned long align_mask)
{
unsigned long index, end, i;
again:
index = find_next_zero_bit(map, size, start);
/* Align allocation */
index = ALIGN_MASK(index, align_mask);
end = index + nr;
if (end > size) {
return end;
}
i = find_next_bit(map, end, index);
if (i < end) {
start = i + 1;
goto again;
}
return index;
}
int slow_bitmap_intersects(const unsigned long *bitmap1,
const unsigned long *bitmap2, int bits)
{
int k, lim = bits/BITS_PER_LONG;
for (k = 0; k < lim; ++k) {
if (bitmap1[k] & bitmap2[k]) {
return 1;
}
}
if (bits % BITS_PER_LONG) {
if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) {
return 1;
}
}
return 0;
}
