#include <linux/export.h>#include <linux/bug.h>#include <linux/bitmap.h>/** * memweight - count the total number of bits set in memory area * @ptr: pointer to the start of the area * @bytes: the size of the area */size_t memweight(const void *ptr, size_t bytes){ size_t ret = 0; size_t longs; const unsigned char *bitmap = ptr; for (; bytes > 0 && ((unsigned long)bitmap) % sizeof(long); bytes--, bitmap++) ret += hweight8(*bitmap); longs = bytes / sizeof(long); if (longs) { BUG_ON(longs >= INT_MAX / BITS_PER_LONG); ret += bitmap_weight((unsigned long *)bitmap, longs * BITS_PER_LONG); bytes -= longs * sizeof(long); bitmap += longs * sizeof(long); } /* * The reason that this last loop is distinct from the preceding * bitmap_weight() call is to compute 1-bits in the last region smaller * than sizeof(long) properly on big-endian systems. */ for (; bytes > 0; bytes--, bitmap++) ret += hweight8(*bitmap); return ret;}EXPORT_SYMBOL(memweight);
#include <linux/export.h>
#include <linux/bug.h>
#include <linux/bitmap.h>
/**
* memweight - count the total number of bits set in memory area
* @ptr: pointer to the start of the area
* @bytes: the size of the area
*/
size_t memweight(const void *ptr, size_t bytes)
{
size_t ret = 0;
size_t longs;
const unsigned char *bitmap = ptr;
for (; bytes > 0 && ((unsigned long)bitmap) % sizeof(long);
bytes--, bitmap++)
ret += hweight8(*bitmap);
longs = bytes / sizeof(long);
if (longs) {
BUG_ON(longs >= INT_MAX / BITS_PER_LONG);
ret += bitmap_weight((unsigned long *)bitmap,
longs * BITS_PER_LONG);
bytes -= longs * sizeof(long);
bitmap += longs * sizeof(long);
}
/*
* The reason that this last loop is distinct from the preceding
* bitmap_weight() call is to compute 1-bits in the last region smaller
* than sizeof(long) properly on big-endian systems.
*/
for (; bytes > 0; bytes--, bitmap++)
ret += hweight8(*bitmap);
return ret;
}
EXPORT_SYMBOL(memweight);