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1// SPDX-License-Identifier: GPL-2.02#include <linux/export.h>3#include <linux/bug.h>4#include <linux/bitmap.h>5 6/**7 * memweight - count the total number of bits set in memory area8 * @ptr: pointer to the start of the area9 * @bytes: the size of the area10 */11size_t memweight(const void *ptr, size_t bytes)12{13 size_t ret = 0;14 size_t longs;15 const unsigned char *bitmap = ptr;16 17 for (; bytes > 0 && ((unsigned long)bitmap) % sizeof(long);18 bytes--, bitmap++)19 ret += hweight8(*bitmap);20 21 longs = bytes / sizeof(long);22 if (longs) {23 BUG_ON(longs >= INT_MAX / BITS_PER_LONG);24 ret += bitmap_weight((unsigned long *)bitmap,25 longs * BITS_PER_LONG);26 bytes -= longs * sizeof(long);27 bitmap += longs * sizeof(long);28 }29 /*30 * The reason that this last loop is distinct from the preceding31 * bitmap_weight() call is to compute 1-bits in the last region smaller32 * than sizeof(long) properly on big-endian systems.33 */34 for (; bytes > 0; bytes--, bitmap++)35 ret += hweight8(*bitmap);36 37 return ret;38}39EXPORT_SYMBOL(memweight);40