#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);