Branch data     Line data    Source code

       1                 :            : // SPDX-License-Identifier: GPL-2.0
       2                 :            : #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 area
       8                 :            :  * @ptr: pointer to the start of the area
       9                 :            :  * @bytes: the size of the area
      10                 :            :  */
      11                 :          0 : size_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   [ #  #  #  # ]:          0 :         for (; bytes > 0 && ((unsigned long)bitmap) % sizeof(long);
      18                 :          0 :                         bytes--, bitmap++)
      19         [ #  # ]:          0 :                 ret += hweight8(*bitmap);
      20                 :            : 
      21                 :          0 :         longs = bytes / sizeof(long);
      22         [ #  # ]:          0 :         if (longs) {
      23         [ #  # ]:          0 :                 BUG_ON(longs >= INT_MAX / BITS_PER_LONG);
      24                 :          0 :                 ret += bitmap_weight((unsigned long *)bitmap,
      25                 :            :                                 longs * BITS_PER_LONG);
      26                 :          0 :                 bytes -= longs * sizeof(long);
      27                 :          0 :                 bitmap += longs * sizeof(long);
      28                 :            :         }
      29                 :            :         /*
      30                 :            :          * The reason that this last loop is distinct from the preceding
      31                 :            :          * bitmap_weight() call is to compute 1-bits in the last region smaller
      32                 :            :          * than sizeof(long) properly on big-endian systems.
      33                 :            :          */
      34         [ #  # ]:          0 :         for (; bytes > 0; bytes--, bitmap++)
      35         [ #  # ]:          0 :                 ret += hweight8(*bitmap);
      36                 :            : 
      37                 :          0 :         return ret;
      38                 :            : }
      39                 :            : EXPORT_SYMBOL(memweight);