Line data    Source code

       1             : #include <linux/export.h>
       2             : #include <linux/bug.h>
       3             : #include <linux/bitmap.h>
       4             : 
       5             : /**
       6             :  * memweight - count the total number of bits set in memory area
       7             :  * @ptr: pointer to the start of the area
       8             :  * @bytes: the size of the area
       9             :  */
      10           0 : size_t memweight(const void *ptr, size_t bytes)
      11             : {
      12             :         size_t ret = 0;
      13             :         size_t longs;
      14             :         const unsigned char *bitmap = ptr;
      15             : 
      16           0 :         for (; bytes > 0 && ((unsigned long)bitmap) % sizeof(long);
      17           0 :                         bytes--, bitmap++)
      18           0 :                 ret += hweight8(*bitmap);
      19             : 
      20           0 :         longs = bytes / sizeof(long);
      21           0 :         if (longs) {
      22             :                 BUG_ON(longs >= INT_MAX / BITS_PER_LONG);
      23           0 :                 ret += bitmap_weight((unsigned long *)bitmap,
      24             :                                 longs * BITS_PER_LONG);
      25           0 :                 bytes -= longs * sizeof(long);
      26           0 :                 bitmap += longs * sizeof(long);
      27             :         }
      28             :         /*
      29             :          * The reason that this last loop is distinct from the preceding
      30             :          * bitmap_weight() call is to compute 1-bits in the last region smaller
      31             :          * than sizeof(long) properly on big-endian systems.
      32             :          */
      33           0 :         for (; bytes > 0; bytes--, bitmap++)
      34           0 :                 ret += hweight8(*bitmap);
      35             : 
      36           0 :         return ret;
      37             : }
      38             : EXPORT_SYMBOL(memweight);