Man page 9 : __bitmap_parse

__bitmap_parse - convert an ASCII hex string into a bitmap.

int __bitmap_parse(const char *  buf , unsigned int  buflen , int  is_user , unsigned long *  maskp , int  nmaskbits );

buf
    pointer to buffer containing string.

buflen
    buffer size in bytes. If string is smaller than this then it must be terminated with a \0.

is_user
    location of buffer, 0 indicates kernel space

maskp
    pointer to bitmap array that will contain result.

nmaskbits
    size of bitmap, in bits.

Commas group hex digits into chunks. Each chunk defines exactly 32 bits of the resultant bitmask. No chunk may specify a value larger than 32 bits (-EOVERFLOW), and if a chunk specifies a smaller value then leading 0-bits are prepended. -EINVAL is returned for illegal characters and for grouping errors such as « 1,,5 », « ,44 », « , » and "". Leading and trailing whitespace accepted, but not embedded whitespace.