This macro iterates for each group of bits (port word) with set bits, within a bitmap memory region. For each iteration, "port_word" is set to the found port word index, "word_index" is set to the word index of the bitmap containing the found port word, and "word_offset" is set to the bit offset of the found port word within the respective bitmap word.
Cc: Arnd Bergmann <[email protected]> Signed-off-by: William Breathitt Gray <[email protected]> --- include/asm-generic/bitops/find.h | 24 ++++++++++++++++++++++++ include/linux/bitops.h | 9 +++++++++ lib/find_bit.c | 28 ++++++++++++++++++++++++++++ 3 files changed, 61 insertions(+) diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h index 8a1ee10014de..b24f3f92642b 100644 --- a/include/asm-generic/bitops/find.h +++ b/include/asm-generic/bitops/find.h @@ -80,4 +80,28 @@ extern unsigned long find_first_zero_bit(const unsigned long *addr, #endif /* CONFIG_GENERIC_FIND_FIRST_BIT */ +/** + * find_next_port_word - find next port word with set bits in a memory region + * @word_index: location to store bitmap word index of found port word + * @word_offset: bits offset of the found port word in respective bitmap word + * @bits: address to base the search on + * @size: bitmap size in number of ports + * @offset: port word index to start searching at + * @port_size: port word size in bits + * + * Returns the port index for the next port word with set bits; the respective + * bitmap word index is stored at the location pointed by @word_index, and the + * bits offset of the found port word within the respective bitmap word is + * stored at the location pointed by @word_offset. If no bits are set, returns + * @size. + */ +size_t find_next_port_word(size_t *const word_index, + unsigned int *const word_offset, + const unsigned long *const bits, const size_t size, + const size_t offset, const unsigned int port_size); + +#define find_first_port_word(word_index, word_offset, bits, size, port_size) \ + find_next_port_word((word_index), (word_offset), (bits), (size), 0, \ + (port_size)) + #endif /*_ASM_GENERIC_BITOPS_FIND_H_ */ diff --git a/include/linux/bitops.h b/include/linux/bitops.h index 4cac4e1a72ff..c3b7caf4ad2d 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -59,6 +59,15 @@ extern unsigned long __sw_hweight64(__u64 w); (bit) < (size); \ (bit) = find_next_zero_bit((addr), (size), (bit) + 1)) +#define for_each_set_port_word(port_word, word_index, word_offset, bits, size, \ + port_size) \ + for ((port_word) = find_first_port_word(&(word_index), &(word_offset), \ + (bits), (size), (port_size)); \ + (port_word) < (size); \ + (port_word) = find_next_port_word(&(word_index), &(word_offset), \ + (bits), (size), (port_word) + 1, \ + (port_size))) + static inline int get_bitmask_order(unsigned int count) { int order; diff --git a/lib/find_bit.c b/lib/find_bit.c index ee3df93ba69a..628c94d63d6b 100644 --- a/lib/find_bit.c +++ b/lib/find_bit.c @@ -20,6 +20,7 @@ #include <linux/bitmap.h> #include <linux/export.h> #include <linux/kernel.h> +#include <linux/types.h> #if !defined(find_next_bit) || !defined(find_next_zero_bit) || \ !defined(find_next_and_bit) @@ -218,3 +219,30 @@ EXPORT_SYMBOL(find_next_bit_le); #endif #endif /* __BIG_ENDIAN */ + +size_t find_next_port_word(size_t *const word_index, + unsigned int *const word_offset, + const unsigned long *const bits, const size_t size, + const size_t offset, const unsigned int port_size) +{ + size_t i; + unsigned int bits_offset; + unsigned long word_mask; + const unsigned long port_mask = GENMASK(port_size - 1, 0); + + for (i = offset; i < size; i++) { + bits_offset = i * port_size; + + *word_index = BIT_WORD(bits_offset); + *word_offset = bits_offset % BITS_PER_LONG; + + word_mask = bits[*word_index] & (port_mask << *word_offset); + if (!word_mask) + continue; + + return i; + } + + return size; +} +EXPORT_SYMBOL(find_next_port_word); -- 2.17.0
