On Mon, Mar 25, 2019 at 03:22:23PM +0900, William Breathitt Gray wrote: > This macro iterates for each 8-bit group of bits (clump) with set bits, > within a bitmap memory region. For each iteration, "start" is set to the > bit offset of the found clump, while the respective clump value is > stored to the location pointed by "clump". Additionally, the > bitmap_get_value8 and bitmap_set_value8 functions are introduced to > respectively get and set an 8-bit value in a bitmap memory region.
This seems to miss Randy's (IIRC) comment about too many const specifiers. > Suggested-by: Andy Shevchenko <[email protected]> > Suggested-by: Rasmus Villemoes <[email protected]> > Cc: Arnd Bergmann <[email protected]> > Acked-by: Andrew Morton <[email protected]> > Reviewed-by: Andy Shevchenko <[email protected]> > Reviewed-by: Linus Walleij <[email protected]> > Signed-off-by: William Breathitt Gray <[email protected]> > --- > include/asm-generic/bitops/find.h | 14 ++++++ > include/linux/bitops.h | 5 ++ > lib/find_bit.c | 81 +++++++++++++++++++++++++++++++ > 3 files changed, 100 insertions(+) > > diff --git a/include/asm-generic/bitops/find.h > b/include/asm-generic/bitops/find.h > index 8a1ee10014de..9a76adff59c6 100644 > --- a/include/asm-generic/bitops/find.h > +++ b/include/asm-generic/bitops/find.h > @@ -80,4 +80,18 @@ extern unsigned long find_first_zero_bit(const unsigned > long *addr, > > #endif /* CONFIG_GENERIC_FIND_FIRST_BIT */ > > +unsigned long bitmap_get_value8(const unsigned long *const bitmap, > + const unsigned int size, > + const unsigned int start); > + > +void bitmap_set_value8(unsigned long *const bitmap, const unsigned int size, > + const unsigned long value, const unsigned int start); > + > +unsigned int find_next_clump8(unsigned long *const clump, > + const unsigned long *const addr, > + unsigned int offset, const unsigned int size); > + > +#define find_first_clump8(clump, bits, size) \ > + find_next_clump8((clump), (bits), 0, (size)) > + > #endif /*_ASM_GENERIC_BITOPS_FIND_H_ */ > diff --git a/include/linux/bitops.h b/include/linux/bitops.h > index 602af23b98c7..f19a7bc8f559 100644 > --- a/include/linux/bitops.h > +++ b/include/linux/bitops.h > @@ -40,6 +40,11 @@ extern unsigned long __sw_hweight64(__u64 w); > (bit) < (size); \ > (bit) = find_next_zero_bit((addr), (size), (bit) + 1)) > > +#define for_each_set_clump8(start, clump, bits, size) \ > + for ((start) = find_first_clump8(&(clump), (bits), (size)); \ > + (start) < (size); \ > + (start) = find_next_clump8(&(clump), (bits), (start) + 8, (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..1b6f8a6f1957 100644 > --- a/lib/find_bit.c > +++ b/lib/find_bit.c > @@ -218,3 +218,84 @@ EXPORT_SYMBOL(find_next_bit_le); > #endif > > #endif /* __BIG_ENDIAN */ > + > +/** > + * bitmap_get_value8 - get an 8-bit value within a memory region > + * @bitmap: address to the bitmap memory region > + * @size: bitmap size in number of bits > + * @start: bit offset of the 8-bit value > + * > + * Returns the 8-bit value located at the @start bit offset within the > @bitmap > + * memory region. > + */ > +unsigned long bitmap_get_value8(const unsigned long *const bitmap, > + const unsigned int size, > + const unsigned int start) > +{ > + const size_t index = BIT_WORD(start); > + const unsigned int offset = start % BITS_PER_LONG; > + const unsigned int low_width = (offset + 8 > BITS_PER_LONG) ? > + BITS_PER_LONG - offset : 8; > + const unsigned long low = bitmap[index] >> offset; > + const unsigned long high = (low_width < 8 && start + 8 <= size) ? > + bitmap[index + 1] << low_width : 0; > + > + return (low | high) & 0xFF; > +} > +EXPORT_SYMBOL(bitmap_get_value8); > + > +/** > + * bitmap_set_value8 - set an 8-bit value within a memory region > + * @bitmap: address to the bitmap memory region > + * @size: bitmap size in number of bits > + * @value: the 8-bit value; values wider than 8 bits may clobber bitmap > + * @start: bit offset of the 8-bit value > + */ > +void bitmap_set_value8(unsigned long *const bitmap, const unsigned int size, > + const unsigned long value, const unsigned int start) > +{ > + const size_t index = BIT_WORD(start); > + const unsigned int offset = start % BITS_PER_LONG; > + const unsigned int low_width = (offset + 8 > BITS_PER_LONG) ? > + BITS_PER_LONG - offset : 8; > + const unsigned long low_mask = GENMASK(low_width - 1, 0) << offset; > + const unsigned int high_width = 8 - low_width; > + const unsigned long high_mask = GENMASK(high_width - 1, 0); > + > + /* set lower portion */ > + bitmap[index] &= ~low_mask; > + bitmap[index] |= value << offset; > + > + /* set higher portion if space available in bitmap */ > + if (high_width && start + 8 <= size) { > + bitmap[index + 1] &= ~high_mask; > + bitmap[index + 1] |= value >> low_width; > + } > +} > +EXPORT_SYMBOL(bitmap_set_value8); > + > +/** > + * find_next_clump8 - find next 8-bit clump with set bits in a memory region > + * @clump: location to store copy of found clump > + * @addr: address to base the search on > + * @offset: bit offset at which to start searching > + * @size: bitmap size in number of bits > + * > + * Returns the bit offset for the next set clump; the found clump value is > + * copied to the location pointed by @clump. If no bits are set, returns > @size. > + */ > +unsigned int find_next_clump8(unsigned long *const clump, > + const unsigned long *const addr, > + unsigned int offset, const unsigned int size) > +{ > + for (; offset < size; offset += 8) { > + *clump = bitmap_get_value8(addr, size, offset); > + if (!*clump) > + continue; > + > + return offset; > + } > + > + return size; > +} > +EXPORT_SYMBOL(find_next_clump8); > -- > 2.21.0 > -- With Best Regards, Andy Shevchenko
