[v18,01/14] bitops: Introduce the for_each_set_clump8 macro
diff mbox series

Message ID 893c3b4f03266c9496137cc98ac2b1bd27f92c73.1570641097.git.vilhelm.gray@gmail.com
State New
Headers show
Series
  • Introduce the for_each_set_clump8 macro
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Commit Message

William Breathitt Gray Oct. 9, 2019, 5:14 p.m. UTC
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.

Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Suggested-by: Lukas Wunner <lukas@wunner.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
 include/asm-generic/bitops/find.h | 17 +++++++++++++++
 include/linux/bitmap.h            | 35 +++++++++++++++++++++++++++++++
 include/linux/bitops.h            |  5 +++++
 lib/find_bit.c                    | 14 +++++++++++++
 4 files changed, 71 insertions(+)

Comments

Andrew Morton Oct. 9, 2019, 9:18 p.m. UTC | #1
On Wed,  9 Oct 2019 13:14:37 -0400 William Breathitt Gray <vilhelm.gray@gmail.com> 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.
> 
> ...
>  
> +#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), (size), (start) + 8))
> +

It wouldn't hurt to give this some documentation.  In kerneldoc form, I
guess.
Andy Shevchenko Oct. 10, 2019, 1:18 p.m. UTC | #2
On Wed, Oct 09, 2019 at 02:18:55PM -0700, Andrew Morton wrote:
> On Wed,  9 Oct 2019 13:14:37 -0400 William Breathitt Gray <vilhelm.gray@gmail.com> 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.
> > 
> > ...
> >  
> > +#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), (size), (start) + 8))
> > +
> 
> It wouldn't hurt to give this some documentation.  In kerneldoc form, I
> guess.

Good idea!

William, I have just tested your series with a complex hardware setup,
everything works to me.

I think I may give

Tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

for this patch as well.

Patch
diff mbox series

diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h
index 8a1ee10014de..9fdf21302fdf 100644
--- a/include/asm-generic/bitops/find.h
+++ b/include/asm-generic/bitops/find.h
@@ -80,4 +80,21 @@  extern unsigned long find_first_zero_bit(const unsigned long *addr,
 
 #endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
 
+/**
+ * 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
+ * @size: bitmap size in number of bits
+ * @offset: bit offset at which to start searching
+ *
+ * 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.
+ */
+extern unsigned long find_next_clump8(unsigned long *clump,
+				      const unsigned long *addr,
+				      unsigned long size, unsigned long offset);
+
+#define find_first_clump8(clump, bits, size) \
+	find_next_clump8((clump), (bits), (size), 0)
+
 #endif /*_ASM_GENERIC_BITOPS_FIND_H_ */
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 90528f12bdfa..761fab5b60a7 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -66,6 +66,8 @@ 
  *  bitmap_allocate_region(bitmap, pos, order)  Allocate specified bit region
  *  bitmap_from_arr32(dst, buf, nbits)          Copy nbits from u32[] buf to dst
  *  bitmap_to_arr32(buf, src, nbits)            Copy nbits from buf to u32[] dst
+ *  bitmap_get_value8(map, start)               Get 8bit value from map at start
+ *  bitmap_set_value8(map, value, start)        Set 8bit value to map at start
  *
  * Note, bitmap_zero() and bitmap_fill() operate over the region of
  * unsigned longs, that is, bits behind bitmap till the unsigned long
@@ -488,6 +490,39 @@  static inline void bitmap_from_u64(unsigned long *dst, u64 mask)
 		dst[1] = mask >> 32;
 }
 
+/**
+ * bitmap_get_value8 - get an 8-bit value within a memory region
+ * @map: address to the bitmap memory region
+ * @start: bit offset of the 8-bit value; must be a multiple of 8
+ *
+ * Returns the 8-bit value located at the @start bit offset within the @src
+ * memory region.
+ */
+static inline unsigned long bitmap_get_value8(const unsigned long *map,
+					      unsigned long start)
+{
+	const size_t index = BIT_WORD(start);
+	const unsigned long offset = start % BITS_PER_LONG;
+
+	return (map[index] >> offset) & 0xFF;
+}
+
+/**
+ * bitmap_set_value8 - set an 8-bit value within a memory region
+ * @map: address to the bitmap memory region
+ * @value: the 8-bit value; values wider than 8 bits may clobber bitmap
+ * @start: bit offset of the 8-bit value; must be a multiple of 8
+ */
+static inline void bitmap_set_value8(unsigned long *map, unsigned long value,
+				     unsigned long start)
+{
+	const size_t index = BIT_WORD(start);
+	const unsigned long offset = start % BITS_PER_LONG;
+
+	map[index] &= ~(0xFF << offset);
+	map[index] |= value << offset;
+}
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* __LINUX_BITMAP_H */
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index cf074bce3eb3..fb94a10f7853 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), (size), (start) + 8))
+
 static inline int get_bitmask_order(unsigned int count)
 {
 	int order;
diff --git a/lib/find_bit.c b/lib/find_bit.c
index 5c51eb45178a..e35a76b291e6 100644
--- a/lib/find_bit.c
+++ b/lib/find_bit.c
@@ -214,3 +214,17 @@  EXPORT_SYMBOL(find_next_bit_le);
 #endif
 
 #endif /* __BIG_ENDIAN */
+
+unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
+			       unsigned long size, unsigned long offset)
+{
+	offset = find_next_bit(addr, size, offset);
+	if (offset == size)
+		return size;
+
+	offset = round_down(offset, 8);
+	*clump = bitmap_get_value8(addr, offset);
+
+	return offset;
+}
+EXPORT_SYMBOL(find_next_clump8);