bitmaps: import for_each_set_bit() macro

Import for_each_set_bit() and associated macros and functions from
Linux. This is useful in parsing interrupt registers and take action on
each bit that is set.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 4a54ae0..fbbb67c 100644 (file)
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -20,4 +20,65 @@ static inline void bitmap_zero(unsigned long *dst, int nbits)
        }
 }
 
+static inline unsigned long
+find_next_bit(const unsigned long *addr, unsigned long size,
+             unsigned long offset)
+{
+       const unsigned long *p = addr + BIT_WORD(offset);
+       unsigned long result = offset & ~(BITS_PER_LONG - 1);
+       unsigned long tmp;
+
+       if (offset >= size)
+               return size;
+       size -= result;
+       offset %= BITS_PER_LONG;
+       if (offset) {
+               tmp = *(p++);
+               tmp &= (~0UL << offset);
+               if (size < BITS_PER_LONG)
+                       goto found_first;
+               if (tmp)
+                       goto found_middle;
+               size -= BITS_PER_LONG;
+               result += BITS_PER_LONG;
+       }
+       while (size & ~(BITS_PER_LONG - 1)) {
+               tmp = *(p++);
+               if ((tmp))
+                       goto found_middle;
+               result += BITS_PER_LONG;
+               size -= BITS_PER_LONG;
+       }
+       if (!size)
+               return result;
+       tmp = *p;
+
+found_first:
+       tmp &= (~0UL >> (BITS_PER_LONG - size));
+       if (tmp == 0UL)         /* Are any bits set? */
+               return result + size;   /* Nope. */
+found_middle:
+       return result + __ffs(tmp);
+}
+
+/*
+ * Find the first set bit in a memory region.
+ */
+static inline unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
+{
+       unsigned long idx;
+
+       for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
+               if (addr[idx])
+                       return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);
+       }
+
+       return size;
+}
+
+#define for_each_set_bit(bit, addr, size) \
+       for ((bit) = find_first_bit((addr), (size));            \
+            (bit) < (size);                                    \
+            (bit) = find_next_bit((addr), (size), (bit) + 1))
+
 #endif /* __LINUX_BITMAP_H */