@@ -77,6 +77,10 @@ struct device;
* bitmap_to_arr64(buf, src, nbits) Copy nbits from buf to u64[] 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
+ * bitmap_read(map, start, nbits) Read an nbits-sized value from
+ * map at start
+ * bitmap_write(map, value, start, nbits) Write an nbits-sized 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
@@ -599,6 +603,77 @@ static inline void bitmap_set_value8(unsigned long *map, unsigned long value,
map[index] |= value << offset;
}
+/**
+ * bitmap_read - read a value of n-bits from the memory region
+ * @map: address to the bitmap memory region
+ * @start: bit offset of the n-bit value
+ * @nbits: size of value in bits, nonzero, up to BITS_PER_LONG
+ *
+ * Returns: value of nbits located at the @start bit offset within the @map
+ * memory region.
+ */
+static inline unsigned long bitmap_read(const unsigned long *map,
+ unsigned long start,
+ unsigned long nbits)
+{
+ size_t index = BIT_WORD(start);
+ unsigned long offset = start % BITS_PER_LONG;
+ unsigned long space = BITS_PER_LONG - offset;
+ unsigned long value_low, value_high;
+
+ if (unlikely(!nbits))
+ return 0;
+
+ if (space >= nbits)
+ return (map[index] >> offset) & BITMAP_LAST_WORD_MASK(nbits);
+
+ value_low = map[index] & BITMAP_FIRST_WORD_MASK(start);
+ value_high = map[index + 1] & BITMAP_LAST_WORD_MASK(start + nbits);
+ return (value_low >> offset) | (value_high << space);
+}
+
+/**
+ * bitmap_write - write n-bit value within a memory region
+ * @map: address to the bitmap memory region
+ * @value: value to write, clamped to nbits
+ * @start: bit offset of the n-bit value
+ * @nbits: size of value in bits, nonzero, up to BITS_PER_LONG.
+ *
+ * bitmap_write() behaves as-if implemented as @nbits calls of __assign_bit(),
+ * i.e. bits beyond @nbits are ignored:
+ *
+ * for (bit = 0; bit < nbits; bit++)
+ * __assign_bit(start + bit, bitmap, val & BIT(bit));
+ */
+static inline void bitmap_write(unsigned long *map,
+ unsigned long value,
+ unsigned long start, unsigned long nbits)
+{
+ size_t index;
+ unsigned long offset;
+ unsigned long space;
+ unsigned long mask;
+ bool fit;
+
+ if (unlikely(!nbits))
+ return;
+
+ mask = BITMAP_LAST_WORD_MASK(nbits);
+ value &= mask;
+ offset = start % BITS_PER_LONG;
+ space = BITS_PER_LONG - offset;
+ fit = space >= nbits;
+ index = BIT_WORD(start);
+
+ map[index] &= (fit ? (~(mask << offset)) : ~BITMAP_FIRST_WORD_MASK(start));
+ map[index] |= value << offset;
+ if (fit)
+ return;
+
+ map[index + 1] &= BITMAP_FIRST_WORD_MASK(start + nbits);
+ map[index + 1] |= (value >> space);
+}
+
#endif /* __ASSEMBLY__ */
#endif /* __LINUX_BITMAP_H */