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-rw-r--r--include/linux/bitfield.h38
1 files changed, 36 insertions, 2 deletions
diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h
index 4bbb5f1c8b5b..c9be1657f03d 100644
--- a/include/linux/bitfield.h
+++ b/include/linux/bitfield.h
@@ -19,6 +19,9 @@
*
* Example:
*
+ * #include <linux/bitfield.h>
+ * #include <linux/bits.h>
+ *
* #define REG_FIELD_A GENMASK(6, 0)
* #define REG_FIELD_B BIT(7)
* #define REG_FIELD_C GENMASK(15, 8)
@@ -41,6 +44,22 @@
#define __bf_shf(x) (__builtin_ffsll(x) - 1)
+#define __scalar_type_to_unsigned_cases(type) \
+ unsigned type: (unsigned type)0, \
+ signed type: (unsigned type)0
+
+#define __unsigned_scalar_typeof(x) typeof( \
+ _Generic((x), \
+ char: (unsigned char)0, \
+ __scalar_type_to_unsigned_cases(char), \
+ __scalar_type_to_unsigned_cases(short), \
+ __scalar_type_to_unsigned_cases(int), \
+ __scalar_type_to_unsigned_cases(long), \
+ __scalar_type_to_unsigned_cases(long long), \
+ default: (x)))
+
+#define __bf_cast_unsigned(type, x) ((__unsigned_scalar_typeof(type))(x))
+
#define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx) \
({ \
BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask), \
@@ -49,13 +68,27 @@
BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ? \
~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \
_pfx "value too large for the field"); \
- BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ull, \
+ BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) > \
+ __bf_cast_unsigned(_reg, ~0ull), \
_pfx "type of reg too small for mask"); \
__BUILD_BUG_ON_NOT_POWER_OF_2((_mask) + \
(1ULL << __bf_shf(_mask))); \
})
/**
+ * FIELD_MAX() - produce the maximum value representable by a field
+ * @_mask: shifted mask defining the field's length and position
+ *
+ * FIELD_MAX() returns the maximum value that can be held in the field
+ * specified by @_mask.
+ */
+#define FIELD_MAX(_mask) \
+ ({ \
+ __BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_MAX: "); \
+ (typeof(_mask))((_mask) >> __bf_shf(_mask)); \
+ })
+
+/**
* FIELD_FIT() - check if value fits in the field
* @_mask: shifted mask defining the field's length and position
* @_val: value to test against the field
@@ -64,7 +97,7 @@
*/
#define FIELD_FIT(_mask, _val) \
({ \
- __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_FIT: "); \
+ __BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_FIT: "); \
!((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \
})
@@ -110,6 +143,7 @@ static __always_inline u64 field_mask(u64 field)
{
return field / field_multiplier(field);
}
+#define field_max(field) ((typeof(field))field_mask(field))
#define ____MAKE_OP(type,base,to,from) \
static __always_inline __##type type##_encode_bits(base v, base field) \
{ \