[PATCH v10 2/5] include/linux_scaffold: add FIELD_GET() bitfield helper

[Xin Wang <x.wang@intel.com>]

Add __bf_shf() and FIELD_GET() so code can extract bitfields from
registers using a mask, matching the common Linux FIELD_GET()
semantics without pulling in kernel headers.

V2: (Matt Roper)
 - use the libc ffsll() helper instead of __builtin_ffsll()

CC: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Xin Wang <x.wang@intel.com>
---
 include/linux_scaffold.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux_scaffold.h b/include/linux_scaffold.h
index f6620ad0a..281aa5e73 100644
--- a/include/linux_scaffold.h
+++ b/include/linux_scaffold.h
@@ -4,6 +4,7 @@
 #define _INTEL_GPU_COMMANDS_SCAFFOLD_H_
 
 #include <stdint.h>
+#include <strings.h>
 
 typedef uint8_t  u8;
 typedef uint16_t u16;
@@ -51,4 +52,9 @@ static inline s64 sign_extend64(u64 value, int index)
 #define BITS_PER_LONG BITS_PER_TYPE(long)
 #define BITS_PER_LONG_LONG BITS_PER_TYPE(long long)
 
+#define __bf_shf(x) (ffsll(x) - 1)
+
+#define FIELD_GET(mask, reg) \
+	(typeof(mask))(((reg) & (mask)) >> __bf_shf(mask))
+
 #endif /* _INTEL_GPU_COMMANDS_SCAFFOLD_H_ */
-- 
2.43.0