vppinfra: add clear_lowest_set_bit() function, use BMI2 if available

[vpp.git] / src / vppinfra / clib.h

diff --git a/src/vppinfra/clib.h b/src/vppinfra/clib.h
index be21cad..05af8fe 100644 (file)
--- a/src/vppinfra/clib.h
+++ b/src/vppinfra/clib.h
@@ -38,6 +38,7 @@
 #ifndef included_clib_h
 #define included_clib_h
 
+#include <stddef.h>
 #include <vppinfra/config.h>
 
 #ifdef  __x86_64__
@@ -66,8 +67,8 @@
 #define ARRAY_LEN(x)   (sizeof (x)/sizeof (x[0]))
 
 #define _STRUCT_FIELD(t,f) (((t *) 0)->f)
-#define STRUCT_OFFSET_OF(t,f) ((uword) & _STRUCT_FIELD (t, f))
-#define STRUCT_BIT_OFFSET_OF(t,f) (BITS(u8) * (uword) & _STRUCT_FIELD (t, f))
+#define STRUCT_OFFSET_OF(t,f) offsetof(t, f)
+#define STRUCT_BIT_OFFSET_OF(t,f) (BITS(u8) * STRUCT_OFFSET_OF (t, f))
 #define STRUCT_SIZE_OF(t,f)   (sizeof (_STRUCT_FIELD (t, f)))
 #define STRUCT_BITS_OF(t,f)   (BITS (_STRUCT_FIELD (t, f)))
 #define STRUCT_ARRAY_LEN(t,f) ARRAY_LEN (_STRUCT_FIELD (t, f))
@@ -99,6 +100,7 @@
 #define __clib_aligned(x) __attribute__ ((aligned(x)))
 #define __clib_section(s) __attribute__ ((section(s)))
 #define __clib_warn_unused_result __attribute__ ((warn_unused_result))
+#define __clib_export __attribute__ ((visibility("default")))
 
 #define never_inline __attribute__ ((__noinline__))
 
@@ -156,6 +158,16 @@
 #endif
 
 #if defined (count_leading_zeros)
+always_inline uword
+clear_lowest_set_bit (uword x)
+{
+#ifdef __BMI2__
+  return _blsr_u64 (x);
+#else
+  return x ^ (1ULL << count_trailing_zeros (x));
+#endif
+}
+
 always_inline uword
 min_log2 (uword x)
 {
@@ -330,6 +342,14 @@ extract_bits (uword x, int start, int count)
   _x < _y ? _x : _y;                           \
 })
 
+#define clib_clamp(x,lo,hi)                    \
+({                                             \
+  __typeof__ (x) _x = (x);                     \
+  __typeof__ (lo) _lo = (lo);                  \
+  __typeof__ (hi) _hi = (hi);                  \
+  _x < _lo ? _lo : (_x > _hi ? _hi : _x);      \
+})
+
 #define clib_abs(x)                            \
 ({                                             \
   __typeof__ (x) _x = (x);                     \