[PATCH v2 1/5] eal: extend bit manipulation functionality

["Mattias Rönnblom" <mattias.ronnblom@ericsson.com>]

Add functionality to test and modify the value of individual bits in
32-bit or 64-bit words.

These functions have no implications on memory ordering, atomicity and
does not use volatile and thus does not prevent any compiler
optimizations.

Signed-off-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com>
Acked-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>

--

RFC v6:
 * Have rte_bit_test() accept const-marked bitsets.

RFC v4:
 * Add rte_bit_flip() which, believe it or not, flips the value of a bit.
 * Mark macro-generated private functions as experimental.
 * Use macros to generate *assign*() functions.

RFC v3:
 * Work around lack of C++ support for _Generic (Tyler Retzlaff).
 * Fix ','-related checkpatch warnings.
---
 lib/eal/include/rte_bitops.h | 259 ++++++++++++++++++++++++++++++++++-
 1 file changed, 257 insertions(+), 2 deletions(-)

diff --git a/lib/eal/include/rte_bitops.h b/lib/eal/include/rte_bitops.h
index 449565eeae..3297133e22 100644
--- a/lib/eal/include/rte_bitops.h
+++ b/lib/eal/include/rte_bitops.h
@@ -2,6 +2,7 @@
  * Copyright(c) 2020 Arm Limited
  * Copyright(c) 2010-2019 Intel Corporation
  * Copyright(c) 2023 Microsoft Corporation
+ * Copyright(c) 2024 Ericsson AB
  */
 
 #ifndef _RTE_BITOPS_H_
@@ -11,12 +12,14 @@
  * @file
  * Bit Operations
  *
- * This file defines a family of APIs for bit operations
- * without enforcing memory ordering.
+ * This file provides functionality for low-level, single-word
+ * arithmetic and bit-level operations, such as counting or
+ * setting individual bits.
  */
 
 #include <stdint.h>
 
+#include <rte_compat.h>
 #include <rte_debug.h>
 
 #ifdef __cplusplus
@@ -105,6 +108,196 @@ extern "C" {
 #define RTE_FIELD_GET64(mask, reg) \
 		((typeof(mask))(((reg) & (mask)) >> rte_ctz64(mask)))
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Test bit in word.
+ *
+ * Generic selection macro to test the value of a bit in a 32-bit or
+ * 64-bit word. The type of operation depends on the type of the @c
+ * addr parameter.
+ *
+ * This macro does not give any guarantees in regards to memory
+ * ordering or atomicity.
+ *
+ * @param addr
+ *   A pointer to the word to modify.
+ * @param nr
+ *   The index of the bit.
+ */
+#define rte_bit_test(addr, nr)					\
+	_Generic((addr),					\
+		uint32_t *: __rte_bit_test32,			\
+		const uint32_t *: __rte_bit_test32,		\
+		uint64_t *: __rte_bit_test64,			\
+		const uint64_t *: __rte_bit_test64)(addr, nr)
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Set bit in word.
+ *
+ * Generic selection macro to set a bit in a 32-bit or 64-bit
+ * word. The type of operation depends on the type of the @c addr
+ * parameter.
+ *
+ * This macro does not give any guarantees in regards to memory
+ * ordering or atomicity.
+ *
+ * @param addr
+ *   A pointer to the word to modify.
+ * @param nr
+ *   The index of the bit.
+ */
+#define rte_bit_set(addr, nr)				\
+	_Generic((addr),				\
+		 uint32_t *: __rte_bit_set32,		\
+		 uint64_t *: __rte_bit_set64)(addr, nr)
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Clear bit in word.
+ *
+ * Generic selection macro to clear a bit in a 32-bit or 64-bit
+ * word. The type of operation depends on the type of the @c addr
+ * parameter.
+ *
+ * This macro does not give any guarantees in regards to memory
+ * ordering or atomicity.
+ *
+ * @param addr
+ *   A pointer to the word to modify.
+ * @param nr
+ *   The index of the bit.
+ */
+#define rte_bit_clear(addr, nr)					\
+	_Generic((addr),					\
+		 uint32_t *: __rte_bit_clear32,			\
+		 uint64_t *: __rte_bit_clear64)(addr, nr)
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Assign a value to a bit in word.
+ *
+ * Generic selection macro to assign a value to a bit in a 32-bit or 64-bit
+ * word. The type of operation depends on the type of the @c addr parameter.
+ *
+ * This macro does not give any guarantees in regards to memory
+ * ordering or atomicity.
+ *
+ * @param addr
+ *   A pointer to the word to modify.
+ * @param nr
+ *   The index of the bit.
+ * @param value
+ *   The new value of the bit - true for '1', or false for '0'.
+ */
+#define rte_bit_assign(addr, nr, value)					\
+	_Generic((addr),						\
+		 uint32_t *: __rte_bit_assign32,			\
+		 uint64_t *: __rte_bit_assign64)(addr, nr, value)
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Flip a bit in word.
+ *
+ * Generic selection macro to change the value of a bit to '0' if '1'
+ * or '1' if '0' in a 32-bit or 64-bit word. The type of operation
+ * depends on the type of the @c addr parameter.
+ *
+ * This macro does not give any guarantees in regards to memory
+ * ordering or atomicity.
+ *
+ * @param addr
+ *   A pointer to the word to modify.
+ * @param nr
+ *   The index of the bit.
+ */
+#define rte_bit_flip(addr, nr)						\
+	_Generic((addr),						\
+		 uint32_t *: __rte_bit_flip32,				\
+		 uint64_t *: __rte_bit_flip64)(addr, nr)
+
+#define __RTE_GEN_BIT_TEST(family, fun, qualifier, size)		\
+	__rte_experimental						\
+	static inline bool						\
+	__rte_bit_ ## family ## fun ## size(const qualifier uint ## size ## _t *addr, \
+					    unsigned int nr)		\
+	{								\
+		RTE_ASSERT(nr < size);					\
+									\
+		uint ## size ## _t mask = (uint ## size ## _t)1 << nr;	\
+		return *addr & mask;					\
+	}
+
+#define __RTE_GEN_BIT_SET(family, fun, qualifier, size)			\
+	__rte_experimental						\
+	static inline void						\
+	__rte_bit_ ## family ## fun ## size(qualifier uint ## size ## _t *addr, \
+					    unsigned int nr)		\
+	{								\
+		RTE_ASSERT(nr < size);					\
+									\
+		uint ## size ## _t mask = (uint ## size ## _t)1 << nr;	\
+		*addr |= mask;						\
+	}								\
+
+#define __RTE_GEN_BIT_CLEAR(family, fun, qualifier, size)		\
+	__rte_experimental						\
+	static inline void						\
+	__rte_bit_ ## family ## fun ## size(qualifier uint ## size ## _t *addr, \
+					    unsigned int nr)		\
+	{								\
+		RTE_ASSERT(nr < size);					\
+									\
+		uint ## size ## _t mask = ~((uint ## size ## _t)1 << nr); \
+		(*addr) &= mask;					\
+	}								\
+
+#define __RTE_GEN_BIT_ASSIGN(family, fun, qualifier, size)		\
+	__rte_experimental						\
+	static inline void						\
+	__rte_bit_ ## family ## fun ## size(qualifier uint ## size ## _t *addr, \
+					    unsigned int nr, bool value) \
+	{								\
+		if (value)						\
+			__rte_bit_ ## family ## set ## size(addr, nr);	\
+		else							\
+			__rte_bit_ ## family ## clear ## size(addr, nr); \
+	}
+
+#define __RTE_GEN_BIT_FLIP(family, fun, qualifier, size)		\
+	__rte_experimental						\
+	static inline void						\
+	__rte_bit_ ## family ## fun ## size(qualifier uint ## size ## _t *addr, \
+					    unsigned int nr)		\
+	{								\
+		bool value;						\
+									\
+		value = __rte_bit_ ## family ## test ## size(addr, nr);	\
+		__rte_bit_ ## family ## assign ## size(addr, nr, !value); \
+	}
+
+__RTE_GEN_BIT_TEST(, test,, 32)
+__RTE_GEN_BIT_SET(, set,, 32)
+__RTE_GEN_BIT_CLEAR(, clear,, 32)
+__RTE_GEN_BIT_ASSIGN(, assign,, 32)
+__RTE_GEN_BIT_FLIP(, flip,, 32)
+
+__RTE_GEN_BIT_TEST(, test,, 64)
+__RTE_GEN_BIT_SET(, set,, 64)
+__RTE_GEN_BIT_CLEAR(, clear,, 64)
+__RTE_GEN_BIT_ASSIGN(, assign,, 64)
+__RTE_GEN_BIT_FLIP(, flip,, 64)
+
 /*------------------------ 32-bit relaxed operations ------------------------*/
 
 /**
@@ -787,6 +980,68 @@ rte_log2_u64(uint64_t v)
 
 #ifdef __cplusplus
 }
+
+/*
+ * Since C++ doesn't support generic selection (i.e., _Generic),
+ * function overloading is used instead. Such functions must be
+ * defined outside 'extern "C"' to be accepted by the compiler.
+ */
+
+#undef rte_bit_test
+#undef rte_bit_set
+#undef rte_bit_clear
+#undef rte_bit_assign
+#undef rte_bit_flip
+
+#define __RTE_BIT_OVERLOAD_SZ_2(fun, qualifier, size, arg1_type, arg1_name) \
+	static inline void						\
+	rte_bit_ ## fun(qualifier uint ## size ## _t *addr,		\
+			arg1_type arg1_name)				\
+	{								\
+		__rte_bit_ ## fun ## size(addr, arg1_name);		\
+	}
+
+#define __RTE_BIT_OVERLOAD_2(fun, qualifier, arg1_type, arg1_name)	\
+	__RTE_BIT_OVERLOAD_SZ_2(fun, qualifier, 32, arg1_type, arg1_name) \
+	__RTE_BIT_OVERLOAD_SZ_2(fun, qualifier, 64, arg1_type, arg1_name)
+
+#define __RTE_BIT_OVERLOAD_SZ_2R(fun, qualifier, size, ret_type, arg1_type, \
+				 arg1_name)				\
+	static inline ret_type						\
+	rte_bit_ ## fun(qualifier uint ## size ## _t *addr,		\
+			arg1_type arg1_name)				\
+	{								\
+		return __rte_bit_ ## fun ## size(addr, arg1_name);	\
+	}
+
+#define __RTE_BIT_OVERLOAD_2R(fun, qualifier, ret_type, arg1_type, arg1_name) \
+	__RTE_BIT_OVERLOAD_SZ_2R(fun, qualifier, 32, ret_type, arg1_type, \
+				 arg1_name)				\
+	__RTE_BIT_OVERLOAD_SZ_2R(fun, qualifier, 64, ret_type, arg1_type, \
+				 arg1_name)
+
+#define __RTE_BIT_OVERLOAD_SZ_3(fun, qualifier, size, arg1_type, arg1_name, \
+				arg2_type, arg2_name)			\
+	static inline void						\
+	rte_bit_ ## fun(uint ## size ## _t *addr, arg1_type arg1_name,	\
+			arg2_type arg2_name)				\
+	{								\
+		__rte_bit_ ## fun ## size(addr, arg1_name, arg2_name);	\
+	}
+
+#define __RTE_BIT_OVERLOAD_3(fun, qualifier, arg1_type, arg1_name, arg2_type, \
+			     arg2_name)					\
+	__RTE_BIT_OVERLOAD_SZ_3(fun, qualifier, 32, arg1_type, arg1_name, \
+				arg2_type, arg2_name)			\
+	__RTE_BIT_OVERLOAD_SZ_3(fun, qualifier, 64, arg1_type, arg1_name, \
+				arg2_type, arg2_name)
+
+__RTE_BIT_OVERLOAD_2R(test, const, bool, unsigned int, nr)
+__RTE_BIT_OVERLOAD_2(set,, unsigned int, nr)
+__RTE_BIT_OVERLOAD_2(clear,, unsigned int, nr)
+__RTE_BIT_OVERLOAD_3(assign,, unsigned int, nr, bool, value)
+__RTE_BIT_OVERLOAD_2(flip,, unsigned int, nr)
+
 #endif
 
 #endif /* _RTE_BITOPS_H_ */
-- 
2.34.1