Provide an abstraction for leading and trailing zero bit counting
functions to hide compiler specific intrinsics and builtins.
Signed-off-by: Tyler Retzlaff <roret...@linux.microsoft.com>
---
lib/eal/include/meson.build | 1 +
lib/eal/include/rte_bitcount.h | 257 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 258 insertions(+)
create mode 100644 lib/eal/include/rte_bitcount.h
diff --git a/lib/eal/include/meson.build b/lib/eal/include/meson.build
index cfcd40a..8ff1d65 100644
--- a/lib/eal/include/meson.build
+++ b/lib/eal/include/meson.build
@@ -5,6 +5,7 @@ includes += include_directories('.')
headers += files(
'rte_alarm.h',
+ 'rte_bitcount.h',
'rte_bitmap.h',
'rte_bitops.h',
'rte_branch_prediction.h',
diff --git a/lib/eal/include/rte_bitcount.h b/lib/eal/include/rte_bitcount.h
new file mode 100644
index 0000000..2f4dd38
--- /dev/null
+++ b/lib/eal/include/rte_bitcount.h
@@ -0,0 +1,257 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright (C) 2022 Microsoft Corporation
+ */
+
+#ifndef EAL_BITCOUNT_H
+#define EAL_BITCOUNT_H
+
+#include <rte_compat.h>
+
+#ifdef RTE_TOOLCHAIN_MSVC
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change, or be removed, without prior notice
+ *
+ * Get the count of leading 0-bits in v.
+ *
+ * @param v
+ * The value.
+ * @return
+ * The count of leading zero bits.
+ */
+__rte_experimental
+static inline unsigned
+rte_clz(unsigned int v)
+{
+ unsigned long rv;
+
+ (void)_BitScanReverse(&rv, v);
+
+ return (unsigned)rv;
+}
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change, or be removed, without prior notice
+ *
+ * Get the count of leading 0-bits in v.
+ *
+ * @param v
+ * The value.
+ * @return
+ * The count of leading zero bits.
+ */
+__rte_experimental
+static inline unsigned
+rte_clzl(unsigned long v)
+{
+ unsigned long rv;
+
+ (void)_BitScanReverse(&rv, v);
+
+ return (unsigned)rv;
+}
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change, or be removed, without prior notice
+ *
+ * Get the count of leading 0-bits in v.
+ *
+ * @param v
+ * The value.
+ * @return
+ * The count of leading zero bits.
+ */
+__rte_experimental
+static inline unsigned
+rte_clzll(unsigned long long v)
+{
+ unsigned long rv;
+
+ (void)_BitScanReverse64(&rv, v);
+
+ return (unsigned)rv;
+}
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change, or be removed, without prior notice
+ *
+ * Get the count of trailing 0-bits in v.
+ *
+ * @param v
+ * The value.
+ * @return
+ * The count of trailing zero bits.
+ */
+__rte_experimental
+static inline unsigned
+rte_ctz(unsigned int v)
+{
+ unsigned long rv;
+
+ (void)_BitScanForward(&rv, v);
+
+ return (unsigned)rv;
+}
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change, or be removed, without prior notice
+ *
+ * Get the count of trailing 0-bits in v.
+ *
+ * @param v
+ * The value.
+ * @return
+ * The count of trailing zero bits.
+ */
+__rte_experimental
+static inline unsigned
+rte_ctzl(unsigned long v)
+{
+ unsigned long rv;
+
+ (void)_BitScanForward(&rv, v);
+
+ return (unsigned)rv;
+}
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change, or be removed, without prior notice
+ *
+ * Get the count of trailing 0-bits in v.
+ *
+ * @param v
+ * The value.
+ * @return
+ * The count of trailing zero bits.
+ */
+__rte_experimental
+static inline unsigned
+rte_ctzll(unsigned long long v)
+{
+ unsigned long rv;
+
+ (void)_BitScanForward64(&rv, v);
+
+ return (unsigned)rv;
+}
+
+#else
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change, or be removed, without prior notice
+ *
+ * Get the count of leading 0-bits in v.
+ *
+ * @param v
+ * The value.
+ * @return
+ * The count of leading zero bits.
+ */
+__rte_experimental
+static inline unsigned
+rte_clz(unsigned int v)
+{
+ return (unsigned)__builtin_clz(v);
+}
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change, or be removed, without prior notice
+ *
+ * Get the count of leading 0-bits in v.
+ *
+ * @param v
+ * The value.
+ * @return
+ * The count of leading zero bits.
+ */
+__rte_experimental
+static inline unsigned
+rte_clzl(unsigned long v)
+{
+ return (unsigned)__builtin_clzl(v);
+}
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change, or be removed, without prior notice
+ *
+ * Get the count of leading 0-bits in v.
+ *
+ * @param v
+ * The value.
+ * @return
+ * The count of leading zero bits.
+ */
+__rte_experimental
+static inline unsigned
+rte_clzll(unsigned long v)
+{
+ return (unsigned)__builtin_clzll(v);
+}
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change, or be removed, without prior notice
+ *
+ * Get the count of trailing 0-bits in v.
+ *
+ * @param v
+ * The value.
+ * @return
+ * The count of trailing zero bits.
+ */
+__rte_experimental
+static inline unsigned
+rte_ctz(unsigned int v)
+{
+ return (unsigned)__builtin_ctz(v);
+}
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change, or be removed, without prior notice
+ *
+ * Get the count of trailing 0-bits in v.
+ *
+ * @param v
+ * The value.
+ * @return
+ * The count of trailing zero bits.
+ */
+__rte_experimental
+static inline unsigned
+rte_ctzl(unsigned long v)
+{
+ return (unsigned)__builtin_ctzl(v);
+}
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change, or be removed, without prior notice
+ *
+ * Get the count of trailing 0-bits in v.
+ *
+ * @param v
+ * The value.
+ * @return
+ * The count of trailing zero bits.
+ */
+__rte_experimental
+static inline unsigned
+rte_ctzll(unsigned long v)
+{
+ return (unsigned)__builtin_ctzll(v);
+}
+
+#endif
+
+#endif /* EAL_BITCOUNT_H */
+
--
1.8.3.1
