[PATCH v6] hash: add XOR32 hash function

[Bili Dong <qobilidop@gmail.com>]

An XOR32 hash is needed in the Software Switch (SWX) Pipeline for its
use case in P4. We implement it in this patch so it could be easily
registered in the pipeline later.

Signed-off-by: Bili Dong <qobilidop@gmail.com>
---
 .mailmap                       |  1 +
 app/test/test_hash_functions.c | 33 +++++++++++--
 lib/hash/rte_hash_xor.h        | 87 ++++++++++++++++++++++++++++++++++
 3 files changed, 118 insertions(+), 3 deletions(-)
 create mode 100644 lib/hash/rte_hash_xor.h

diff --git a/.mailmap b/.mailmap
index a9f4f28fba..3e9bec29d5 100644
--- a/.mailmap
+++ b/.mailmap
@@ -159,6 +159,7 @@ Bernard Iremonger <bernard.iremonger@intel.com>
 Bert van Leeuwen <bert.vanleeuwen@netronome.com>
 Bhagyada Modali <bhagyada.modali@amd.com>
 Bharat Mota <bmota@vmware.com>
+Bili Dong <qobilidop@gmail.com>
 Bill Hong <bhong@brocade.com>
 Billy McFall <bmcfall@redhat.com>
 Billy O'Mahony <billy.o.mahony@intel.com>
diff --git a/app/test/test_hash_functions.c b/app/test/test_hash_functions.c
index 76d51b6e71..53e296fec4 100644
--- a/app/test/test_hash_functions.c
+++ b/app/test/test_hash_functions.c
@@ -15,6 +15,7 @@
 #include <rte_hash.h>
 #include <rte_jhash.h>
 #include <rte_hash_crc.h>
+#include <rte_hash_xor.h>
 
 #include "test.h"
 
@@ -22,8 +23,8 @@
  * Hash values calculated for key sizes from array "hashtest_key_lens"
  * and for initial values from array "hashtest_initvals.
  * Each key will be formed by increasing each byte by 1:
- * e.g.: key size = 4, key = 0x03020100
- *       key size = 8, key = 0x0706050403020100
+ * e.g.: key size = 4, key = 0x00010203
+ *       key size = 8, key = 0x0001020304050607
  */
 static uint32_t hash_values_jhash[2][12] = {{
 	0x8ba9414b, 0xdf0d39c9,
@@ -51,6 +52,19 @@ static uint32_t hash_values_crc[2][12] = {{
 	0x789c104f, 0x53028d3e
 }
 };
+static uint32_t hash_values_xor32[2][12] = {{
+	0x00000000, 0x00010000,
+	0x00010203, 0x04040404, 0x00000000, 0x00000000,
+	0x00000000, 0x00000000, 0x0c040404, 0x000d0e0f,
+	0x04212223, 0x04040404
+},
+{
+	0xdeadbeef, 0xdeacbeef,
+	0xdeacbcec, 0xdaa9baeb, 0xdeadbeef, 0xdeadbeef,
+	0xdeadbeef, 0xdeadbeef, 0xd2a9baeb, 0xdea0b0e0,
+	0xda8c9ccc, 0xdaa9baeb
+}
+};
 
 /*******************************************************************************
  * Hash function performance test configuration section. Each performance test
@@ -61,7 +75,7 @@ static uint32_t hash_values_crc[2][12] = {{
  */
 #define HASHTEST_ITERATIONS 1000000
 #define MAX_KEYSIZE 64
-static rte_hash_function hashtest_funcs[] = {rte_jhash, rte_hash_crc};
+static rte_hash_function hashtest_funcs[] = {rte_jhash, rte_hash_crc, rte_hash_xor32};
 static uint32_t hashtest_initvals[] = {0, 0xdeadbeef};
 static uint32_t hashtest_key_lens[] = {
 	1, 2,                 /* Unusual key sizes */
@@ -85,6 +99,9 @@ get_hash_name(rte_hash_function f)
 	if (f == rte_hash_crc)
 		return "rte_hash_crc";
 
+	if (f == rte_hash_xor32)
+		return "rte_hash_xor32";
+
 	return "UnknownHash";
 }
 
@@ -173,6 +190,16 @@ verify_precalculated_hash_func_tests(void)
 				       hash_values_crc[j][i], hash);
 				return -1;
 			}
+
+			hash = rte_hash_xor32(key, hashtest_key_lens[i],
+					hashtest_initvals[j]);
+			if (hash != hash_values_xor32[j][i]) {
+				printf("XOR32 for %u bytes with initial value 0x%x."
+				       " Expected 0x%x, but got 0x%x\n",
+				       hashtest_key_lens[i], hashtest_initvals[j],
+				       hash_values_xor32[j][i], hash);
+				return -1;
+			}
 		}
 	}
 
diff --git a/lib/hash/rte_hash_xor.h b/lib/hash/rte_hash_xor.h
new file mode 100644
index 0000000000..366adbe64c
--- /dev/null
+++ b/lib/hash/rte_hash_xor.h
@@ -0,0 +1,87 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2023 Intel Corporation
+ */
+
+#ifndef _RTE_HASH_XOR_H_
+#define _RTE_HASH_XOR_H_
+
+/**
+ * @file
+ *
+ * RTE XOR Hash
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdint.h>
+
+#include <rte_byteorder.h>
+
+/**
+ * Calculate XOR32 hash on user-supplied byte array.
+ *
+ * @param data
+ *   Data to perform hash on.
+ * @param data_len
+ *   How many bytes to use to calculate hash value.
+ * @param init_val
+ *   Value to initialise hash generator.
+ * @return
+ *   32bit calculated hash value.
+ */
+static inline uint32_t
+rte_hash_xor32(const void *data, uint32_t data_len, uint32_t init_val)
+{
+	uint32_t hash32;
+	const uint8_t *data8 = data;
+
+	/* Minimize byte order conversions depending on data length. */
+	if (data_len >= 8) {
+		/* For longer arrays, operate in big endian. */
+		uint64_t hash64 = rte_cpu_to_be_32(init_val);
+
+		uint32_t i;
+		for (i = 0; i < data_len / 8; i++) {
+			hash64 ^= *(const uint64_t *)data8;
+			data8 += 8;
+		}
+
+		if (data_len & 0x4) {
+			hash64 ^= *(const uint32_t *)data8;
+			data8 += 4;
+		}
+
+		hash32 = rte_be_to_cpu_32(hash64 ^ (hash64 >> 32));
+	} else {
+		/* For shorter arrays, operate in host endian. */
+		hash32 = init_val;
+
+		if (data_len & 0x4) {
+			hash32 ^= rte_be_to_cpu_32(*(const uint32_t *)data8);
+			data8 += 4;
+		}
+	}
+
+	/* Deal with remaining (< 4) bytes. */
+
+	uint8_t bit_offset = 0;
+
+	if (data_len & 0x2) {
+		hash32 ^= (uint32_t)rte_be_to_cpu_16(*(const uint16_t *)data8) << 16;
+		data8 += 2;
+		bit_offset += 16;
+	}
+
+	if (data_len & 0x1)
+		hash32 ^= (uint32_t)(*(const uint8_t *)data8) << (24 - bit_offset);
+
+	return hash32;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _RTE_HASH_XOR_H_ */
-- 
2.34.1