[dpdk-dev] [PATCH v3 2/2] hash: fix CRC32c computation
Didier Pallard
didier.pallard at 6wind.com
Fri Feb 19 12:00:31 CET 2016
Fix crc32c hash functions to return a valid crc32c value for
data lengthes not multiple of 4 bytes.
ARM code is not tested.
Signed-off-by: Didier Pallard <didier.pallard at 6wind.com>
Acked-by: David Marchand <david.marchand at 6wind.com>
---
doc/guides/rel_notes/release_16_04.rst | 5 ++
lib/librte_hash/rte_crc_arm64.h | 64 +++++++++++++++++
lib/librte_hash/rte_hash_crc.h | 125 ++++++++++++++++++++++++++-------
3 files changed, 167 insertions(+), 27 deletions(-)
diff --git a/doc/guides/rel_notes/release_16_04.rst b/doc/guides/rel_notes/release_16_04.rst
index eb1b3b2..45b35dd 100644
--- a/doc/guides/rel_notes/release_16_04.rst
+++ b/doc/guides/rel_notes/release_16_04.rst
@@ -68,6 +68,11 @@ Drivers
Libraries
~~~~~~~~~
+* **hash: Fixed CRC32c hash computation for non multiple of 4 bytes sizes.**
+
+ Fix crc32c hash functions to return a valid crc32c value for data lengthes
+ not multiple of 4 bytes.
+
Examples
~~~~~~~~
diff --git a/lib/librte_hash/rte_crc_arm64.h b/lib/librte_hash/rte_crc_arm64.h
index 02e26bc..7dd6334 100644
--- a/lib/librte_hash/rte_crc_arm64.h
+++ b/lib/librte_hash/rte_crc_arm64.h
@@ -50,6 +50,28 @@ extern "C" {
#include <rte_common.h>
static inline uint32_t
+crc32c_arm64_u8(uint8_t data, uint32_t init_val)
+{
+ asm(".arch armv8-a+crc");
+ __asm__ volatile(
+ "crc32cb %w[crc], %w[crc], %w[value]"
+ : [crc] "+r" (init_val)
+ : [value] "r" (data));
+ return init_val;
+}
+
+static inline uint32_t
+crc32c_arm64_u16(uint16_t data, uint32_t init_val)
+{
+ asm(".arch armv8-a+crc");
+ __asm__ volatile(
+ "crc32ch %w[crc], %w[crc], %w[value]"
+ : [crc] "+r" (init_val)
+ : [value] "r" (data));
+ return init_val;
+}
+
+static inline uint32_t
crc32c_arm64_u32(uint32_t data, uint32_t init_val)
{
asm(".arch armv8-a+crc");
@@ -103,6 +125,48 @@ rte_hash_crc_init_alg(void)
}
/**
+ * Use single crc32 instruction to perform a hash on a 1 byte value.
+ * Fall back to software crc32 implementation in case arm64 crc intrinsics is
+ * not supported
+ *
+ * @param data
+ * Data to perform hash on.
+ * @param init_val
+ * Value to initialise hash generator.
+ * @return
+ * 32bit calculated hash value.
+ */
+static inline uint32_t
+rte_hash_crc_1byte(uint8_t data, uint32_t init_val)
+{
+ if (likely(crc32_alg & CRC32_ARM64))
+ return crc32c_arm64_u8(data, init_val);
+
+ return crc32c_1byte(data, init_val);
+}
+
+/**
+ * Use single crc32 instruction to perform a hash on a 2 bytes value.
+ * Fall back to software crc32 implementation in case arm64 crc intrinsics is
+ * not supported
+ *
+ * @param data
+ * Data to perform hash on.
+ * @param init_val
+ * Value to initialise hash generator.
+ * @return
+ * 32bit calculated hash value.
+ */
+static inline uint32_t
+rte_hash_crc_2byte(uint16_t data, uint32_t init_val)
+{
+ if (likely(crc32_alg & CRC32_ARM64))
+ return crc32c_arm64_u16(data, init_val);
+
+ return crc32c_2bytes(data, init_val);
+}
+
+/**
* Use single crc32 instruction to perform a hash on a 4 byte value.
* Fall back to software crc32 implementation in case arm64 crc intrinsics is
* not supported
diff --git a/lib/librte_hash/rte_hash_crc.h b/lib/librte_hash/rte_hash_crc.h
index 78a34b7..63e74aa 100644
--- a/lib/librte_hash/rte_hash_crc.h
+++ b/lib/librte_hash/rte_hash_crc.h
@@ -328,6 +328,28 @@ static const uint32_t crc32c_tables[8][256] = {{
crc32c_tables[(n)-1][((crc) >> 8) & 0xFF])
static inline uint32_t
+crc32c_1byte(uint8_t data, uint32_t init_val)
+{
+ uint32_t crc;
+ crc = init_val;
+ crc ^= data;
+
+ return crc32c_tables[0][crc & 0xff] ^ (crc >> 8);
+}
+
+static inline uint32_t
+crc32c_2bytes(uint16_t data, uint32_t init_val)
+{
+ uint32_t crc;
+ crc = init_val;
+ crc ^= data;
+
+ crc = CRC32_UPD(crc, 1) ^ (crc >> 16);
+
+ return crc;
+}
+
+static inline uint32_t
crc32c_1word(uint32_t data, uint32_t init_val)
{
uint32_t crc, term1, term2;
@@ -367,6 +389,26 @@ crc32c_2words(uint64_t data, uint32_t init_val)
#if defined(RTE_ARCH_I686) || defined(RTE_ARCH_X86_64)
static inline uint32_t
+crc32c_sse42_u8(uint8_t data, uint32_t init_val)
+{
+ __asm__ volatile(
+ "crc32b %[data], %[init_val];"
+ : [init_val] "+r" (init_val)
+ : [data] "rm" (data));
+ return init_val;
+}
+
+static inline uint32_t
+crc32c_sse42_u16(uint16_t data, uint32_t init_val)
+{
+ __asm__ volatile(
+ "crc32w %[data], %[init_val];"
+ : [init_val] "+r" (init_val)
+ : [data] "rm" (data));
+ return init_val;
+}
+
+static inline uint32_t
crc32c_sse42_u32(uint32_t data, uint32_t init_val)
{
__asm__ volatile(
@@ -453,6 +495,52 @@ rte_hash_crc_init_alg(void)
}
/**
+ * Use single crc32 instruction to perform a hash on a byte value.
+ * Fall back to software crc32 implementation in case SSE4.2 is
+ * not supported
+ *
+ * @param data
+ * Data to perform hash on.
+ * @param init_val
+ * Value to initialise hash generator.
+ * @return
+ * 32bit calculated hash value.
+ */
+static inline uint32_t
+rte_hash_crc_1byte(uint8_t data, uint32_t init_val)
+{
+#if defined RTE_ARCH_I686 || defined RTE_ARCH_X86_64
+ if (likely(crc32_alg & CRC32_SSE42))
+ return crc32c_sse42_u8(data, init_val);
+#endif
+
+ return crc32c_1byte(data, init_val);
+}
+
+/**
+ * Use single crc32 instruction to perform a hash on a 2 bytes value.
+ * Fall back to software crc32 implementation in case SSE4.2 is
+ * not supported
+ *
+ * @param data
+ * Data to perform hash on.
+ * @param init_val
+ * Value to initialise hash generator.
+ * @return
+ * 32bit calculated hash value.
+ */
+static inline uint32_t
+rte_hash_crc_2byte(uint16_t data, uint32_t init_val)
+{
+#if defined RTE_ARCH_I686 || defined RTE_ARCH_X86_64
+ if (likely(crc32_alg & CRC32_SSE42))
+ return crc32c_sse42_u16(data, init_val);
+#endif
+
+ return crc32c_2bytes(data, init_val);
+}
+
+/**
* Use single crc32 instruction to perform a hash on a 4 byte value.
* Fall back to software crc32 implementation in case SSE4.2 is
* not supported
@@ -521,7 +609,6 @@ static inline uint32_t
rte_hash_crc(const void *data, uint32_t data_len, uint32_t init_val)
{
unsigned i;
- uint64_t temp = 0;
uintptr_t pd = (uintptr_t) data;
for (i = 0; i < data_len / 8; i++) {
@@ -529,35 +616,19 @@ rte_hash_crc(const void *data, uint32_t data_len, uint32_t init_val)
pd += 8;
}
- switch (7 - (data_len & 0x07)) {
- case 0:
- temp |= (uint64_t) *((const uint8_t *)pd + 6) << 48;
- /* Fallthrough */
- case 1:
- temp |= (uint64_t) *((const uint8_t *)pd + 5) << 40;
- /* Fallthrough */
- case 2:
- temp |= (uint64_t) *((const uint8_t *)pd + 4) << 32;
- temp |= *(const uint32_t *)pd;
- init_val = rte_hash_crc_8byte(temp, init_val);
- break;
- case 3:
+ if (data_len & 0x4) {
init_val = rte_hash_crc_4byte(*(const uint32_t *)pd, init_val);
- break;
- case 4:
- temp |= *((const uint8_t *)pd + 2) << 16;
- /* Fallthrough */
- case 5:
- temp |= *((const uint8_t *)pd + 1) << 8;
- /* Fallthrough */
- case 6:
- temp |= *(const uint8_t *)pd;
- init_val = rte_hash_crc_4byte(temp, init_val);
- /* Fallthrough */
- default:
- break;
+ pd += 4;
+ }
+
+ if (data_len & 0x2) {
+ init_val = rte_hash_crc_2byte(*(const uint16_t *)pd, init_val);
+ pd += 2;
}
+ if (data_len & 0x1)
+ init_val = rte_hash_crc_1byte(*(const uint8_t *)pd, init_val);
+
return init_val;
}
--
2.1.4
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