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From: Pablo de Lara <pablo.de.lara.guarch@intel.com>
To: dev@dpdk.org
Date: Tue, 12 May 2015 12:02:37 +0100
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<1431428560-25426-1-git-send-email-pablo.de.lara.guarch@intel.com>
Subject: [dpdk-dev] [PATCH v4 5/6] hash: remove duplicated code
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rte_jhash is basically like _rte_jhash_2hashes but it returns only 1 hash, instead of 2.
In order to remove duplicated code, rte_jhash calls _rte_jhash_2hashes,
passing 0 as the second seed and returning just the first hash value.
(performance penalty is negligible)
The same is done with rte_jhash2. Also, rte_jhash2 is just an specific case
where keys are multiple of 32 bits, and where no key alignment check is required.
So,to avoid duplicated code, the function calls _rte_jhash_2hashes with check_align = 0
(to use the optimal path)
Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
---
lib/librte_hash/rte_jhash.h | 293 +++++++++----------------------------------
1 files changed, 60 insertions(+), 233 deletions(-)
diff --git a/lib/librte_hash/rte_jhash.h b/lib/librte_hash/rte_jhash.h
index f1c0a8a..aa5bb2d 100644
--- a/lib/librte_hash/rte_jhash.h
+++ b/lib/librte_hash/rte_jhash.h
@@ -102,29 +102,19 @@ extern "C" {
#define LOWER16b_MASK rte_le_to_cpu_32(0xffff)
#define LOWER24b_MASK rte_le_to_cpu_32(0xffffff)
-/**
- * The most generic version, hashes an arbitrary sequence
- * of bytes. No alignment or length assumptions are made about
- * the input key.
- *
- * @param key
- * Key to calculate hash of.
- * @param length
- * Length of key in bytes.
- * @param initval
- * Initialising value of hash.
- * @return
- * Calculated hash value.
- */
-static inline uint32_t
-rte_jhash(const void *key, uint32_t length, uint32_t initval)
+static inline void
+__rte_jhash_2hashes(const void *key, uint32_t length, uint32_t *pc, uint32_t *pb, unsigned check_align)
{
uint32_t a, b, c;
/* Set up the internal state */
- a = b = c = RTE_JHASH_GOLDEN_RATIO + ((uint32_t)length) + initval;
+ a = b = c = RTE_JHASH_GOLDEN_RATIO + ((uint32_t)length) + *pc;
+ c += *pb;
- /* Check key alignment. For x86 architecture, first case is always optimal */
+ /*
+ * Check key alignment. For x86 architecture, first case is always optimal
+ * If check_align is not set, first case will be used
+ */
#if defined(RTE_ARCH_X86_64) || defined(RTE_ARCH_I686) || defined(RTE_ARCH_X86_X32)
const uint32_t *k = key;
const uint32_t s = 0;
@@ -132,8 +122,7 @@ rte_jhash(const void *key, uint32_t length, uint32_t initval)
const uint32_t *k = (uint32_t *)(uintptr_t)key & (uintptr_t)~3);
const uint32_t s = ((uintptr_t)key & 3) * CHAR_BIT;
#endif
-
- if (s == 0) {
+ if (!check_align || s == 0) {
while (length > 12) {
a += k[0];
b += k[1];
@@ -172,7 +161,9 @@ rte_jhash(const void *key, uint32_t length, uint32_t initval)
a += k[0] & LOWER8b_MASK; break;
/* zero length strings require no mixing */
case 0:
- return c;
+ *pc = c;
+ *pb = b;
+ return;
};
} else {
/* all but the last block: affect some 32 bits of (a, b, c) */
@@ -238,63 +229,16 @@ rte_jhash(const void *key, uint32_t length, uint32_t initval)
break;
/* zero length strings require no mixing */
case 0:
- return c;
+ *pc = c;
+ *pb = b;
+ return;
}
}
__rte_jhash_final(a, b, c);
- return c;
-}
-
-/**
- * A special optimized version that handles 1 or more of uint32_ts.
- * The length parameter here is the number of uint32_ts in the key.
- *
- * @param k
- * Key to calculate hash of.
- * @param length
- * Length of key in units of 4 bytes.
- * @param initval
- * Initialising value of hash.
- * @return
- * Calculated hash value.
- */
-static inline uint32_t
-rte_jhash2(const uint32_t *k, uint32_t length, uint32_t initval)
-{
- uint32_t a, b, c;
-
- /* Set up the internal state */
- a = b = c = RTE_JHASH_GOLDEN_RATIO + (((uint32_t)length) << 2) + initval;
-
- /* Handle most of the key */
- while (length > 3) {
- a += k[0];
- b += k[1];
- c += k[2];
-
- __rte_jhash_mix(a, b, c);
-
- k += 3;
- length -= 3;
- }
-
- /* Handle the last 3 uint32_t's */
- switch (length) {
- case 3:
- c += k[2];
- case 2:
- b += k[1];
- case 1:
- a += k[0];
- __rte_jhash_final(a, b, c);
- /* case 0: nothing left to add */
- case 0:
- break;
- };
-
- return c;
+ *pc = c;
+ *pb = b;
}
/**
@@ -315,138 +259,7 @@ rte_jhash2(const uint32_t *k, uint32_t length, uint32_t initval)
static inline void
rte_jhash_2hashes(const void *key, uint32_t length, uint32_t *pc, uint32_t *pb)
{
- uint32_t a, b, c;
-
- /* Set up the internal state */
- a = b = c = RTE_JHASH_GOLDEN_RATIO + ((uint32_t)length) + *pc;
- c += *pb;
-
- /* Check key alignment. For x86 architecture, first case is always optimal */
-#if defined(RTE_ARCH_X86_64) || defined(RTE_ARCH_I686) || defined(RTE_ARCH_X86_X32)
- const uint32_t *k = key;
- const uint32_t s = 0;
-#else
- const uint32_t *k = (uint32_t *)(uintptr_t)key & (uintptr_t)~3);
- const uint32_t s = ((uintptr_t)key & 3) * CHAR_BIT;
-#endif
-
- if (s == 0) {
- while (length > 12) {
- a += k[0];
- b += k[1];
- c += k[2];
-
- __rte_jhash_mix(a, b, c);
-
- k += 3;
- length -= 12;
- }
-
- switch (length) {
- case 12:
- c += k[2]; b += k[1]; a += k[0]; break;
- case 11:
- c += k[2] & LOWER24b_MASK; b += k[1]; a += k[0]; break;
- case 10:
- c += k[2] & LOWER16b_MASK; b += k[1]; a += k[0]; break;
- case 9:
- c += k[2] & LOWER8b_MASK; b += k[1]; a += k[0]; break;
- case 8:
- b += k[1]; a += k[0]; break;
- case 7:
- b += k[1] & LOWER24b_MASK; a += k[0]; break;
- case 6:
- b += k[1] & LOWER16b_MASK; a += k[0]; break;
- case 5:
- b += k[1] & LOWER8b_MASK; a += k[0]; break;
- case 4:
- a += k[0]; break;
- case 3:
- a += k[0] & LOWER24b_MASK; break;
- case 2:
- a += k[0] & LOWER16b_MASK; break;
- case 1:
- a += k[0] & LOWER8b_MASK; break;
- /* zero length strings require no mixing */
- case 0:
- *pc = c;
- *pb = b;
- return;
- };
- } else {
- /* all but the last block: affect some 32 bits of (a, b, c) */
- while (length > 12) {
- a += BIT_SHIFT(k[0], k[1], s);
- b += BIT_SHIFT(k[1], k[2], s);
- c += BIT_SHIFT(k[2], k[3], s);
- __rte_jhash_mix(a, b, c);
-
- k += 3;
- length -= 12;
- }
-
- /* last block: affect all 32 bits of (c) */
- switch (length) {
- case 12:
- a += BIT_SHIFT(k[0], k[1], s);
- b += BIT_SHIFT(k[1], k[2], s);
- c += BIT_SHIFT(k[2], k[3], s);
- break;
- case 11:
- a += BIT_SHIFT(k[0], k[1], s);
- b += BIT_SHIFT(k[1], k[2], s);
- c += BIT_SHIFT(k[2], k[3], s) & LOWER24b_MASK;
- break;
- case 10:
- a += BIT_SHIFT(k[0], k[1], s);
- b += BIT_SHIFT(k[1], k[2], s);
- c += BIT_SHIFT(k[2], k[3], s) & LOWER16b_MASK;
- break;
- case 9:
- a += BIT_SHIFT(k[0], k[1], s);
- b += BIT_SHIFT(k[1], k[2], s);
- c += BIT_SHIFT(k[2], k[3], s) & LOWER8b_MASK;
- break;
- case 8:
- a += BIT_SHIFT(k[0], k[1], s);
- b += BIT_SHIFT(k[1], k[2], s);
- break;
- case 7:
- a += BIT_SHIFT(k[0], k[1], s);
- b += BIT_SHIFT(k[1], k[2], s) & LOWER24b_MASK;
- break;
- case 6:
- a += BIT_SHIFT(k[0], k[1], s);
- b += BIT_SHIFT(k[1], k[2], s) & LOWER16b_MASK;
- break;
- case 5:
- a += BIT_SHIFT(k[0], k[1], s);
- b += BIT_SHIFT(k[1], k[2], s) & LOWER8b_MASK;
- break;
- case 4:
- a += BIT_SHIFT(k[0], k[1], s);
- break;
- case 3:
- a += BIT_SHIFT(k[0], k[1], s) & LOWER24b_MASK;
- break;
- case 2:
- a += BIT_SHIFT(k[0], k[1], s) & LOWER16b_MASK;
- break;
- case 1:
- a += BIT_SHIFT(k[0], k[1], s) & LOWER8b_MASK;
- break;
- /* zero length strings require no mixing */
- case 0:
- *pc = c;
- *pb = b;
- return;
- }
- }
-
- __rte_jhash_final(a, b, c);
-
- *pc = c;
- *pb = b;
+ __rte_jhash_2hashes(key, length, pc, pb, 1);
}
/**
@@ -467,40 +280,54 @@ rte_jhash_2hashes(const void *key, uint32_t length, uint32_t *pc, uint32_t *pb)
static inline void
rte_jhash2_2hashes(const uint32_t *k, uint32_t length, uint32_t *pc, uint32_t *pb)
{
- uint32_t a, b, c;
+ __rte_jhash_2hashes((const void *) k, (length << 2), pc, pb, 0);
+}
- /* Set up the internal state */
- a = b = c = RTE_JHASH_GOLDEN_RATIO + (((uint32_t)length) << 2) + *pc;
- c += *pb;
+/**
+ * The most generic version, hashes an arbitrary sequence
+ * of bytes. No alignment or length assumptions are made about
+ * the input key.
+ *
+ * @param key
+ * Key to calculate hash of.
+ * @param length
+ * Length of key in bytes.
+ * @param initval
+ * Initialising value of hash.
+ * @return
+ * Calculated hash value.
+ */
+static inline uint32_t
+rte_jhash(const void *key, uint32_t length, uint32_t initval)
+{
+ uint32_t initval2 = 0;
- /* Handle most of the key */
- while (length > 3) {
- a += k[0];
- b += k[1];
- c += k[2];
+ rte_jhash_2hashes(key, length, &initval, &initval2);
- __rte_jhash_mix(a, b, c);
+ return initval;
+}
- k += 3;
- length -= 3;
- }
+/**
+ * A special optimized version that handles 1 or more of uint32_ts.
+ * The length parameter here is the number of uint32_ts in the key.
+ *
+ * @param k
+ * Key to calculate hash of.
+ * @param length
+ * Length of key in units of 4 bytes.
+ * @param initval
+ * Initialising value of hash.
+ * @return
+ * Calculated hash value.
+ */
+static inline uint32_t
+rte_jhash2(const uint32_t *k, uint32_t length, uint32_t initval)
+{
+ uint32_t initval2 = 0;
- /* Handle the last 3 uint32_t's */
- switch (length) {
- case 3:
- c += k[2];
- case 2:
- b += k[1];
- case 1:
- a += k[0];
- __rte_jhash_final(a, b, c);
- /* case 0: nothing left to add */
- case 0:
- break;
- };
+ rte_jhash2_2hashes(k, length, &initval, &initval2);
- *pc = c;
- *pb = b;
+ return initval;
}
static inline uint32_t
--
1.7.4.1