hash: Make basis of hash_words64() 32 bits.

The basis of hash_words64() was 64 bits, even when the hash value is
32 bits, thus confusing the domain and the range of the function.
This patch fixes this by making the basis an uint32_t.

Suggested-by: Ben Pfaff <blp@nicira.com>
Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>

diff --git a/lib/hash.c b/lib/hash.c
index 1042c97..aa898a3 100644 (file)
--- a/lib/hash.c
+++ b/lib/hash.c
@@ -67,7 +67,7 @@ hash_words__(const uint32_t p[], size_t n_words, uint32_t basis)
 }
 
 uint32_t
-hash_words64__(const uint64_t p[], size_t n_words, uint64_t basis)
+hash_words64__(const uint64_t p[], size_t n_words, uint32_t basis)
 {
     return hash_words64_inline(p, n_words, basis);
 }

diff --git a/lib/hash.h b/lib/hash.h
index c2820dd..fe8d5a2 100644 (file)
--- a/lib/hash.h
+++ b/lib/hash.h
@@ -116,10 +116,9 @@ hash_words_inline(const uint32_t p[], size_t n_words, uint32_t basis)
 }
 
 static inline uint32_t
-hash_words64_inline(const uint64_t p[], size_t n_words, uint64_t basis)
+hash_words64_inline(const uint64_t p[], size_t n_words, uint32_t basis)
 {
-    return hash_words_inline((uint32_t *)p, n_words * 2,
-                             (uint32_t)basis ^ basis >> 32);
+    return hash_words_inline((uint32_t *)p, n_words * 2, basis);
 }
 
 static inline uint32_t hash_pointer(const void *p, uint32_t basis)
@@ -215,10 +214,10 @@ hash_words_inline(const uint32_t p_[], size_t n_words, uint32_t basis)
 /* A simpler version for 64-bit data.
  * 'n_words' is the count of 64-bit words, basis is 64 bits. */
 static inline uint32_t
-hash_words64_inline(const uint64_t p[], size_t n_words, uint64_t basis)
+hash_words64_inline(const uint64_t p[], size_t n_words, uint32_t basis)
 {
-    uint64_t hash1 = (uint32_t)basis;
-    uint64_t hash2 = basis >> 32;
+    uint64_t hash1 = basis;
+    uint64_t hash2 = 0;
     uint64_t hash3 = n_words;
     const uint64_t *endp = p + n_words;
     const uint64_t *limit = endp - 3;
@@ -265,7 +264,7 @@ static inline uint32_t hash_pointer(const void *p, uint32_t basis)
 #endif
 
 uint32_t hash_words__(const uint32_t p[], size_t n_words, uint32_t basis);
-uint32_t hash_words64__(const uint64_t p[], size_t n_words, uint64_t basis);
+uint32_t hash_words64__(const uint64_t p[], size_t n_words, uint32_t basis);
 
 /* Inline the larger hash functions only when 'n_words' is known to be
  * compile-time constant. */
@@ -281,7 +280,7 @@ hash_words(const uint32_t p[], size_t n_words, uint32_t basis)
 }
 
 static inline uint32_t
-hash_words64(const uint64_t p[], size_t n_words, uint64_t basis)
+hash_words64(const uint64_t p[], size_t n_words, uint32_t basis)
 {
     if (__builtin_constant_p(n_words)) {
         return hash_words64_inline(p, n_words, basis);
@@ -299,7 +298,7 @@ hash_words(const uint32_t p[], size_t n_words, uint32_t basis)
 }
 
 static inline uint32_t
-hash_words64(const uint64_t p[], size_t n_words, uint64_t basis)
+hash_words64(const uint64_t p[], size_t n_words, uint32_t basis)
 {
     return hash_words64__(p, n_words, basis);
 }