To the best of my knowledge, the Perl hash algorithm is:

unsigned int hash = 0;
while (*s)  /* s is pointer to string */
    hash = hash * 33 + *s++;
return hash;
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Except that it isn't anymore. The above was the case for 5.6.*, but it has changed in 5.8.0, and then again in 5.8.1. Since 5.8, it is doing the shifts you seem to dislike. From hv.h:

/* hash a key */
/* FYI: This is the "One-at-a-Time" algorithm by Bob Jenkins
 * from requirements by Colin Plumb.
 * (http://burtleburtle.net/bob/hash/doobs.html) */
/* The use of a temporary pointer and the casting games
 * is needed to serve the dual purposes of
 * (a) the hashed data being interpreted as "unsigned char" (new since
+ 5.8,
 *     a "char" can be either signed or unsigned, depending on the com
+piler)
 * (b) catering for old code that uses a "char"
 * 
 * The "hash seed" feature was added in Perl 5.8.1 to perturb the resu
+lts
 * to avoid "algorithmic complexity attacks".
 * 
 * If USE_HASH_SEED is defined, hash randomisation is done by default
 * If USE_HASH_SEED_EXPLICIT is defined, hash randomisation is done
 * only if the environment variable PERL_HASH_SEED is set.
 * For maximal control, one can define PERL_HASH_SEED.
 * (see also perl.c:perl_parse()).
 */
#ifndef PERL_HASH_SEED
#   if defined(USE_HASH_SEED) || defined(USE_HASH_SEED_EXPLICIT)
#       define PERL_HASH_SEED   PL_hash_seed
#   else
#       define PERL_HASH_SEED   0
#   endif
#endif

#define PERL_HASH(hash,str,len) PERL_HASH_INTERNAL_(hash,str,len,0)

/* Only hv.c and mod_perl should be doing this.  */
#ifdef PERL_HASH_INTERNAL_ACCESS
#define PERL_HASH_INTERNAL(hash,str,len) PERL_HASH_INTERNAL_(hash,str,
+len,1)
#endif

/* Common base for PERL_HASH and PERL_HASH_INTERNAL that parameterises
 * the source of the seed. Not for direct use outside of hv.c. */

#define PERL_HASH_INTERNAL_(hash,str,len,internal) \
     STMT_START { \
        register const char * const s_PeRlHaSh_tmp = str; \
        register const unsigned char *s_PeRlHaSh = (const unsigned cha
+r *)s_PeRl
HaSh_tmp; \
        register I32 i_PeRlHaSh = len; \
        register U32 hash_PeRlHaSh = (internal ? PL_rehash_seed : PERL
+_HASH_SEED
); \
        while (i_PeRlHaSh--) { \
            hash_PeRlHaSh += *s_PeRlHaSh++; \
            hash_PeRlHaSh += (hash_PeRlHaSh << 10); \
            hash_PeRlHaSh ^= (hash_PeRlHaSh >> 6); \  
        } \
        hash_PeRlHaSh += (hash_PeRlHaSh << 3); \
        hash_PeRlHaSh ^= (hash_PeRlHaSh >> 11); \
        (hash) = (hash_PeRlHaSh + (hash_PeRlHaSh << 15)); \
    } STMT_END
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