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Use Knuth multiplicative hashing for the symbol table.

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FossilOrigin-Name: cc29ddd6be60bdbf107f285c9eb57d5896ebca2d
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drh
2016-09-28 20:42:31 +00:00
parent 5e769a50ad
commit 5f33eaa6a4
3 changed files with 12 additions and 8 deletions
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6
src/hash.c
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@@ -56,7 +56,11 @@ static unsigned int strHash(const char *z){
unsigned int h = 0;
unsigned char c;
while( (c = (unsigned char)*z++)!=0 ){ /*OPTIMIZATION-IF-TRUE*/
h = (h<<3) ^ h ^ sqlite3UpperToLower[c];
/* Knuth multiplicative hashing. (Sorting & Searching, p. 510).
** 0x9e3779b1 is 2654435761 which is the closest prime number to
** (2**32)*golden_ratio, where golden_ratio = (sqrt(5) - 1)/2. */
h += sqlite3UpperToLower[c];
h *= 0x9e3779b1;
}
return h;
}