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hash_sparse: change length checks

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dont early return on 0 len, let it be the falltrough case, this seems to help branch prediction
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Alug 2026-02-22 14:03:50 +01:00 committed by NepDisk
parent 76a08efd78
commit b0da7ac519
1 changed files with 3 additions and 2 deletions
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5
src/blua/lstring.c
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@ -90,7 +90,6 @@ static unsigned hash_sparse(const char *str, size_t len)
{
/* Constants taken from lookup3 hash by Bob Jenkins. */
unsigned int a, b, h = cast(unsigned int, len);
if (len == 0) return 0;
#define rol(x, n) (((x)<<(n)) | ((x)>>(-cast(int, n)&(8*sizeof(x)-1))))
if (len >= 4) { /* Caveat: unaligned access! */
a = getu32(str);
@ -98,11 +97,13 @@ static unsigned hash_sparse(const char *str, size_t len)
b = getu32(str+(len>>1)-2);
h ^= b; h -= rol(b, 14);
b += getu32(str+(len>>2)-1);
} else {
} else if (len > 0) {
a = getu8(str);
h ^= getu8(str+len-1);
b = getu8(str+(len>>1));
h ^= b; h -= rol(b, 14);
} else {
return 0;
}
a ^= h; a -= rol(h, 11);
b ^= a; b -= rol(a, 25);