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Move string hashing from mbtiles to text

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Erica Fischer
2024-02-01 15:43:16 -08:00
parent 9af42515ec
commit 910aff8fe7
4 changed files with 30 additions and 15 deletions
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text.cpp
+28
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@@ -184,3 +184,31 @@ char *dtoa_milo(double val) {
}
return dup;
}
unsigned long long fnv1a(std::string const &s) {
// Store tiles by a hash of their contents (fnv1a 64-bit)
// http://www.isthe.com/chongo/tech/comp/fnv/
const unsigned long long fnv_offset_basis = 14695981039346656037u;
const unsigned long long fnv_prime = 1099511628211u;
unsigned long long h = fnv_offset_basis;
for (size_t i = 0; i < s.size(); i++) {
h ^= (unsigned char) s[i];
h *= fnv_prime;
}
return h;
}
unsigned long long fnv1a(const char *s, char additional) {
// Store tiles by a hash of their contents (fnv1a 64-bit)
// http://www.isthe.com/chongo/tech/comp/fnv/
const unsigned long long fnv_offset_basis = 14695981039346656037u;
const unsigned long long fnv_prime = 1099511628211u;
unsigned long long h = fnv_offset_basis;
for (size_t i = 0; s[i] != '\0'; i++) {
h ^= (unsigned char) s[i];
h *= fnv_prime;
}
h ^= (unsigned char) additional;
h *= fnv_prime;
return h;
}